EPA-600/2-77-240
December 1977 Environmental Protection Technology Series
AN INTRODUCTION TO THE TECHNOLOGY OF
SUBSURFACE WASTEWATER INJECTION
f< Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
EPA/600/2-77/240 U.S. Environmental Protection Agency
Ada, Oklahoma 74820
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EPA-600/2-77-240
December 1977
AN INTRODUCTION TO THE TECHNOLOGY OF
SUBSURFACE WASTEWATER INJECTION
by
Don L. Warner
University of Missouri--Rol 1 a
Roll a, Missouri 65401
and
Jay H. Lehr
National Water Well Association
Worthing ton, Ohio 43085
Grant No. R-803889
Project Officer
Jack U. Keeley
Ground Water Research Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental
Research Laboratory, U.S. Environmental Protection Agency, and approved
for publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection Agency,
nor does mention of trade names or commercial products constitute endorsement
or recommendation for use.
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FOREWORD
The Environmental Protection Agency was established to coordinate
administration of the major Federal programs designed to protect the
quality of our environment.
An important part of the Agency's effort involves the search for
information about environmental problems, management techniques, and new
technologies through which optimum use of the Nation's land and water
resources can be assured and the threat pollution poses to the welfare
of the American people can be minimized.
EPA's Office of Research and Development conducts this search through
a nationwide network of research facilities.
As one of these facilities, the Robert S. Kerr Environmental Research
Laboratory is responsible for the management of programs to: (a) investi-
gate the nature, transport, fate, and management of pollutants in ground
water; (b) develop and demonstrate methods for treating wastewaters with
soil and other natural systems; (c) develop and demonstrate pollution con-
trol technologies for irrigation return flows; (d) develop and demonstrate
pollution control technologies for animal production wastes; (e) develop
and demonstrate technologies to prevent, control or abate pollution from
the petroleum refining and petrochemical industries; and (f) develop and
demonstrate technologies to manage pollution resulting from combinations
of industrial wastewaters or industrial/municipal wastewaters.
This report contributes to that knowledge which is essential in order
for EPA to establish and enforce pollution control standards which are
reasonable, cost effective, and provide adequate environmental protection
for the American public.
.•Ji 1 1 i am C . Ga 1 eqar
Di rector
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PREFACE
An Introduction to the Technology of Subsurface Wastewater Injection
has been developed by the National Water Well Association, in conjunction
with the U.S. Environmental Protection Agency for use by all those involved
in the planning, design, construction, operation and abandonment of injection
wells. It is hoped that this text will serve as both a guide to and a stand-
ard for injection well construction and maintenance.
For those concerned with the regulatory aspects of subsurface wastewater
injection, it will provide the minimum criteria necessary to protect under-
ground water from degradation. Industries may use this manual to evaluate
injection as an alternate to other means of waste disposal and it will serve
as a constant reference source for those who design, construct, and operate
these systems. Finally, this manual fulfills that mandate contained in the
Safe Drinking Water Act (P.L. 93-523) requiring that the Administrator of the
Environmental Protection Agency "... carry out a study of methods of under-
ground injection which do not result in the degradation of underground drink-
ing water sources."
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ABSTRACT
When wastewater is injected into deep wells for disposal, it can pose
a serious environmental threat unless the injection process is carefully
planned and executed from start to finish.
Local geologic and hydrologic conditions must be thoroughly investigated
including such characteristics as structure, stratigraphy, composition and
engineering properties of the underlying formations. The nature of injection
and confining intervals will determine the conditions that the injection
wells must meet, or whether such wells are even feasible. Specific informa-
tion acquired through the use of cores, probes, and other tests, will help to
pinpoint areas of potential difficulty, and should suggest ways to avoid these
problems.
Once an injection site has been selected, the injection interval must
be tested to insure that it is physically, biologically, and chemically com-
patible with the wastewater to be injected. Both the injection interval and
the wastewater must be examined to guarantee that each will remain stable over
an extended period of time. If problems exist, the wastewater can be treated
to make it more compatible with the injection interval. Failure to bring the
wastewater and injection interval into compatibility can lead to excessive
corrosion, clogging, well and plant damage, and may necessitate well abandon-
ment.
The injection well itself must be carefully designed and constructed to
guarantee the safety and integrity of the injected wastewater as well as of
the surrounding formations, and natural resources. When construction of the
injection well is completed, the well should undergo final testing to estab-
lish records of baseline conditions for future reference and comparison. At
this time, operating procedures and emergency precautions should be established
and approval should be obtained from the necessary regulatory agencies. Only
then can full-scale wastewater injection begin.
An operating injection well should be monitored throughout its working
life for any changes in injection conditions that may lead to system failure.
An injection well operator has the responsibility of knowing what and where
the injected wastewater is and for keeping adequate operating records. When
an injection well system permanently ceases operating, the well must be pro-
perly sealed and a record, describing the method and date of sealing and the
precise location of the well should be filed with the proper authorities.
When the guidelines for injection well operation set forth here are followed
the safety and success of this method of wastewater disposal will be insured.
;?)is report, was suhri t ted in f uUi 1 Kent of '.rant 'In. R-8038B9 hv the
'.ational ,,'ater '..'oil Association .mder the sponsor'sh i;.; of the Robert S. Kt-rr
: iivi ror.i'it'i'ta 1 Research Labora turv, Ada, Okl rihora , ,'ir.d trie Municipal :nviron-
•'er.tal i;i:",t'a rch 1. dbor,: tor/, r i r.r; i r>na t i , Ohio, \:.'~'. I r. vi ronr.enta ! Protection
A,:,CM. y. ~hi'> report covers Li ;HM"ind ' ro1':; July •: ; , ': '•'" to • ?'..;];• /',', I:*//,
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CONTENTS
Foreword iii
Preface iv
Abstract v
List of Abbreviations viii
Acknowledgments ix
1. Introduction 1
Objectives and Scope 1
Historical Review of Injection Well Use 2
Dimensions and Units of Measurement 8
References 14
Appendix 16
2. The Geologic and Hydrologic Environment 21
Injection and Confining Intervals 21
Rock Types 22
Stratigraphic Geology 22
Structural Geology 30
Engineering Properties of Rocks 36
References 61
3. Acquisition and Use of Geologic and Hydrologic Data
for Injection Well Site Evaluation 64
Data Obtainable fron Existing Sources
Prior to Drilling 64
Data Obtainable During i'.'ell Construction and Testing. . 6:;
References 120
4. Criteria for Injection Well Site Evaluation 124
Regional Lvaluation
Local Site [valuation 140
Re f(> rerres 1 'j4
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5. Wastewater Characteristics 157
Volume 157
Physical Characteristics 159
Chemical Characteristics 162
Biological Characteristics 176
Wastewater Sampling and Analysis 178
Wastewater Classification 178
References ' 182
6. Pre-Injection Wastewater Treatment and
Surface Facility Design 188
Plant Process Control 188
Treatment Processes 190
Injection Pumps 218
Examples of Integrated Treatment Facility Design . . . 220
References 230
7. Injection Well Design and Construction 234
Planning a Well 234
Tubing and Casing Design 243
Packer Selection 250
Drilling the Well 251
Cementing 265
Casing Landing 271
Well Stimulation 275
Completion Reports 276
Design Examples 277
References 278
8. Pre-Injection Preparation and Start-Up Operations 283
Pre-Injection Testing 283
Operating Program , 285
Problems Encountered During Start-Up 286
State Requirements for Approval of Operations 288
References 292
9. Injection Well Monitoring 293
Periodic Inspection and Testing 299
Monitoring Wells 310
Other Monitoring Methods 314
References 317
10. Injection Well Abandonment 320
References 328
Glossary 329
vn
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LIST OF ABBREVIATIONS
C -- Centigrade
cm -- Centimeter
cp -- Centipoise
cu -- Cubic
Ctgs -- Cuttings
F -- Fahrenheit
ft -- Foot
gal -- Gallons
gpm -- Gallons per Minute
g or gr -- Grams
in --Inch
ipy -- Inches per Year
kg -- Kilogram
m -- Meter
mg -- Milligrams
mg/1 -- Milligrams per Liter
mdd -- Milligrams per Square Decimeter per Day
mgd -- Million Gallons per Day
mpy -- Mills per Year
min -- Minutes
OD -- Outside Diameter
ppm -- Parts per Million
Ib -- Pound
psi -- Pounds per Square Inch
psig -- Pounds per Square Inch Gaqe
SpGr -- Specific Gravity
sq -- Square
TDS -- Total Dissolved Solids
T -- Transmissivity
yr -- Year
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ACKNOWLEDGMENTS
It is important that the views of the State and Federal government and
industry be reflected in this document. It is imperative that it stand the
critical review of those whose profession is in some way associated with sub-
surface wastewater injection. To that end an advisory review panel was select-
ed to guide the development of this manual from its conception through the
final manuscript. The panel was composed of the following men:
Mr. Robert R. Balmer
E.I. DuPont DeNemours & Co.
Mr. Robert E. Bergstrom
Illinois State Geological
Survey
Mr. Jerry Calvert
Dowel 1 Division
The Dow Chemical Company
Mr. Jack Garrett
Monsanto Company
Mr. Allan Kerr
Department of the Environment
CANADA
Mr. Phillip E. Lamoureaux
Geological Survey of Alabama
Mr. L. E. Mann ion
Stauffer Chemical Company
Mr. Jerry W. Mullican
Texas Water Quality Board
Mr. Dwight Smith
Hal 1iburton Services
Mr. Jack S. Talbot
The Dow Chemical Company
Mr. Leonard A. Wood
U.S. Geological Survey
These individuals, all expert in some facet of this text's subject
matter made a continuing and comprehensive effort to insure that a significant
and practical contribution was hereby made to the literature of subsurface
emplacement of liquid waste.
Worthy of special mention is the contribution made by Mr. Michael
D. Campbell, Consulting Geologist of Houston, Texas, who served as a consul-
tant to the authors throughout the project. His tangible contribution is most
apparent in the writing of Chapters 6 (Pre-Injection Wastewater Treatment and
Surface Facility Design), 7 (Injection Well Design and Construction), 8 (Pre-
Injection Preparation and Start-Up Operations), and 10 (Injection Well Aban-
donment) .
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CHAPTER 1
INTRODUCTION
OBJECTIVES AND SCOPE
An Introduction to the Technology of Subsurface Wastewater Injection
has been prepared to assist engineers, geologists, and others in the tasks of
planning, designing, constructing, operating, and regulating industrial and
municipal wastewater injection well systems. It is apparent to anyone review-
ing the literature that a great deal has been written about this subject in
the past twenty-five and particularly the past ten years. Also, there is an
extensive literature in the related fields of petroleum engineering and
ground water hydrology that can be applied to injection well technology. One
purpose of this publication is, therefore, to provide a summary of selected
information in a form convenient for use by well operators, engineering con-
sultants, and regulatory authorities in performing their respective tasks,
so that injection wells may be used, where desirable, more efficiently and
with a minimal potential for environmental damage.
Impetus for development of An Introduction to the Technology of Sub-
surface Wastewater Injection was provided by passage of Public Law 92-500,
the Federal Water Pollution Control Act Amendments of 1972 and Public Law
93-523, the Safe Drinking Water Act of 1974. Both of these laws contain spe-
cific provisions concerning wastewater injection wells. Public Law 92-500
requires that, in order to qualify for participation in the National Pollu-
tion Discharge Elimination System permitting program, states must have ade-
quate authority to issue permits which control the disposal of pollutants into
wells. Therefore, it is only technically necessary that a state have the
authority to issue or deny permits to qualify. However, to do this it is
necessary to have a program for permit evaluation. The Safe Drinking '.later
Act requires that EPA develop regulations for state underground injection con-
trol programs. The objective of the law is to insure that underground injec-
tion does not endanger drinking water sources. This guide is a technical
document intended to complement the required EPA regulations.
Included in the technical guide are chapters concerning the units of
measurement used in injection well engineering, the nature of the subsurface
geologic and hydrologic environment, the means of acquiring subsurface geolo-
gic and hydrologic data, the criteria used for injection well site evaluation,
the physical and chemical properties of wastewater, wastewater classification,
;'!"(•-i nic-'.t ion wastowd ter treatment, injection well design and cm,:, trut. t im;,
the procedures pn.'paratory to injection, well operation and moni tori iv.i and
system abandonment. The flow of these chapters is approximatel y in the order'
that, the ma t or i a 1 is used duriru; the plannim;, cons t rut. t i mi, opera ?.. i no , and
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abandoning an injection system. References used in the text are listed and
appendices included at the end of each individual chapter.
Until the mid-19601s, the subject of the technical guide was described
as deep-well disposal. Some still use this terminology. However, the major-
ity now seem to prefer the terminology subsurface or underground injection of
wastewater or waste liquid. In any case, what is being discussed here is the
introduction of liquid industrial and municipal wastes into the subsurface
through drilled deep-wells.
When used in this context, the word deep cannot be given any specific
value, but refers to the depth required to reach a porous, permeable, saline-
water-bearing rock stratum that is vertically confined by relatively imper-
meable beds. As will be covered later, the minimum depth of burial, the nec-
essary thickness of confining strata, and the minimum salinity of water in
the injection interval must be determined in each individual case.
Unregulated disposal of municipal and industrial wastes through shallow
wells into strata containing potable ground water has been and still is
practiced (TEMPO, 1973, p. 2-42 to 2-58), in spite of its obvious undesira-
bility. In contrast to this practice, the subject here is the controlled em-
placement of wastewater into the subsurface in such a manner that hazard to
drinking water sources and other resources is minimized. Although much of
the technology described in the engineering guide is applicable to oilfield
brine disposal, oilfield brine injection is excluded from consideration be-
cause of differences in regulation and practice that make it impractical to
treat it simultaneously with other industrial and municipal wastewater in-
jection.
HISTORICAL REVIEW OF INJECTION WELL USE
The following section provides a perspective on the historical develop-
ment and recent status of wastewater injection.
It is not certain where controlled wastewater injection was first prac-
ticed outside of the oilfield, but Harlow, in an article published in 1939
(Harlow, 1939) described problems encountered by Dow Chemical Company in
disposing of waste brines from chemical manufacturing by subsurface injection.
Inventories by various individuals and groups have succeeded in locating no
more than four such wells constructed prior to 1950. A 1963 inventory by
Donaldson (1964) listed only 30 wells. Subsequent inventories published in
1967 (Warner, 1967), 1968 (Ives and Eddy, 1968), 1972 (Warner, 1972), and
1974 (U.S. EPA, 1974) listed 110, 118, 246, and 278 wells respectively. The
most recent inventory (Reeder, et al, 1975) showed that a total of 322 indus-
trial and municipal injection wells had been drilled up to January, 1975, and
209 of those were reportedly operating at that time.
Examination of some of the characteristics of the disposal systems that
have been constructed will assist in developing a view of the nature of in-
jection well practice to date. First, it is of interest to know the geogra-
phic distribution of these wells and their operating status. This informa-
tion is shown in Table 1-1. It is apparent that a large percentage of the
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TABLE 1-1. DISTRIBUTION AND OPERATING STATUS OF INJECTION WELLS
IN THE UNITED STATES (REEDER, ET AL., 1975).
AREA TOTAL
REGION II
NEW YORK
REGION III
PENNSYLVANIA
WEST VIRGINIA
REGION IV
ALABAMA
FLORIDA
KENTUCKY
MISSISSIPPI
NORTH CAROLINA
TENNESSEE
REGION V
ILLINOIS
INDIANA
MICHIGAN
OHIO
REGION VI
ARKANSAS
LOUISIANA
NEW MEXICO
OKLAHOMA
TEXAS
REGION VII
IOWA
KANSAS
REGION VIII
COLORADO
WYOMING
REGION IX
CALIFORNIA
HAWAI I
NEVADA
TOTAL
KEY:
0 Opera tinq
NOP Not Opera tinq,
NOUP Not Opera tinq,
DN Drilled, Never
PNL) Pc-nin tted, Not
PC Perx.it Cancel 1
SNA SLU.ir1. Unknown
NO. WELLS
4
9
7
5
10
3
2
4
4
8
13
34
10
1
85
1
15
124
1
30
2
1
5
4
1
383
PI uqqed
Uripl uqqed
Used
Dri lied
ed, Never D
0 NOP NOUP
1
0 9
6
2
4 1 1
2 1
1
1
2 1
4 1
11 1
21 4 3
6 1
1
52 8
1
10 1
57 12 6
21 2
1 1
1
4 1
1
1
209 38 18
ri 1 led
DN PND PC
3
1
3
1 3
1
3
1
1 1
1
5 1
3
5 19 1
4
16 8 18
1
7
2 1
57 34 19
SNA
1
7
8
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wells constructed by January, 1975 were located in Texas (91) and Louisiana
(65). Most of the remainder were located in the industrialized north and
east central states (Regions II, III, and V - 73 wells), Kansas (30), and
Oklahoma (15), leaving only 48 wells scattered throughout the remaining
states.
The distribution by industry of the 268 wells for which information was
available in 1973 is shown in Table 1-2. The largest number of wells (131)
had been constructed by the chemical industry, which includes petrochemical
and pharmaceutical plants. Fifty-one wells had been constructed at petroleum
refineries and 17 at natural gas plants. Steel mills were another major user
of injection wells (16). Among the other industries that have constructed
wells are a photo-processing facility, an airline maintenance shop, a paper
mill, a uranium mill, a uranium processing plant, a petroleum service company,
an automobile plant, a laundromat, two food-processing plants, an acid-leach
mining operation, a coal mine, several solution mining operations, and an
electronic components plant. In Oklahoma and Texas, several wells are opera-
ted by contractors that are collecting and injecting a variety of wastes from
contracting industries. The 1973 survey listed 23 wells constructed for in-
jection of municipal wastewater, which may also include industrial wastes
discharged into sanitary sewers.
As will be discussed later in detail, nearly all types of rocks can,
under favorable circumstances, have sufficient porosity and permeability to
accept large quantities of injected wastewater. However, in practice, most
wells have been constructed to inject into sand or sandstone (62 percent) and
limestone or dolomite (33.8 percent). A very few wells have injected into
other types of rocks, including shale, salt and other evaporites, igneous and
metamorphic rocks, and various other combinations (Table 1-3). The ages of
these rocks range from Quaternary to Precambrian (Table 1-3). One hundred
and six (106) wells were completed in strata of Tertiary or Quaternary age,
93 in sand and sandstone and 13 in limestone or evaporite. Only 20 wells
were completed in Mesozoic age strata, primarily sandstone. Palozoic age
strata have received the most use (143 wells). Three groups of rocks stand
out as having received major use for injections: Quaternary and Tertiary
age sands of the Gulf Coast geologic province of Texas, Louisiana, and Ala-
bama; the Cambrian-Ordovician Arbuckle Group (carbonate) in Kansas and Okla-
homa; and the Cambrian Mt. Simon Sandstone and its equivalents in the north-
central states.
Of the injection wells that have been constructed, few are shallower
than 1,000 ft. (Table 1-4). This is principally because injection intervals
are selected so that they are sufficiently deep to provide adequate separa-
tion from potable subsurface water, which usually occurs at shallower depths.
On the other hand, few wells deeper than 6,000 ft. have been constructed be-
cause of cost and because satisfactory intervals have usually been found at
lesser depths.
Using data from the 1973 survey, Warner and Orcutt (1973) estimated
that 60 percent of the wells that had operated up to that time had injected
less than 100 gallons per minute (computed as if the wells were operated con-
tinuously 24 hours per day 365 days per year) and 95 percent were injecting
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TABLE 1-2. STANDARD INDUSTRIAL CLASSIFICATION OF 268 INJECTION WELLS -
1973 (U.S. ENVIRONMENTAL PROTECTION AGENCY, 1974).
MINING (9.3%)
10 METAL MINING
12 COAL
13 OIL & GAS EXTRACTION
14 NON-METALLIC MINING
MANUFACTURING (80.6%)
20 FOOD
26 PAPER
28 CHEMICAL & ALLIED PRODUCTS
29 PETROLEUM REFINING
32 STONE & CONCRETE
33 PRIMARY METALS
34 FABRICATED METALS
35 MACHINERY - EXCEPT ELECTRONICS
36 ELECTRONICS
38 PHOTOGRAPH ICS
TRANSPORTATION, GAS, AND SANITARY SERVICES (9.8%)
47 TRANSPORTATION SERVICE
49 SANITARY SERVICE
50 WHOLESALE TRADE - DURABLE
55 AUTO DEALERS & SERVICE
WELLS
2
1
17
5
6
3
131
51
1
16
3
1
1
3
1
23
1
1
PERCENTAGE
.7
.4
6.4
1.9
2.2
1.1
48.9
19.0
.4
5.9
1.1
.4
.4
1.1
.4
8.6
.4
.4
OTHER (.4°0
72"" PERSONAL SERVICE 1 .4
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TABLE 1-3. RESERVOIR ROCK TYPE AND AGE OF 269 WELLS
(U.S. ENVIRONMENTAL PROTECTION AGENCY, 1974).
(%}
TERTIARY & QUATERNARY 39.4
CRETACEOUS
JURASSIC ' 7.4
TRIASSIC !
PERMIAN
PENNSYLVANIAN
MISSISSIPPI
DEVONIAN = 58.2
SILURIAN
ORDOVICIAN
CAMBRIAN
pre-CAMBRIAN .4
TOTAL (269)
%
SAND &
SANDSTONE
93
19
1
12
5
4
10
1
2
20
167
62.1
CARBONATE
11
14
2
1
21
3
20
19
91
33.8
EVAPORITE
2
2
4
8
3
SHALE
1
1
2
.7
OTHER
1
1
.4
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TABLE 1-4. WELL COMPLETION DEPTHS OF 259 WELLS (MODIFIED AFTER
U.S. ENVIRONMENTAL PROTECTION AGENCY, 1974).
DEPTH
0
1001
2001
3001
4001
5001
6001
7001
8001
- 1000
- 2000
- 3000
- 4000
- 5000
- 6000
- 7000
- 8000
+
NO. WELLS
20
56
33
34
39
44
18
12
3
PERCENTAGE
7.7
21.6
12.7
13.1
15.1
17.0
6.9
4.6
1.2
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less than 400 gallons per minute. Warner and Orcutt (1973) also found that
virtually all wells had injected at less than 1,500 psi and that 78 percent
had injected at less than 600 psi.
DIMENSIONS AND UNITS OF MEASUREMENT
In many fields of engineering and science, specialized units of measure-
ment have been developed either for an express purpose or by circumstance
without a purpose.
Such units become familiar to those using them, but can be an irrita-
tion to workers from other fields who may have neither the time nor patience
to adjust to them. This has long been an obstruction to exchange of infor-
mation between workers in petroleum engineering and groundwater hydrology.
Since these are the two fields most closely allied to subsurface wastewater
injection, the literature concerning wastewater injection contains a hetero-
geneous mix of terms and units from both, as well as from such other allied
fields as civil and chemical engineering.
Upon examination, it can be ascertained that most of the troublesome
units of measurement are composed of one or more of three primary quantities,
length [L], mass [M] and time [t]. These quantities or dimensions are ex-
pressed, for example, in metric units—centimeters, grams, seconds, or
English units--feet, pounds, seconds, or multiples and subdivisions of these.
Other primary quantities (e.g. temperature -[T]) also exist, but are less
frequently encountered. It would not be too troublesome to convert from the
primary quantities in one system of units to those in another, but, unfor-
tunately, the primary quantities are used in such mixtures and so obscured
in "practical" units that it can be very difficult to work out the conver-
sions. However, if it is understood that only the three primary quantities
of length, mass, and time are involved, then the relationship between prac-
tical units in different systems can be appreciated and transfer can be con-
fidently made from one system to another, when necessary, by using conversion
factors that are given, or by working out the needed factors.
As an elementary example of the above discussion, consider the measure-
ment of flow rates. Flow rates (Q) are commonly in barrels/day in petroleum
engineering and in gallons/minute or gallons/day in groundwater. Obviously,
flow rate has the dimensions of volume/time [L^/t], but this is well hidden
in the practical units, barrels and gallons. Both barrels and gallons can
be converted to cubic meters or cubic feet, then equated, or one can go di-
rectly from barrels to gallons, if it is known that one barrel equals 42
gallons.
As a more complex example, the conversion from units of hydraulic con-
ductivity to those of intrinsic permeability will be analyzed. Darcy's law,
as it is written for units of hydraulic conductivity is:
n = AK dh
Q AKdU (1-1)
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where:
Q - flow rate [L3/t]
A = area through which flow occurs [L2]
K = hydraulic conductivity
h = hydraulic head [L]
L = length of flow path [L]
by analyzing the dimensions in Equation 1-1, the dimensions of hydraulic
conductivity are found to be:
[K] = kt. x L = L
L2 L I
Placement of the left hand side of an equation in brackets is a conven-
tional means of stating that the bracketed quantity has the dimensions given
on the right hand side, in this case length divided by time.
Similarly, Darcy's law written for intrinsic permeability is:
Q = A l< PŁ dh (]_2)
u dL
where:
K = intrinsic permeability
o = density [M/L3]
g = acceleration of gravity [L/t2]
,: = viscosity [M/Lt]
by analysis of the dimensions for the quantities in Equation 1-2
[K] - L3/t x .._ M/kt_ ..... _ x L = L2
L2 M/L3 - L/t2 L
From examination of Equations 1-1 and 1-?, it is apparent, that:
K = K - (1-3)
L/t "/Ll
M/l 3 • | ,/t?
-------
Using equation 1-3, the conversion from hydraulic conductivity in
cm/sec to intrinsic permeability in cm2 at 20°C is:
"K = 1 cm/sec x 1.005 x 10~2 gm/cm . sec
0.998 gm/cm3 x 980.7 cm/sec2
K = 1.027 X 10"5 cm2
Conversion from U.S. Geological Survey hydraulic conductivity units in
gallons/day x ft2 or ft/day to oilfield units of intrinsic permeability in
darcys is made in the same way, but is more complicated because the darcy is
defined by an inconsistent mixture of values and at 20°C, whereas the U.S.G.S.
units are defined at 60°F. However, realizing that the conversion is basic-
ally similar to the one shown above, one can accept the conversion values
that have been worked out and are contained in tables such as Table 1-5.
Because it cannot
in any particular case,
been left in nonunitized
group of symbols, but no
priate to the data avail
the user understand how
To assist the reader, an
the end of this chapter.
be anticipated what system of units will be provided
most of the equations in the remaining chapters have
form. That is, the equations include the correct
set of units has been chosen, so that any set appro-
able can be used. This does, however, require that
to accomplish the unitization, as has been explained.
appendix of units and conversion factors is given at
As one example of such unitization, the equation for increase of hydrau-
lic head in the vicinity of an injection well, which is introduced in Chap-
ter 4, will be used. The equation is:
2.25 Tt
[L] (1-4)
4 TT T r<- S
where
Ah = hydraulic head change at radius r and time t [L]
Q = injection rate [L3/t]
T = transmissivity [L2/t]
S = storage coefficient [dimensionless]
t = time since injection began [t]
r = distance from well bore to point of interest [L]
Any set of consistent units can be entered into this equation. For
example, if Q=ft3/t, T = ft2/day, t = days, and r = ft, then Ah will be in
ft. However, if Q = gpm, T = gpd/ft, t = days, and r = ft, then the appro-
priate conversions must be entered to obtain consistent units. In this case,
the conversions are:
10
-------
TABLE 1-5. CONVERSION TABLE FOR HYDRAULIC CONDUCTIVITY UNITS
cm/ sec ! in/sec
1 c~-/sec 1.000 • 1.000 X TO'2
!
1 -i/sec 1 .000 X 102 j 1 . 000
1 r/day 1 .157 X lO'3! 1.157 X 10'5
: ft/sec 30.48 1 30.48 X 10'2
' f:/day 3.528 X lQ-4: 3.528 X lO'6
• opr/ft2 6.791 X lO'2! 6.791 X 10~4
1 cdp/n2 4.716 X lO'5; 4.716 X 10'7
m/day
864.0
8.640 X 104
1.000
2.633 X 104
3.048 X 10-1
58.67
4.075 X 10'2
ft/sec
3.281 X 10'2
3.281
3.797 X 10~5
1.000
1.157 X 10'5
2.228 X 10'3
1.547 X lO-6
ft/ day
2.835 X 103
2.835 X 105
3.281
8.640 X 104
1.000
1.925 X 102
1.337 X ID'1
gpm/ft2
14.72
1.472 X 103
1.704 X lO'2
4.488 X 102
5.194 X 10"3
1.000
6.944 X 10~4
CONVERSION TABLE FOR TRANSMISSIVITY UNITS
m2/sec ; m2/day ft2/min
i
~ -2/sec 1.000 8.64 X 10^_j 6.459 X 102
: v^'da/ 1 .157 X lO'5 : 1 .000
; r-?<'rin 1.548 X 10'^ 1.338 X 102
• ^2-^v 1 .075 X 10'6 : 9.289 X 10'2
' -nr/^t; 2.070 X 10'4 ! 17.88
1 -:;d/ft 1 .437 X 10"7 i 1 .242 X 10'2
^ -'j ^ r r "/
*t/ci; 2.930 X 10'6 : 2.532 X 10"1
7.476 X 1Q-3
1.000
6.944 X 10'4
1.337 X 10-1
9.284 X 10-5
1.892 X lO"3
ft2/day
9.301 X 105
10.76
1.440 X 103
1.000
1.925 X 102
1.337 X 10-1
2.725
gpm/ft
4.831 X 103
5.592 X ID'2
7.480
5.194 X 10-3
1.000
6.944 X 10-4
1.416 X ID'2
qpd/ft
6.957 X 106
80.52
1.077 X 104
7.480
1 .440 X 103
1.000
20.38
gpd/ft2
2.121 X 104
2.121 X 106
24.54
6.464 X 105
7.480
1.440 X 103
1.000
darcy • ft/cp
3.413 X 105
3.950
5.284 X 102
3.669 X 10-"1
70.64
4.906 X 10~2
1.000
-------
TABLE 1-5. (Continued)
CONVERSION TABLE FOR HYDRAULIC CONDUCTIVITY &
INTRINSIC PERMEABILITY UNITS FOR WATER AT 20° C
1 cm/sec
1 ft/day
1 gpd/ft2
1 cm2
1 darcy
cm/sec
1.000
3.528 X 10-4
4.716 X 1Q-5
9.740 X 104
9.613 X 10~4
ft/ day
2.835 X 103
1.000
1.337 X 10-1
2.761 X 108
2.725
gpd/ft2
2.121 X 104
7.480
1.000
2.065 X 109
20.38
cm2
1.027 X lO-5
3.623 X 10'9
4.842 X 10"10
1.000
9.870 X 10"9
darcy
1.040 X 103
3.669 X 10-1
4.906 X 10~2
1.013 X 108
1.000
-------
1 gpm = 1 x 1440 min/day
7.48 gal/ft3
= 192.49 ft3/day
1 gpd/ft = L = 0.1337 ft2/day
7.48 gal/ft3
Equation 1-4 would then be:
Ah = (2.30) (192.49) Q log (2.25 x 0.1337) Tt
(4 TT) (0.1337) T r2 s
= 264 Q log 0.30 Tt
T r2 S
where
Ah = hydraulic head change at radius r and time t [ft]
Q = injection rate [gpm]
T = transmissivity [gpd/ft]
S = storage coefficient [dimensionless]
t = time since injection began [days]
r = radial distance from well bore to point of interest [ft]
A reader interested in a more extensive discussion of units and dimen-
sions can consult one of numerous available texts on the subject, for example,
Taylor (1974), Pankhurst (1964), Ipsen (1960), Sedov (1959), and Murphy
(1950).
-------
REFERENCES - CHAPTER 1
Donaldson, E. C. Subsurface Disposal of Industrial Hastes in the United
States. U.S. Bureau of Mines Information Circular 8212. 1964.
34 pp.
Harlow, I. F. "Waste Problem of a Chemical Company." Indus. Eng. Chemistry.
Vol. 31. 1939. pp. 1345-1349.
Ipsen, D. C. Units, Dimensions, and Dimension!ess Numbers. McGraw-Hill Book
Company, New York. 1960.
Ives, R. E., and Eddy, G. E. Subsurface Disposal of Industrial Hastes.
Interstate Oil Compact Commission, Oklahoma City, Oklahoma. 1968.
109 pp.
Murphy, Glenn. Similitude in Engineering. The Ronald Press Co., New York.
1950.
Pankhurst, R. C. Dimensional Analysis and Scale Factors. Reinhold Publishing
Corporation, New York. 1964.
Reeder, Louis, et. al. Review and Assessment of Deep-Hell Injection of
Hazardous Waste. Final Report for EPA Contract No. 68-03-2013, Program
Element No. 1DB063, Solid and Hazardous Waste Research Laboratory,
Cincinnati, Ohio.
Sedov, L. I. Similarity and Dimensional Methods in Mechanics. Academic Press,
New York. 1959.
Taylor, E. S. Dimensional Analysis for Engineers. Clarendon Press, Oxford
University, London. 1974.
TEMPO. Polluted Groundwater: Some Causes, Effects, Controls, and Monitoring.
U.S. Environmental Protection Agency Publication EPA-600/4-73-001b,
prepared by General Electric TEMPO, Santa Barbara, California, for the
U.S. EPA, Washington, D.C. 1973.
U.S. Environmental Protection Agency. Compilation of Industrial and Municipal
Injection Wells in the United States. EPA-520/9-74-020, Office of
Water Program Operations, Washington, D.C. 2 Vols. October, 1974.
Warner, D. L. Deep-Wells for Industrial Waste Injection in the United States
- Summary of Data. Federal Water Pollution Control Research Series
Publication No. WP-20-10. 1967. 45 pp.
14
-------
Warner, D. L. Survey of Industrial Waste Injection Hells. 3 Vols. Final
Report, U.S. Geological Survey Contract No. 14-08-0001-12280. Univer-
sity of Missouri, Roll a, Missouri. 1972.
Warner, D. L., and Orcutt, D. H. "Industrial Wastewater - Injection Wells
in the United States - Status of Use and Regulation, 1973." in
Underground Waste Management and Artificial Recharge. Jules
Braunstein, Ed. Am. Assoc. Petroleum Geologists, Tulsa, Oklahoma.
1973. pp. 552-564.
-------
APPENDIX - CHAPTER 1
UNITS AND CONVERSION FACTORS
LENGTH
Unit
1 Centimeter
1 Meter
1 Kilometer
1 Inch
1 Foot
1 Yard
1 Mile
Equivalents of First Column
Centi-
meters
1
100
100,000
2.54
30.48
91.44
160,935
Meters
.01
1
1,000
.0254
.3048
.9144
1,609.3
Ki 1 o-
meters
.00001
.001
1
.0000254
.000305
.000914
1.6093
Inches
.3937
39.37
39,370
1
12
36
63,360
Feet
.0328
3.2808
3,280.8
.0833
1
3
5,280
Yards
.0109
1.0936
1 ,093.6
.0278
.3333
1
1 ,760
Miles
.0000062
.000621
.621
.000016
.000189
.000568
1
AREA
Unit
1 Sq. cen-
timenter
1 Sq.
meter
1 Sq. inch
1 Sq. foot
1 Sq. yard
1 Acre
1 Sq. Mile
Equivalents of First Column
Square
Centimeters
1
10,000
6.452
929
8,361
40,465,284
--
Square
Meters
.0001
1
.000645
.0929
.836
4,047
2,589,998
Square
Inches
.155
1,550
1
144
1,296
6,272,640
Square
Feet
.00108
10.76
.00694
1
9
43,560
27,878,400
Square
Yards
.00012
1 .196
.000772
.111
1
4,840
3,097,600
Acres
.000247
--
.000023
.000207
1
640
Square
Miles
--
--
—
--
.00156
1
-------
ir-PE', v .'. -- Con ti nued
VOLUME
Equivalents of First Column
jn i f
C_, . Centime
:_.. veter
_ • t e --
1". S. Ga 1 1 on
I-^p'-ial Ga
C ., . Inch
^ r ^» ^ +-
W • J . • U 'O I,
' p " ^
' i "no*
:?.'- ?GC.
C.,. -out-
er Dav
,, . ^ . ua M on
ier' "in.
[-• :. . Ga 1 1 on
:
-------
APPENDIX -- Continued
WEIGHT
Unit
1 Gram
1 Kilogram
1 Ounce
(Avoirdupois)
1 Pound
(Avoirdupois)
1 Ton (Short)
1 Ton (Long)
Equivalents of First Column
Grams
1
1000
28.349
453.592
907.184.8
1,016,046.98
Kilograms
.001
1
.0283
.454
907.185
1,016.047
Ounces
(Avoir-
dupois)
.0353
35.274
1
16
32,000
35,840
Pounds
(Avoir-
dupois)
.0022
2.205
.0625
1
2,000
2,240
Tons
(Short)
.0000011
.0011
.0000312
.0005
1
1.12
Tons
(Long)
.00000098
.000984
.0000279
.000446
.893
1
co
CONVERSION TABLE
(Gallons per Minute—Gallons per Day—Cubic Feet per Second)
G.P.M.*
10
20
30
40
50
75
100
125
150
175
G.P.D.*
14,400
28,800
43,200
57,600
72,000
108,000
144,000
180,000
216,000
252,000
Sec, Ft.*
0.022
0.045
0.067
0.089
0.111
0.167
0.223
0.279
0.334
0.390
G.P.D.*
10,000
20,000
30,000
40,000
50,000
75,000
100,000
120,000
140,000
160,000
G.P.M.*
6.9
13.9
20.8
27.8
34.7
52.1
69.4
83.3
97.2
111.1
Sec. Ft.*
0.015
0.031
0.045
0.062
0.077
0.116
0.155
0.186
0.217
0.248
(Continued)
-------
APPENDIX - Continued
CONVERSION TABLE -- Continued
G. P . M. *
550
600
650
i ~~~
G.P.D.*
200
?50
300
350
400
---]-- - -- — i
! 288,000
! 360,000
432,000
504,000
; 575,000
648,000
720,000
792,000
864,000
936,000
,008,000
,080,000
,152,000
,224,000
1,296,000
,368,000
,440,000
,728,000
,016,000
2,304,000
2,592,000
2,880,000
.M.
«.,..
Sec. Ft. :
Sec. Ft.*
0.446
0.557
0.668
0.780
0.391
1 .00
1 .11
1 .23
1.34
1 .45
1 .56
1 .67
1.78
1 .89
2.01
2.12
2.23
2.67
3.12
3.57
4.01
4.46
G.P.D.*
180,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
900,000
1,000,000
1 ,200,000
1,400,000
1,600,000
1 ,800,000
2,000,000
2,500,000
3,000,000
3,500,000
4,000,000
4,500,000
5,000,000
10,000,000
G.P.M.*
125.0
138.9
208.3
277.8
347.2
416.7
486.1
555.6
625.0
694.4
833.3
972.2
1111.1
1250.0
1368.9
1736.1
2083.3
2430.6
2777.8
3125.0
3472.2
6944.4
Sec. Ft.*
0.015
0.309
0.464
0.619
0.774
0.928
1.08
1.24
1.39
1.55
1.86
2.17
2.48
2.79
3.09
3.87
4.64
5.42
6.19
6.96
7.74
15.5
Gallons per Minute
j. Gallons per 24-Hour Day
_ubic Feet per Second
-------
APPENDIX - Continued
COMPARISON OF UNITS USED IN PETROLEUM INDUSTRY WITH
UNITS USED BY GROUND WATER INDUSTRY
Ground-Water Industry Unit Equivalent Petroleum Industry Unit
Gallon (gal.) (42 Gallons) 1/42 Barrel (bbl.). . 1 Barrel
9,702 cu. inches
5.615 cu. feet.
Q-gallons per minute (gpm) 34.29 Barrels per day (B/D)
Drawdown in feet (s) Differential pressure= 0.433
pumping level minus static psi/ft of drawdown for water
water level (SWL) with a specific gravity of 1.0
(sa) - actual drawdown
(s^) - theoretical drawdown
of 100% efficient well
Specific capacity (S) Productivity index (P.I.)
gpm per foot of drawdown 79.91 B/D per psi
Permeability: Permeability:
meinzer - gallons per day of 1 darcy - cubic centimeters
water at 60°F per 18.24 per second per square
square foot at 100% centimeter at one dyne
hydraulic gradient per square centimeter
length and.viscosity
of one centipoise.
54.82 mi 11idarcy
18.24 gallons/day/sq. foot 1 darcy
(60°F)
(0.01824 gals/day/sq. foot) 1 mi 11idarcy
Transmissibility: Transmissibility:
1
gpd - ft. at prevailing 20.38 darcy-ft. per centipoise
temperature at 100%
hydraulic gradient 49.07 millidarcy-ft. per centipoise
20
-------
CHAPTER 2
THE GEOLOGIC AND HYDROLOGIC ENVIRONMENT
Knowledge of the geologic and hydrologic characteristics of the sub-
surface environment at an injection well site and in the surrounding region
is fundamental to the evaluation of the suitability of the site for waste-
water injection and to the design, construction, operation and monitoring
of injection wells. In defining the geologic environment, the subsurface
rock units that are present are described in terms of their lithology, thick-
ness, areal distribution, structural configuration and engineering properties.
The chemical and physical properties of subsurface fluids and the nature of
the local and regional subsurface flow system comprise the hydrologic environ-
ment. In addition, resources of. present or potential value are identi-
fied to avoid endangering them through wastewater injection. The characteris-
tics of the geologic and hydrologic environment are defined and discussed in
this chapter with reference to wastewater injection.
INJECTION AND CONFINING INTERVALS
Vertical sequences of rocks that occur in the subsurface are conven-
tionally subdivided by geologists into groups, formations, and members, in
descending hierarchy. That is, members are subdivisions of formations and
formations subdivisions of groups. Use of these terms implies mappable
(traceable) rock subdivisions, based on mineralogy, fossil content, or other
recognizable characteristics. However, such subdivisions may or may not be
entirely suitable when discussing subsurface flow systems, because the engi-
neering properties of porosity and permeability often do not respect geologic
boundaries. This problem was long ago recognized by ground water hydrolo-
gists who developed the terms aquifer, aquiclude, aquitard, and aquifuge to
describe rock subdivisions in terms of their capacity to hold and transmit
water. An aquifer is defined as a formation, group of formations, or part of
a formation that contains sufficient saturated permeable material to yield
significant quantities of water to wells and springs. Conversely, an aqui-
clude stores water, but does not transmit significant amounts. An aquitard
lies between the two previously defined types in that it transmits enough
water to be regionally significant, but not enough to supply a well. An
aquifuge neither contains nor transmits water (Davis and DeWiest, 1966;
Walton, 1970). These same terms could be applied in discussing wastewater
injection, and sometimes are; but other terms are more commonly used. Actual
or potential receiving aquifers are commonly called the injection intervals,
/ones, units, or reservoirs and the intervening strata are referred to as
confining intervals (liquid udes) or semi-confining intervals (aquitards). The
basement sequence of igneous or metanorpnic rock that lies beneath the sedi-
nentary rock cover is generally non-porous and ir"pcrnie
-------
remainder of this text, injection interval will be used to describe the total
vertical interval into which wastewater is being injected and injection zone
will mean a subdivision of the injection interval. Other terminology, as
defined above, will also be used where appropriate.
ROCK TYPES
Rocks are described in terms of their origin and their lithology, the
latter characteristic being defined by their composition and texture. By
origin, the three broad rock types are classified as igneous, metamorphic,
and sedimentary. While nearly all rock types can, under favorable circum-
stances, be capable of acting as injection intervals, sedimentary rocks, par-
ticularly those deposited in a marine environment, are most likely to have
suitable geologic and engineering characteristics. These characteristics are
sufficient porosity, permeability, thickness, and areal extent to permit the
rock to act as a liquid-storage reservoir at safe injection pressures.
Sandstone, limestone, and dolomite are types of sedimentary rock com-
monly porous and permeable enough in the unfractured state to be suitable
injection reservoirs. Naturally fractured limestone, dolomite, shale, and
other rocks may also be satisfactory.
Unfractured shale, clay, siltstone, anhydrite, gypsum, and salt have
been found to provide good seals against upward or downward flow of fluids.
Limestone and dolomite may also be satisfactory confining beds; but these
rocks commonly contain fractures or solution channels, and their adequacy
must be determined in each case.
STRATIGRAPHIC GEOLOGY
Study of the composition, sequence, thickness, age and correlation of
the rocks in a region is stratigraphic geology or stratigraphy. The basic
means of display of data used in stratigraphic studies is the columnar sec-
tion, which is a graphic representation of the rock units present at a loca-
tion or in a region. Figure 2-1 is a generalized columnar section for north-
eastern Illinois. This particular example was selected because it shows a
variety of rock types, is typical of the east-central states, and is easily
interpreted and discussed. Some possible injection intervals in Figure 2-1
are indicated by the fact that they are being used for natural gas storage.
One of these possible injection reservoirs, the Mt. Simon Formation, is the
deepest and is overlain by the Eau Claire Formation, which may contain shale
confining beds. On the other hand, the St. Peter Formation is the shallowest
and is overlain by limestones and dolomites, which are less dependable for
confinement. Therefore, the St. Peter has a lesser potential for wastewater
injection. The Mt. Simon Formation has, in fact, been widely used for waste-
water injection in Illinois, Indiana, Ohio, and adjacent states, whereas no
injection wells have yet been constructed for disposal into the St. Peter
Formation. In areas where there are sandstones in the Eau Claire Formation,
immediately above the Mt. Simon, these can be considered along with the Mt.
Simon Formation as a single injection interval (aquifer). This interval has
been referred to as the Mt. Simon aquifer (Suter and others, 1959) or the
"basal sandstone" (Ohio River Valley Water Sanitation Commission, 1976).
22
-------
Dolomite ond limestone, coorse groyne
\shole, green
20 - 40 .Dolomite ond l.mesfone, gro/ rr.o
i -,uRi ''-1. ui.'Jf kAi !/t !) COMJM'JAR SiClK)!; 0! (AMl;,R!A:i "',; :];:y
CIA*; '•.'!;:A;A r; 'JORIHI AST; R;J ;;! i1;!}!1-,. R; A.'.-. !;:VT
-------
Another means of displaying strati graphic information is the cross sec-
tion. Figure 2-2 is a west-east cross section of southeast Kansas, which
has been constructed from the stratigraphic columns of 15 deep wells. This
cross section was selected to show a typical stratigraphic sequence from the
Kansas-Oklahoma area. In this case, the most promising injection interval
is the Arbuckle Formation, which is widely used for industrial wastewater
and oilfield brine disposal in Kansas and Oklahoma. The Arbuckle is composed
principally of dolomite interbedded with sandstone, as is indicated by the
patterns used in the cross section.
Cross sections show the thickness of rock units along a selected line,
but thickness (isopach) maps are used to show this characteristic over an
area. Figure 2-3 is a map showing the thickness of the Mt. Simon aquifer or
basal sandstone interval in the Ohio River Basin area. As previously dis-
cussed, this basal interval includes the Mt. Simon Formation and sandstones
immediately above it in the Eau Claire Formation. As can be seen in Fig-
ure 2-3, the basal sandstone of the Ohio Valley area is more than 2,500 feet
thick in northeastern Illinois but disappears entirely in northern New York.
Figure 2-4 shows the thickness of the confining beds in the Eau Claire For-
mation that overlie the basal sandstone. Thicknesses range from about 200
feet to over 600 feet. The confining interval is only shown as being present
where the strata are dominantly shale and siltstone. Elsewhere the basal
sandstone is overlain by sandstone, dolomite, or limestone and the effective-
ness and upper boundary of the confining interval become less well defined.
Other factors being equal, the thicker an injection or a confining interval,
the better it will serve its purpose. However, there is no lower limit of
thickness that can be established for either an injection or confining inter-
val in general. Judgement is based on engineering as well as geologic fac-
tors and must be made for each individual case. Examples of such an evalua-
tion will be given later.
Rock units commonly vary in their composition as they are traced later-
ally. Such variations are referred to as facies changes, facies being a
geologic term that means appearance or aspect. For example, Figure 2-5 is
a schematic west-east cross section that shows the lower Eau Claire Formation
changing from a mixture of lithologies in eastern Indiana and western Ohio to
sandstone in central Ohio and to dolomite in eastern Ohio. In this case, for-
mational names also change as the lithology changes. Facies maps show such
variations over an area. Some types of facies maps are ratio maps, percen-
tage maps, and isolith maps. These would show with patterns or contours,
respectively, ratios or percentages of the constituents or the aggregate
thickness of one selected constituent.
Figure 2-6 shows the ratios of shale-siltstones, sandstones,and carbonates
in the Eau Claire confining interval that overlies the basal sandstone (Mt.
Simon aquifer) in the Ohio River basin area. Ratios are only shown where
this interval is more than 50 percent shale-siltstone because, as previously
explained, the effectiveness of confinement and upper boundary of the inter-
val are less certain as the amounts of sandstone and carbonates in the confin-
ing unit increase. Comparison between Figures 2-5 and 2-6 shows that both
indicate a rapid change in the lithology of the Eau Claire Formation from
24
-------
N t M A M A ANTIC II N t
-t'f
4~i~-
J--1 «-
t KOKt t BASIN
y
HASIN lOCHC^CJKLti BASIN
FIGURE 2-2. DIAGRAMMATIC WEST-EAST CROSS SECTION OF SOUTHEAST
KANSAS SHOWING STRUCTURAL CONFIGURATION AND STRATI-
GRAPHY (ADAPTED BY GOBEL, 1971, FROM LEE AND MERRIAM,
1954).
-------
ro
CTl
FIGURE 2-3. THICKNESS OF THE BASAL SANDSTONE OHIO RIVER BASIN AND
VICINITY (OHIO RIVER VALLEY WATER SANITATION COMMISSION
1976).
-------
FIGURE 2-4. THICKNESS OF THE EAU CLAIRE CONFINING INTERVAL OHIO
RIVER BASIN AND VICINITY (OHIO RIVER VALLEY WATER
SANITATION COMMISSION 1976).
-------
WEST
EAST
ro
00
ROME FM (dolomite)
EAU CLAIRE
FM
Rome sandstone facies
FIGURE 2-5. SCHEMATIC WEST-EAST SECTION OF THE EAU
CLAIRE AND EQUIVALENT ROME STRATA
(JANSSENS, 1973, P. 10).
-------
shale-siltstone
100
50%
sandstone
carbonate
2-6 RATIO OF LITHOLOGIES IN THE EAU CLAIRE CONFINING INTERVAL
OHIO RIVER BASIN (OHIO RIVER VALLEY WATER SANITATION COM-
MISSION 1976).
-------
west to east across Ohio. Fades maps of injection intervals can, similarly,
be useful in showing changes that affect their quality for injection purposes.
STRUCTURAL GEOLOGY
Structural geology is concerned with the folding and fracturing of rocks
and the geographic distribution of these features.
Structural geologic characteristics of a region and, on a smaller
scale, of a particular site are significant because of their role in influen-
cing subsurface fluid flow, the engineering properties of rocks, and the lo-
calization of mineral deposits and earthquakes. Sedimentary rocks may be
folded into synclines (downward or trough-like folds) or anticlines (upward
folds). Synclinal basins of a regional scale (hundreds of miles) are viewed
as particularly favorable for wastewater injection as discussed in Chapter 5.
On a smaller scale, petroleum occurs naturally in closed anticlinal folds.
Anticlines are also used for temporary underground storage of natural gas.
Therefore, many anticlinal areas in petroleum-producing states and in regions
where gas storage is practiced are not available for wastewater injection.
On the other hand, it has been suggested that wastes less dense than the
water in the injection interval could be stored in anticlines, as is natural
gas (Figure 2-7), if the anticlines were not otherwise used. Injection of
wastes denser than water into closed synclinal areas might also be
good practice because the wastes would tend to remain trapped there.
This concept has not been employed to date, but may merit consideration in
the future.
Faults are fractures in the rock sequence along which there has been
displacement of the two sides relative to one another. Such fractures may
range from inches to miles in length, and displacements are of comparable
magnitudes. Faults may occur singly or in systems so complex that it is
not possible to completely define them.
It is known, through experience, that faults may act either as barriers
to fluid movement or as channels for fluid movement. However, little is
known in detail about how and why some faults are barriers and others are
flow channels. In theory, no fault in a sedimentary rock sequence will be
an absolute harrier, but a fault may be of so much lower permeability than
the aquifer it cuts that it is, for practical purposes, a barrier. Since
it will seldom be possible for a geologist to initially state whether a
fault is a barrier or a flow path, it would be appropriate to consider any
significant fault to be a flow path for purposes of preliminary evaluation of
its importance. If, as a consequence of this initial assumption, the fault
would be an environmental hazard it would then be necessary to either abandon
the project or to test the fault directly by methods that will be described
later. A significant fault might be defined as one that is of sufficient
length, displacement, and vertical persistence to provide a means of travel
for injected wastewater to an undesirable location. This question is one that
will have to be answered by qualified geologists and engineers on the basis
of their best judgement, after a review of the data for a particular site.
30
-------
Well B
Well C
Well D
ghfcr than formation water
Sandstone containing interstitial formation water
Injected waste (heavier than formation water) ~
FTGURf 7-1. SCHEMATIC ILLUSTRATION OF THE CONCEPT OF
STORING LIGHT WASTES IN ANTICLINES AND
DENSE WASTES IN SYNCLINES (ALVERSON, 1970).
-------
Empirical observations and considerable research have, within the past
decade, led many earth scientists and engineers to the conclusion that, under
the proper circumstances, subsurface fluid injection can stimulate movement
along some faults. When movement occurs, stored seismic energy is released;
that is, an earthquake occurs. Although much remains to be learned about
this subject, it appears that the circumstances favorable to earthquake gen-
eration are relatively rare. The mechanism of earthquake generation and
means of anticipating such an occurrence will be expanded upon in later sec-
tions.
Fractures also exist along which there has been no movement. This type
of fracture may be referred to as a crack or joint to distinguish it from a
fault. Cracks and joints are important sources of porosity and permeability
in some aquifers but can be undesirable when they channel fluids rapidly
away from an injection well in a single direction or where they provide flow
paths through confining strata. The presence and nature of fractures is de-
termined by examination of rock cores obtained during drilling, by well log-
ging and testing methods, and from experience with other deep wells drilled
in the same region.
Structural geologic data are displayed in maps, cross sections, and
other types of figures. Major structural features are displayed in tectonic
maps (regional scale) or structural geologic maps (subregional or local
scale). Figure 2-8 shows the location of prominent structural geologic fea-
tures in southwest Alabama, which include the Hatchetigbee anticline, the
Jackson fault-Klepac dome^, the Mobile graben^, and the Gilbertown, Coffee-
ville-West Bend, Walker Springs, Pollard, and Bethel fault zones. Other sig-
nificant structures are domal anticlines near Chatom, Citronelle, South
Carl ton, and the salt dome at Mclntosh. Industrial disposal wells have been
drilled in the Mobile graben (T. 1 S., R. 1 E., Mobile County) and on the
north flank of the Mclntosh salt dome (T. 4 N., R. 1 E., Washington County),
which is also in the Mobile graben (see Tucker and Kidd, 1973 for further
details). Figure 2-9 is a west-east structural cross section across the
Mobile graben and the Klepac dome, illustrating the nature of faulting asso-
ciated with the graben.
Maps that show the elevation of a particular stratigraphic horizon rel-
ative to a selected datum are structure contour maps. Structure contour maps
allow an estimate of the approximate depth to the mapped unit, the direction
and magnitude of dip of the unit, and also show the location of faults and
folds that may influence decisions concerning the location and monitoring of
a well. Figure 2-10 is a map of the configuration or structure of the top
IA dome is a symmetrical anticline, with the strata dipping more or less
equally in all directions from the center. Salt domes, which are common in
the Gulf Coast Region have been formed by the upward movement of a core of
salt.
p
A graben is a block of strata that has been downdropped between two
faults, as is illustrated in Figure 2-9.
32
-------
L4-.4—t-J
PlCKENi
-------
West
East
564
5,000
01
I/I
c
o
0)
E
o
a>
0)
a>
10,000
Jackson Fault
15,000
262
EXPLANTION
Undiffentiated
O
UJ
U
U
Qi
UJ
CL
Q_
Lower Tuscaloosa j Q
UJ
Undifferentiated J LU
a:
Haynesville and Cotfon
— Valley Undifferentiated
FIGURE 2-9. WEST-EAST CROSS SECTION ACROSS THE MOBILE
GRABEN AND KLEPAC DOME (TUCKER AND KIDD,
1973).
-------
•r,-m >>*;'•; \
!-;'«. \\,' .'Vr
STRUCTURAL CONFIGURATION ON THE TOP OF THE WILCOX GROUP IN A PORTION OF SOUTH-
WESTERN ALABAMA (ALVERSON, 1970).
-------
of the Wilcox Group in southwestern Alabama. The datum for the map is sea
level. A wastewater injection well present in T. 1 S., R. 1 E., is injecting
into a sand bed in the Wilcox Group. It can be seen that the depth to the
top of the Wilcox Group is about 2,600 feet in the center of the township
(elevation of the Wilcox is about -2,600 feet and the ground elevation in
that area is less than +50 feet). The general regional dip of the top of
the Wilcox Group is roughly 40 feet per mile to the southwest, but the dip
is steeper and more westward in the center of the township in which the well
is located. It can also be seen that the well is between two major faults
that enclose a downdropped block, previously identified as the Mobile graben.
ENGINEERING PROPERTIES OF ROCKS
In order to make a quantitative evaluation of the mechanical response
of the subsurface environment to wastewater injection, the engineering prop-
erties of the reservoir rocks must be determined or estimated. Properties
classed here as engineering include porosity, permeability, compressibility,
temperature, and state of stress. Each of these is described in detail
below.
Porosity
Porosity is defined as:
= _y_ (dimensionless) (2-1)
vt
where = porosity, expressed as a decimal fraction
Vv = volume of voids
Vt = total volume of rock sample.
Porosity is also commonly expressed as a percentage. Porosity may be
a total porosity or effective porosity. Total porosity is a measure of all
void space; effective porosity is based on the volume of interconnected voids.
Effective porosity better defines the hydraulic properties of a rock unit,
since only interconnected porosity is available to fluids flowing through the
rock. The difference between total and effective porosity is often not
known, or it may be small, but the distinction should be kept in mind.
Porosity may also be classified as primary or secondary. Primary poro-
sity includes original intergranular or intercrystalline pores and the poro-
sity associated with fossils, bedding planes, and so forth. Secondary
porosity results from fractures, solution channels, and from recrystalliza-
tion and dolomitization. Intergranular porosity occurs principally in uncon-
solidated sands and in sandstones. Intergranular porosity in a sandstone
depends on the size distribution, shape, angularity, packing arrangement,
mineral composition, and degree of natural cementation of the grains. It can be
measured in the laboratory on consolidated rock cores taken during drilling.
Core analysis of unconsolidated sands is difficult, but techniques have
recently been developed by which it is possible to obtain cores from such
36
-------
formations and to perform laboratory analyses upon them with some assurance
that the results are representative of the in situ formation properties
(Mattax and Colthier, 1974). Porosity contributed by fractures and solution
channels is also difficult to measure in the laboratory. A major deficiency
of core analysis is the fact that the samples being measured comprise only a
small fraction of the interval of interest and may not be representative of
the rock in place. To determine the porosity of strata in place, various
borehole geophysical methods that will be discussed later can be used.
Porosities in sedimentary rocks range from over 35 percent in newly
deposited sands to less than 5 percent in 1 Unified sandstones. Dense lime-
stones and dolomites may have almost no porosity. Porosity is not a direct
measure of the overall reservoir quality of a rock unit, but a reservoir with
high porosity is better than one with low porosity. This is because the
greater the amount of pore space, the smaller will be the area into which the
waste will spread. Also, although there is no universal relation between
porosity and permeability, an increase in porosity often correlates with
increased permeability in a particular aquifer or injection interval. Figure
2-11 is a contour map of the average porosity of the basal sandstone (Mt.
Simon aquifer) in the Ohio River basin area. Average porosities range from
over 20 percent to less than 5 percent. A porosity of over 20 percent is
high for a lithified sandstone and a porosity of less than 5 percent is very
low.
The average porosity multiplied by the total thickness of reservoir rock
yields the pore volume per unit area. This number provides a means of read-
ily comparing the storage capacity of a formation at various locations. Con-
tour maps of pore volume have been called isoval maps. The data in Figures
2-3 and 2-11 could be combined to obtain an isoval map.
No criteria have been developed for classification of the quality of
a reservoir based on its pore volume, and this may not be possible. A thick
sandstone with a low porosity can have the same pore volume as a thinner
sandstone with a high pore volume, yet the reservoirs will not be of equal
quality for injection purposes. However, in general, a reservoir with a high
pore volume will be better than a reservoir with a low pore volume.
The permeability of a rock is a measure of its capacity to transmit a
fluid under an applied potential gradient. As with porosity, intergranular
permeability is influenced by the grain properties of rocks that are com-
posed of grains (sands, sandstones, siltstones, shales, etc.). However,
whereas porosity is not theoretically dependent on grain size, perneabi 1 i t y
is strongly dependent on this property. The smaller the grains, the larger
will be the surface area exposed to the flowing fluid. Since it. is the f fic-
tional resistance of the surface area th.it lowers the flow rate, the smaller
the grain si/e the lower the pernoabi 1 i t •/. Shales, which are iisrned frori
extremely snail qrains, have alnost no penseab i 1 i ty . This is why shales are
selected as confining intervals. As with offer tive porosity, per:»eabi 1 i t y
also results fVoir i ntercorme'. t ed solution rhls and fractures as well as
t ror i 'i 1 1 > is i jfini >t t >•'} i n t er>. : r a r • . .
-------
oo
03
FIGURE 2-11. AVERAGE POROSITY OF THE BASAL SANDSTONE OHIO RIVER
BASIN AND VICINITY (OHIO RIVER VALLEY WATER SANI-
TATION COMMISSION 1976).
-------
Quantitatively, permeability is expressed by Darcy's law, one form of
which is:
Apg dh
where Q = flow rate through porous medium
A = cross-sectional area through which flow occurs
v - fluid viscosity
p - fluid density
L = length of porous medium through which flow occurs
h = fluid head loss along L
g = acceleration of gravity
K = coefficient of- permeability
When the properties of fluid density and viscosity appear in the Darcy
equation, as in Equation 2-2, the flow capacity of the medium alone is mea-
sured and J_s referred to as the coefficient of permeability. If cgs units
are used, K will be expressed in cm . The unit of permeability used in oil-
field work is the darcy or the millidarcy, which is one-thousandth of a dar-
cy. The darcy is defined by:
Ł = SE ^L [L2] (2-3)
A dp
where p = ugh = pressure and the specified conditions are:
1 darcy = ^ cm^/sec x 1 centipoise x 1 cm
1 cm2 x 1 atmosphere
A simpler form of Darcy's law used in shallow ground water studies is:
K = 9 dL [L/T] (2-4)
A dh
where K ~-: hydraulic conductivity, and other symbols are as previously de-
fined.
The density and viscosity of the aquifer fluids do not appear in Equa-
tion ?-4 because they are incorporated as part, of the hydraulic conductivity
value. In cgs units, hydraulic conductivity is in en/ sec. The U.S. Geolo-
gical Survey unit for hydraulic conductivity is feet/day /ind formerly w^s
-------
Permeability values from core samples of units used for wastewater
injection or petroleum production range from several darcys to less than one
millidarcy, but an average value of less than 10 millidarcys for an overall
interval would be considered to be very low, whereas a value of 100-1,000
millidarcys would be good to very good. Shales, which are considered to be
suitable confining strata, have permeabilities in the order of 10"3 to 10~6
millidarcys, or thousands of times less than an adequate injection interval.
In evaluating the suitability of an injection or confining unit, reser-
voir thickness is as important as permeability. Saturated reservoir thickness
multiplied by hydraulic conductivity is the transmissivity, which can be in-
terpreted as the rate at which fluid at the existing fluid viscosity and den-
sity is transmitted through a unit width of aquifer at a unit hydraulic gra-
dient. The unit of transmissivity (T) is darcy-feet/centipoise or milli-
darcy-feet/centipoise. A suitable injection interval will usually require
transmissi vities measured in thousands of mi llidarcy-feet/centi poise. As
with porosity, permeability can be measured on core samples in the laboratory
or by tests performed in boreholes.
It should be mentioned that permeability may be dependent on the chemis-
try of the permeating fluid. Reservoirs that contain clay minerals may have
a lower permeability to water than to air. The degree of permeability re-
duction to water as compared with air is termed the water sensitivity of a
reservoir (Baptist and Sweeney, 1955). It is also important to note that the
permeability of a reservoir to two or more fluids of differing capillary
properties is not the same as the permeability to a single fluid as has been
discussed above. When two fluids, for example, water and air or water and oil,
are flowing simultaneously through a rock, the permeability to either is
lower than it would be if the rock were fully saturated with the one fluid.
This is one reason why oils or entrained gas should be removed from a waste-
water before it is injected.
Compressibility
The compressibility of an elastic medium is defined as:
1 (2-5)
where 3 = compressibility of medium [ pressure"!]
V = volume
p = pressure
The compressibility of an aquifer includes the compressibility of the
aquifer skeleton and that of the contained fluids. (See also Compressibility,
under Properties of Subsurface Fluids.) To account for the compressibility
of both the fluid and the aquifer, petroleum engineers often arbitrarily use
a compressibility (c), which ranges from 5 x 10~5 to 10 x 10~° psi'l as com-
pared with the compressibility of water alone which is about 3 x 10"° psi"1
(Amax, Bass, and Whiting, 1960). Van Everdingen (1968) uses this procedure
40
-------
in arbitrarily selecting a fluid and rock compressibility of 6 x 10"^ psi ^
for the example calculations that he presents.
A parameter related to compressibility is the storage coefficient, which
is defined by Lohman (1972):
S = !],!( ir.n ,'•'- (-. S : , I; . f'i. / • '.'''I.'V- ; •, i.,'1 ' 'i ; !:P « ' '; ' '. ' ..
-------
lO"^ psi~l) = 2.7 10~5. Since this value must be too low, it will arbitrarily
be multiplied by 2.5 to obtain a more reasonable value of 7.4 x 10"^. In com-
parison with this, Lehman's suggested value of 10~6 per foot of aquifer
thickness gives a storage coefficient of 1 x 10"^. None of these procedures
yields an accurate value, but they all help to determine the order of magni-
tude within which the storage coefficient should lie.
Temperature
The temperature of the aquifer and its contained fluids is important
because of the effect that temperature has on fluid properties. The tempera-
ture of shallow ground water is generally about 2° to 3° greater than the
mean annual air temperature. Figure 2-12 shows the approximate temperature
of ground water in the United States. Below the shallow ground water inter-
val, the temperature increases at an average rate of about 2°F per 100 feet
of depth, but the rate of increase is quite variable and may be from as much
as 5°F to less than 1°F per 100 feet of depth (Levorsen, 1967). This rate
of temperature increase with increasing depth is termed the geothermal grad-
ient. The geothermal gradient is obtained from temperature measurements made
in deep wells and is calculated by dividing the difference between the temper-
ature at a point in the subsurface and the mean annual surface temperature by
the depth to the observation point. Figure 2-13 is an example of a geothermal
gradient map. Geothermal gradient maps for the United States have been pre-
pared by the American Association of Petroleum Geologists, Tulsa, Oklahoma,
and can be obtained from the organization.
Using data such as that in Figure 2-12 and 2-13, the temperature at a
specific location and depth can be estimated. For example, at a site where
the mean annual surface temperature is 60°F and the gradient is 1.5° per
100 feet of depth, the estimated temperature at a depth of 3,000 feet would
be about 105°F.
State of Stress
In a sedimentary rock sequence, the total normal vertical stress in-
creases with depth of burial, under increasing thicknesses of rock and fluid.
It is commonly assumed, and the validity of the assumption can easily be
verified, that the normal vertical stress increases at an average of about
1 psi/ft of depth. The lateral stresses may be greater or less than the
vertical stress, depending on geologic conditions. In areas where crustal
rocks are being actively compressed, lateral stresses may exceed vertical
ones. In areas where crustal rocks are not in active compression, lateral
stresses should be less than the vertical stress. The basis of estimating
lateral stress prior to drilling of a well is hydraulic fracturing data from
nearby wells and/or knowledge of the tectonic state of the region in which
the well is located. The tectonic state of various regions is only now being
determined. For example, Kehle (1964) concluded, as a result of hydraulic
fracturing data from four wells, that the stresses at the well locations
in Oklahoma and Texas were representative of an area that was tectonically
in a relaxed state. In contrast, Sbar and Sykes (1973) characterized much
of the eastern and north-central United States as being in a state of active
tectonic compression.
42
-------
Degrees Fahrenheit
FIGURE 2-12. APPROXIMATE TEMPERATURE OF GROUND WATER IN THE
UNITED STATES AT DEPTHS OF 30 TO 60 FEET (COLLINS,
1925).
-------
CONTOUR MAP OF GEOTHERMAL GRADIENTS IN SW. U.S.
CONTOUR VALUES ARE IN
DEGREES PER 100 FEET
MEAN SURFACE TEMP. = 74° F
FIGURE 2-13.
GEOTHERMAL GRADIENT CONTOURS IN PARTS OF
TEXAS, LOUISIANA, AND ADJACENT STATES.
CONTOUR VALUES ARE IN DEGREES FARENHEIT
PER 100 FEET OF DEPTH (WELEX, UNDATED).
-------
In order to predict the pressure at which hydraulic fracturing or fault
movement would be expected to occur, it is necessary to estimate the state
of stress at the depth of the injection horizon. On the other hand, deter-
mination of the actual fracturing pressure allows computation of the state
of stress (Kehle, 1964).
The general equation for total normal stress across an arbitrary plane
in a porous medium is (Hubbert and Willis, 1972):
S = p + a [F/L2] (2-7)
where S = total stress
p = fluid pressure
a = effective or intergranular normal stress.
Effective stress, as defined by Equation 2-7, is the stress available to
resist hydraulic fracturing or the stress across a fault plane that acts to
prevent movement on that fault. The equation shows that, if total stress
remains constant, an increase in fluid pressure reduces the effective stress
and a decrease in fluid pressure .increases effective stress. When the effec-
tive stress is reduced to zero by fluid injection, hydraulic fracturing oc-
curs. In the presence of a fault, along which shear stress already exists,
fault movement will occur before normal stresses across the fault plane are
reduced to zero.
Further discussion concerning the state of stress and hydraulic frac-
turing will be presented in. the section on hydraulic fracturing.
Properties of Subsurface Fluids
Chemistry --
Judgement as to whether wastewater may or may not be permitted to be
injected into a rock unit depends, in part, on the chemistry of the contained
water. Chemical analyses of subsurface water are also useful for correlation
of stratigraphic units, interpretation of subsurface flow systems, and calli-
bration of borehole logs. In wastewater injection, the chemistry of con-
tained water is important because of the possibility of reaction with in-
jected wastewater. This latter topic is discussed in detail in Chapter 6.
In order to evaluate the chemistry of aquifer water, it is necessary
to obtain samples after a well is drilled; samples from previously drilled
wells may provide a good indication of what will be found. Geophysical logs
are also useful for estimating the dissolved solids content; of aquifer water
in intervals that are not sampled. The range of dissolved ions that may be
present in - tiKi'.inc Meter'' i nat. ions characterize the
-------
TABLE 2-1. COMMON WATER ANALYSES PERFORMED
ON SUBSURFACE WATER SAMPLES
DETERMINATION
Alkalinity
Aluminum
Barium
Calcium
Chloride
Conductivity
Hydrogen ion (pH)
Hydrogen sulfide
Iron
Magnesium
Manganese
Potassium
Sodium
Specific gravity
Sulfate
Total Dissolved Solids
ROUTINE ANALYSIS
X
X
X
X
X
X
X
X
X
X
X
X
INJECTION INTERVAL WATER
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
46
-------
general geochemical nature of the water. The additional analyses suggested
for an injection interval water are for the purpose of predicting the reacti-
vity of that water with injected water. They would be selected on the basis
of reactions that are suggested by the chemistry of the wastewater. Samples
of water taken from shallow fresh-water aquifers should be analyzed more com-
pletely for minor elements so that their baseline quality is well established
and the presence of any later-introduced contaminants can be detected.
One means of illustrating the quality of water in a subsurface reservoir
is by use of a map in which the concentration of dissolved solids or another
selected measurement is shown with contours (isocon map). Figure 2-14 shows
the chloride concentrations of Arbuckle Formation water in Kansas and Okla-
homa. The map shows that water in the Arbuckle is less saline around outcrop
areas where it has been diluted by fresh water entering the outcrop. Away
from the outcrop, water in the Arbuckle is very saline, which is one reason
that the formation has been widely used as an injection interval in those
two states.
Viscosity --
Viscosity is the ability of a fluid to resist flow, and is an important
property in determining the rate of flow of a fluid through a porous medium.
The common unit of viscosity is the poise, or the centipoise, which is one
one-hundredth of a poise. Figure 2-15 shows the variation in viscosity of
water with temperature and salinity. Both temperature and dissolved solids
content can have a significant effect. In most cases, the effects will tend
to be offsetting in subsurface waters, since temperature and dissolved solids
content both commonly increase with increasing depth.
Density --
The density of a fluid is its mass per unit volume. Liquid density
increases with increased pressure and decreases with increased temperature.
However, that water changes very little within the range of pressures and
temperatures of interest. For example, the density of water decreases only
0.04 gm/cm^ between 60°F and 210°F (Figure 2-16), and increases only about
0.04 gm/cm^ from 0 to 14,000 psi (Figure 2-17). A more important influence
on water density is the total dissolved solids content. Figure 2-18 shows
the effect of various amounts of sodium chloride on specific gravity (or
density)J Since natural brines may differ significantly from sodium chlo-
ride solutions, it may be desirable to develop empirical relationships be-
tween density and dissolved solids as was done by Bond (1972) for the Illi-
nois basin (Figure 2-19).
^Specific qravity is the ratio of the mass of a body to that of an
equr.il volume of pure water, so for practical purpose1;, in the metric system,
the riunier ic:d 1 values of density and specific; (iravity arc equal. Spe;.ifu.
(iivivity, however, is d inieri'-. iunl ess .
-------
KANSAS
" ~ OKLAHOMA
LEGEND
| Arbuckl* outcrop
j Prt-Pinnsylvanlon tubcrop
] Arbucklt absent owing to prs-
' Pennsylvanian erosion (Pre-
Simpson In northeast Kansas)
FIGURE 2-14.
MAP OF THE CHLORIDE CONCENTRATIONS IN
WATERS OF THE ARBUCKLE FORMATION IN
KANSAS AND OKLAHOMA (COLLINS, 1975,
P. 332).
48
-------
1.0
180,000 PPM
240,000 PPM
68 100 150 200 250
RESERVOIR TEMPERATURE (°F)
300 350
A riJNCTIO'i 0!'
-------
en
O
"- I.U 1 U
o
O
<° 1.000
or 0.990
UJ
< 0.980
Ł 0.970
UJ
> 0.960
i-
3 0.950
UJ
* 0.940
> 0.930
-------
PROPERTIES OF LIQUID WATER
05
n
-H.
LU
S
o
1J.
0
ai
o-
1.01
1.00
0.99 -
0.98 -
0.97 -
0.96 -
0.95 -
0.91 t
0.90
0
500
1000
1500
-5 0
TEMPERATURE ( C)
FIGURF ?-!?. srrcinc VOLUME or WATER AS A nncium or
.ATijRf AND PRESSURE (ElSCflBrRG AND KAU7MA.NN,
P. iR(,i.
-------
en
ro
LJL
o
O
(D
CL
O
O
O
LU
CL
0
50,000
100,000 150,000
TOTAL SOLIDS (PPM)
200,000 250,000
FIGURE 2-18.
SPECIFIC GRAVITY OF WATERS VERSUS
TOTAL SOLIDS IN ppm (DATA FOR NaCl
SOLUTIONS) PIRSON, 1963, P. 39).
-------
280,000
260,000 -
240,000 —
220,000 —
200,000 —
| 180,000 —
Ol
E
Q 160,000 —
13
O
Q
> 140,000 —
—i
O
1/3
C/5
_, 120,000
100,000 —I
80,000
60,000
40,000
20,000
FIGURE 2-19.
RELATION BETWEEN RELATIVE DENSITY AND DISSOLVED
SOLIDS CONTENT OE BRINES IN DEEP AOUH !RS Of THE
ILLINOIS BASIN (BOND, 197?).
1 00
I T I I
1,04 1 06 1 08 1.10
Rf 1 ATlVf, [)[ MSI TV, p
1.1? 1 14
1 18
-------
Pressure --
A knowledge of fluid pressure in the unit proposed for wastewater in-
jection is important. Fluid pressure can be measured directly in the bore-
hole at the depth of the injection horizon, usually by performing a drill-stem
test, which will be described later. Fluid pressure at the injection horizon
can also be measured indirectly by determining the static water level in the
borehole, then computing the pressure of the fluid column at the depth of
interest.
Figure 2-20 shows how fluid pressure increases with depth in a well
bore filled with fresh water having a specific gravity of 1.0. When the aver-
age specific gravity of the water or wastewater is other than 1.0 the rate of
pressure increase varies accordingly. For example, if a well bore is filled
with formation water with a dissolved solids content of 65,000 mg/liter and
a specific gravity of 1.035, then fluid pressure increases at a rate of 0.45
psi/ft, and would be 450 psi at the bottom of a 1,000-ft-deep water-filled
well. This is an average gradient (Levorsen, 1967, p. 394), but the actual
gradient can vary because of water density variations and other causes and
should be determined for any specific site.
Although instances of truly anomalous formation pressure are likely to
be relatively rare at sites selected for wastewater injection, the existence
of unusually high or low pressures and the possible reasons for their exis-
tence should be recognized.
Hanshaw and Zenn (1965) list ten possible causes of anomalous pressure
as (1) high hydraulic head (2) rapid loading and compaction of sediments (3)
tectonic forces (4) temperature effects (5) osmotic membrane phenomena (6)
"fossil" pressure corresponding to previous greater depth of burial (7)
infiltration of gas (8) mineral phase changes involving water (9) solution or
precipitation of minerals (10) water from magmatic intrusions. Of these mech-
anisms, the first five are the most commonly mentioned. Large scale injection
or extraction of fluids could also be added to the list.
Abnormally high pressures are common in deep wells of the Gulf Coast
(Dickinson, 1953). Berry (1973) concluded that abnormally high pressures in
the California Coast Ranges are a result of tectonic forces. Hanshaw (1972)
discussed natural osmotic effects and their relation to subsurface wastewater
injection.
Compressibility --
All pore space in strata used for wastewater injection is already fluid
filled and injected wastewater is emplaced by displacing and compressing
aquifer water and by compressing the skeleton of the aquifer.
The compressibility of water varies both with temperature and pressure,
as is shown in Figure 2-21. For problems in wastewater injection, compressi-
bility will generally be within the range of 2.8 to 3.3 x 10"6 psi"', and
3.0 x 10~6 psi"' is a reasonable value to assume in most cases.
54
-------
xKV
^/A
h 1 ft—
1
I
\~
1
1
r~
i
i
i
r"
i
i
i
r~
i
i
i
r~
i
i
i
i
i
r~
i
i
l~
i
i
4
1
I_
7
7
/
7
7
7
7
7
7
0.433-^
0.433
0.433
0.433
0.433
0.433
0.433
0.433
0.433
0.433
7
4 33 psi/IO feet
-------
en
en
2 3.6
PRESSURE-PSIA
1000
2000
30(30
40156
•
5
6000
50
100 150 200
TEMPERATURE-°F
250
300
FIGURE 2-21. COMPRESSIBILITY OF WATER
(KATZ AND COATS, 1968, P. 93).
-------
Subsurface Flow Systems
Understanding of the ultimate fate of injected wastewaters and their
environmental effect depends, in part, on knowledge of the regional and local
subsurface flow system. Earlier in the chapter it was shown that the fluid
pressure in a well filled with saline water or a saturated series of sedimen-
tary rocks increases vertically at an average of about .45 psi per foot of
depth below the water surface as a result of the weight of the water alone.
If the water in a subsurface reservoir were static (not moving) and had the
same density everywhere, it would rise to the same level in all wells that
tap the aquifer. In that case, the pressure in a horizontal aquifer would
be the same everywhere. Water in some deeply buried rock units has been
found to be nearly static. If the water is moving, the water levels will
vary. They will be higher in wells nearest the source of flow and lower at
progressively greater distances away from the source of flow, showing that
hydrodynamic conditions exist. The surface formed by water levels in wells
tapping an aquifer that is confined by an aquiclude or aquitard is a piezo-
metric or potentiometric surface, which can be shown with a profile (Fig-
ure 2-22) or a contour map. The fluid potential at a point in an aquifer is
defined as (Hubbert, 1953):
= fluid potential
g = gravitational constant
p = fluid pressure
p = fluid density
z = elevation at the point of pressure measurement relative
to a selected datum (usually sea level).
If both sides of Equation 2-8 are divided by g, the gravitational constant,
then the fluid potential is expressed as elevation, and the basis for the
validity of using measured water levels to define the potentiometric surface
is shown. Equation 2-8 is necessary because pressure measurements are usually
made in wells of the type used for injection rather than water level measure-
ments, as is common in water wells. Pressure is then converted to potential
in feet and added to the elevation of the measurement: point to obtain total
potentia 1.
Muure ?-23 is a potentiometric map of the sequence: of Ordnvician aqe
strata in the mid-continent area. The upper portion o! the Arbuckle Group is
included in this unit.. Lines drawn perpend i rul ar to equ ipotentia 1 lines indi-
i ft to the direction of fluici flow, which is shown hy arrow-., in Pi (jure ?-?3.
/Jhile the •, ion i t icance of parts of F'i'jijre ,'•'-,'•''•! is no' ; ert.ain, an ii'ipor t.an'.
f,.n ' *ha' (an be obtained ''r<)<" the ":au insofar us waste injection is con-
cerned, is that, the potential t;r,,ulienf is .'fry low in Kansas and i"iu h of
'H I a li:.)i-.a . Ih'i' sii'jMt"". t', *hi.yf f lui'11. in "h'1 Ordnvi; las r-jf.k', ;i:i:<- '''Ovine; : S1"' ' ' * S1 /'I'M ". ! '"' ': .' >a '. 1 '
-------
Ground surface
en
CO
PJezometric
surface
Impermeable
v
Confined
J2L
aquifer
Impermeable
FIGURE 2-22. DIAGRAMMATIC PROFILE OF THE PIEZOMETRIC (POTENTIOMETRIC) SURFACE OF A CONFINED
AQUIFER IN WHICH FLOW IS FROM RIGHT TO LEFT, AS DEFINED BY THE WATER LEVELS IN
THREE WELLS (TODD, 1959, P. 79).
-------
NATIONAL PETROLEUM COUNCIL STUDY
FUTURE PETROLEUM PROVINCES hT"
OF THE UNITED STATES
MID-CONTINENT (AREA 7)
23 0 ?S 50 71 100 |25 ,50 175 200 MILES
COKIOUR INTERVAL VARIABLE
DIRECTION OF KYDRODYNAMIC FLOW
FRONTJL OUCHITJ THRUST FABLT
HICH IICLE FAULT hjchuits on do.« Ih.o.n sidi
UNCLASSIFIED FAULT
PRECAMBRIAN ROCKS
-^^/—X-\':"-J}.-L..
FIGURE 2-23. POTENTIOMETRIC SURFACE MAP OF CRDOVIC1AN
AGE ROCKS IN THE MID-CONTINENT AREA (LARSON
1971).
-------
not one in which wastewater injection into Ordovician rocks is likely to be
practiced in any case, because of the great depth at which these rocks occur
in that area. The calculation of flow rates from potentiometric maps is
covered in Chapter 4.
Subsurface Resources
It is the goal of both regulatory agencies and well operators to prevent
jeopardizing fresh ground water, oil or gas, coal, and other subsurface re-
sources. Therefore, the occurrence and distribution of all significant sub-
surface resources must be determined. This determination is made by refer-
ence to published reports and by consultation with public officials, companies,
and individuals familiar with subsurface resources of the area. Also, the
actual drilling of the well will show the location and nature of resources
present in the subsurface at the well site.
In reviewing the occurrence of subsurface resources, the locations,
construction, use, and ownership of all wells, both shallow and deep within
the area of influence of the injection well should be determined. The plug-
ging record for all abandoned deep wells should be obtained to verify the
adequacy of such plugging. In states where oil has been produced for many
years there are often areas where wells are known to have been drilled, but
for which no records are available, and there are also wells which are loca-
ted but for which plugging records are not available or for which plugging
is known to have been inadequate. Documenting the status of deep wells near
the injection well may be the most important step in site evaluation for in-
jection wells in areas that are or have been active oil or gas provinces.
These wells provide the greatest hazard for escape of wastewater or formation
water from otherwise well-confined aquifers.
60
-------
CHAPTER 2
REFERENCES
Alverson, R. M. Deep Well Disposal Study for Baldwin, Escambia, and Mobile
Counties, Alabama. Geological Survey of Alabama Circular 58, University
of Alabama. 1970. 49 pp.
Amyx, J. W., Bass, D. M., and Whiting, R. L. Petroleum Reservoir Engineering.
McGraw Hill Book Co., New York. 1960. 610 pp.
Baptist, 0. C., and Sweeney, S. A. Effect of Clays on the Permeability of
Reservoir Sands to Various Saline Waters. Wyoming, U.S. Bureau of Mines
Rept. Inv. 5180. 1955.
Berry, F. A. F. "High Fluid Potentials in California Coast Ranges and their
Tectonic Significance." Bulletin American Association Petroleum Geolo-
gists. Vol. 57, No. 7. 1973. pp. 1219-1249.
Bond, D. C. Hydrodynamics in Deep Aquifers of the Illinois Basin. Illinois
State Geological Survey Circular 470. 1972. 72 pp.
Buschbach, T. C. Cambrian and Ordovician Stratigraphy of Northeastern
Illinois Basin. Illinois State Geoloaical Survey Circular 470. 1972.
72 PP;
Collins, A. G. Geochemistry of Oil field Waters. Elsevier Publishing Co.,
New York. " 1975.
Collins, W. D. IeŁiŁe_r^jtu_re of Water_Avai_l a_bje__f_qr Industrial Use jn the
U n i ted Jyta tes . U.S. GeoTo gTcaT Su r~ve~y "WaTer- Su ppTy Pa'peV" "5 20"- F /
r92~5T"pp.~97-104.
Davis, S. M., and DeWiest, R. J. M. Hydrogeplogy . John Wiley and Sons, Inc.,
New York. 1966. ' " ....... "
Dickinson, George. "Geological Aspects of Abnormal Reservoir Pressures in
the Gulf Coast, Louisiana ." Anericin Asspc. Petroleum Geologists Bulle-
tin, Volume 39, No. 2. 1953. '" "~
Eisenherq, [)., and W. Kauzmann. The Structure an;! Proper' .ies of Water.
0> ford Univprsit.y Press, ;,'ew Vori , 'Jew' York . }cif.t<. ;J1')6 ;)}).
-------
Gobel, E. D. "Southeast Kansas-Northeast Oklahoma-Southwest Missouri." in
Future Petroleum Provinces of the United States -- Their Geology and
Potential. Ira Cram, Ed. American Assoc. Petroleum Geologists Memoir
15, Tulsa, Oklahoma. 1971. pp. 1088-1097.
Hanshaw, B. B. "Natural Membrane Phenomena and Subsurface Waste Emplacement."
in Underground Waste Management and Environmental Implications. T. D.
Cook, Ed. American Assoc. of Petroleum Geologists Memoir 18, Tulsa,
Oklahoma. 1972. pp. 308-315.
Hanshaw, B. B., and Zenn, E. "Osmotic Equilibrium and Overthrust Faulting."
Geol. Soc. Am. Bulletin. Vol. 76. No. 12. pp. 1379-1385.
Hubbert, M. K. "Entrapment of Petroleum Under Hydrodynamic Conditions."
Bulletin American Association Petroleum Geologists. Vol. 37. August,
1953. pp. 1954-2026.
Hubbert, M. K., and Willis, D. G. "Mechanics of Hydraulic Fracturing."
in Underground Waste Management and Environmental Implications. T. D.
Cook, Ed. American Assoc. Petroleum Geologists Memoir 18. 1972.
pp. 239-257.
Jannssens, A. Stratigraphy of the Cambrian and Lower Ordovician Rocks in
Ohio. Ohio Division of Geological Survey Bulletin 64. 1973.
Katz, D. L., and D. L. Coats. Underground Storage of Fluids. Ulrich's
Books, Inc., Ann Arbor, Michigan. 1968. 575 pp.
Kehle, R. 0. "The Determination of Tectonic Stresses through Analysis of
Hydraulic Well Fracturing." Journal Geophys. Research. Vol. 69, No. 2.
1964. pp. 259-273.
Larson, T. G. "Hydrodynamic Interpretation of Mid-Continent." in Future
Petroleum Provinces of the United States - Their Geology and Potential.
I. H. Cramm, ed.. American Assoc. Petroleum Geologists Memoir 15,
Tulsa, Oklahoma, pp. 1043-1048.
Lee, Wallace, and Merriam, D. F. Cross Sections in Eastern Kansas. Kansas
Geological Survey Oil and Gas Inv. No. 12. 1954.
Levorsen, A. I. Geology of Petroleum. W. H. Freeman and Co., San Francisco.
1967.
Lohman, S. W. Ground-Water Hydraulics. U.S. Geological Survey Prof. Paper
708. 1972. 70 pp.
Mattax, C. C., and Clothier, A. T. "Core Analysis of Unconsolidated and
Friable Sands," Society of Petroleum Engineers, SPE Paper No. 2986.
October, 1974.
62
-------
Ohio River Valley Water Sanitation Commission. Evaluation of the Basal Sand-
stone for Wastewater Injection Ohio Valley Region. Ohio River Valley
Water Sanitation Commission, Cincinnati, Ohio. 1976.
Pirson, S. J. Handbook of Well Log Analysis. Prentice-Hall, Inc., Englewood
Cliffs, N. J. 1963. 326 pp.
Sbar, M. L., and Sykes, M. L. "Contemporary Compressive Stress and Seismicity
in Eastern North America: An Example of Intra-Plate Tectonics."
Geol. Soc. of Am. Bulletin. Vol. 84, No. 6. 1973. pp. 1861-1882.
Todd, D. K. Ground Water Hydrology. John Wiley, New York. 1959.
Tucker, W. E., and Kidd, R. E. Deep-Well Disposal in Alabama. Geological
Survey of Alabama Bulletin 104. 1973.
Van Everdingen, A. F. "Fluid Mechanics of Deep-Well Disposals." in Subsur-
face Disposal in Geologic Basins - A Study of Reservoir Strata. J. E.
Galley, ed. American Assoc. Petroleum Geologists Memoir 10. 1968.
pp. 32-42.
Walton, W. C. Groundwater Resource Evaluation. McGraw-Hill Book Company,
New York. 1970.
Welex. Basic Concepts of Well Log Interpretation. Welex, Houston, Texas.
undated. 35 pp.
-------
CHAPTER 3
ACQUISITION AND USE OF GEOLOGIC
AND HYDROLOGIC DATA FOR INJECTION WELL SITE EVALUATION
In order to predict the performance of injection wells and their effects
on the environment, the types of information described in Chapter 2 must be
estimated prior to well construction, and the actual geologic characteristics
and values for rock and fluid properties determined during well construction
and testing.
After the geologic and engineering data are obtained, they may be eval-
uated qualitatively by experienced technicians or they may be used in calcu-
lations to predict the probable performance of a well constructed at the site.
Examples of such calculations are given in the latter part of the chapter.
DATA OBTAINABLE FROM EXISTING
SOURCES PRIOR TO DRILLING
Prior to drilling an injection well, the geologic and engineering
data needed for site evaluation are obtained from sources such as are shown
in the figures and tables presented in Chapter 2. The information in those
figures and tables has, of course, come from geological surveys, geophysical
surveys, previously drilled wells, etc.; if it has not been compiled
in usable form on maps, cross sections, tables, etc., then this may be neces-
sary. Basic information for previously drilled wells is available in most
states through state geological surveys, state oil and gas agencies, state
water resources agencies, and some universities. States with notable oil
and gas production are particularly good sources. In addition, private com-
panies in the petroleum industry acquire and sell well logs, other subsur-
face data,and services. In some cases it may be feasible to go to individual
oil companies or consultants for subsurface data that are not publicly avail-
able. Companies and individuals are usually cooperative in releasing infor-
mation that is not considered confidential.
It is possible to obtain considerable original subsurface geological
information without drilling by the use of surface geophysical methods, in-
cluding seismic, gravity, magnetic, and electrical surveys. However, because
of the nature of the data that can be obtained and its cost, it can be anti-
cipated that surface geophysical surveys will not be widely used for injection
well site studies. For this reason surface geophysical methods will not be
discussed further here. A popular introductory text that describes the avail-
able geophysical survey methods has been written by Dobrin (1976).
64
-------
DATA OBTAINABLE DURING WELL CONSTRUCTION AND TESTING
Rock Samples
Most deep wells drilled today are drilled by rotary drilling rigs.
Rotary drilling rigs use two basic types of drilling bits: rock bits and core
bits.
Rock bits grind the strata into small chips (commonly 1/8 in. - 1/2 in.
across) that are usually carried from the hole by a viscous drilling mud,
but sometimes by water or air. The chips are periodically collected, usually
after each five or ten feet of new hole, washed, and examined with a low-
power, binocular microscope. The methods for collection, examination, and
description of such samples are presented in a reference edited by Haun and
LeRoy (1958). Soft, unconsolidated clays will not yield chips, but will
break down into mud while unconsolidated or soft sandstones will break down
into individual grains when drilled. Samples are of only small value when
drilling such rocks. Table 3-1 is the lithologic description of cuttings
from one depth interval obtained during the drilling of an injection well in
Alabama. The sampling interval in this case was 30 feet.
Core bits are open in the center so that, as the bit moves downward,
a cylindrical plug of rock is cut and remains. This plug rises inside a
hollow tube or core barrel in which it is held and raised to the surface.
Cores from wells of the type under discussion range in size from about 1 to
5 inches, but the most common diameter is 3 1/2 inches. The length of inter-
val that can be cored at one time depends on the length of the core barrel,
which ranges from 20 to 90 feet. Cores are usually taken only from intervals
of interest for injection or confinement because coring is generally much
more expensive than drilling with a rock bit.
Cores are taken because they yield geologic and engineering information
not otherwise available. Fractures, bedding features, solution cavities and
other characteristics can be seen, and laboratory measurements of porosity,
permeability, and other engineering properties can be made. Figures 3-1 a
to 3-lc show some of the geologic features visible in cores. Figure 3-2 is
a photograph of a piece of whole core (3 1/2 in. diameter) from a sandstone
reservoir. Vertical and horizontal plugs (1 in. diameter) have been cut from
the core for porosity and permeability analysis. Plugs are taken as often
as every foot to obtain accurate average values for the entire tore. Some-
times pieces of whole core are tested, particularly in the case of limestones
with solution channels or confining beds with very low permeability. Pro-
cedures for core handling and analysis have been recommended by the American
Petroleum Institute (1960). Geological descriptions of cores arc prepared
similarly to those for cuttings, but since a continuous sample1 of the forma-
tion is available, much more detail t.an be included. Lib IP 3-v1 shows typical
laboratory data obtained from <) 30-foot core taken from t he- Mt . Simon F'or::;,;-
t. ion i n 111 i no i',.
F'on.'M f ions of unconso 1 ida ted s
-------
TABLE 3-1. EXAMPLE OF DESCRIPTIONS OF DRILLING
CUTTINGS OBTAINED FROM ABOVE AND AT
THE TOP OF THE WILCOX GROUP IN A
WASTE INJECTION WELL IN ALABAMA
(TUCKER AND KIDD, 1973).
Stauffer Chemical Company D.W. #1
SW 1/4 sec. 7, T. 1 S., R. 1 E.
(N along W line 2056.3 ft then E 868.2 ft)
Mobile County, Alabama
GSA #3374
Elev. 29.9 ft. GL
41.4 ft. DF
Samples collected at 10-foot intervals beginning at 40 feet, changing to 30-
foot intervals at 70 feet.
2,440-2,470-Ctgs:
2,470-2,500-Ctgs:
Claystone, light-bluish-gray and some light
olive-gray and very light yellowish gray, sili-
ceous, glauconitic, micaceous, trace pyrite,
microfossils; shale, light-olive-gray and
light-greenish-gray; sand, colorless to pale-
yellowish-orange, fine to very coarse, subang-
ular to rounded, quartzose, glauconitic; lime-
stone, brownish-gray, indurated, sandy, quartz-
ose, glauconitic; trace lignite, trace pyrite;
abundant Foram fragments from above; other lime
from above; shell fragments.
Same with increase in greenish-gray shale, san-
dy, micaceous, glauconitic; also increase in
brown limestone and shell fragments.
Wilcox Group?-Sample top
2,500-2,530-Ctgs:
2,500-2,530-Ctgs:
Sandstone, light-olive-gray, calcareous cement,
very fine to medium grained, predominantly
fine, quartzose, glauconitic; sandy limestone,
yellowish-gray, fine-grained, quartzose, glau-
conitic; shale, greenish-gray to light-olive-
gray, sandy, micaceous, calcareous in part;
sand, colorless to very light gray, very fine
to medium, fine predominant, subangular to
rounded, quartzose, glauconitic, micaceous;
limestone, brownish-gray, indurated, sandy,
quartzose, glauconitic; shell fragments,
Foram fragments; trace pyrite.
Same; predominantly sandstone and sandy lime-
stone with some sandy shale.
66
-------
\
FIGURE 3-1. PHOTOGRAPHS OF CORES
LS, SOLUTION CHANNELS, AND VUGS IN DOLOMITE. (b) FOSSILIFEROUS LIMESTONE.
-------
FIGURE 3-1. PHOTOGRAPH OF CORE
(c) LIMESTONE WITH REPLACEMENT OF FOSSILS AND FILLING OF FRACTURES
BY CALCITE CRYSTALS.
-------
FIGURE 1-?. WHOLE CORF OF MT. SIMON SANDSTONE FROM HfilCH
VERTICAL AND HORIZONTAL PLUGS HAVF \WM CUT.
-------
TABLE 3-2. LABORATORY CORE ANALYSIS DATA FROM THE
MT. SIMON FORMATION IN ILLINOIS3
Sample
Number
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
Note:
Depth
(feet)
3154.5
3155.5
3156.6
3157.5
3158.5
3159.5
3160.5
3161.5
3162.5
3163.5
3164.5
3165.5
3166.5
3167.5
3168.5
3169.5
3170.5
3171.5
3172.5
3173.5
3174.5
3175.5
3176.5
3177.5
Permeability
(millidarcys)
Horizontal
6.9
<0.10
<0.10
0.17
0.26
<0.10
1.9
<0.10
2.3
0.43
12.
3.1
0.31
7.8
8.5
5.0
6.2
3.4
10.
1.4
11.
8.5
2.6
0.74
Vertical
0.11
0.17
<0.10
0.31
0.72
<0.10
0.12
<0.10
0.98
0.46
0.12
1.1
0.44
0.79
5.4
3.2
3.6
1.2
2.5
0.46
2.0
1.5
0.91
<0.10
Porosity
(percent)
6.4
6.4
9.7
8.6
8.3
8.1
9.6
8.7
8.1
6.2
8.2
14.7
10.7
10.0
9.9
7.2
6.9
8.3
12.2
8.9
8.0
8.2
7.7
5.9
aMt. Simon Core No. 15 3148.0 - 3178.0
70
-------
into the borehole on a cable. When the sidewall sampler is in position, the
bullets are fired into the borehole walls. The bullet and its contained sam-
ple remain attached to the sampler by two heavy wires and are retrieved by
pulling the bullet from the borehole wall. The samples are normally 7/8 in.
to 1 3/4 in. in diameter and 1 in. to 1 3/4 in. long. Up to 30 samples can
be taken by a single gun. Samples can also be taken in hard formations by
this type of sidewall device, but better results have been obtained by using
a sidewall diamond core slicer that cuts a triangular core one inch in depth
and three feet long. Sidewall cores can be taken when it is desired to sample
intervals not cored during drilling.
Formation Fluid Samples
Samples of water from subsurface formations can be obtained from deep
wells, before they are completed, by use of formation testing devices, by
swabbing, and by gaslift. At times formation pressures will bring water to
the surface from artesian aquifers.
Drill-stem testing is a technique whereby a zone in an open borehole is
isolated by an expandable packer or packers and fluid from the formation al-
lowed to flow through a valve into the drill pipe. See the section on Drill-
Stem Testing on Page 89.
The basic drill-stem test tool assembly is normally attached to the
lower part of a string of drill pipe and consists of:
1. A rubber packing element or packer which can be expanded
against the hole to segregate the annular sections above
and below the element.
2. A tester valve to (a) control flow into the drill pipe,
that is, to exclude mud during entry into the hole and
(b) to allow formation fluids to enter during the test;
an equalizing or bypass valve to allow pressure equali-
zation across the packer(s) after completion of the flow
test; and pressure recording equipment.
Figure 3-3 illustrates the procedure for testing the bottom section of
a hole. While going in the hole, the packer is collapsed, allowing the dis-
placed mud to rise as shown by the arrows (a). After the pipe reaches bottom
and the necessary surface preparations have been made, the packer is set (com-
pressed and expanded); this isolates the lower /one from the rest, of the open
hole (b). The compressive load is furnished by slacking off the desired
amount of drill string weight, which is transferred to the anchor pipe below
the packer.
The tester valve is then opened and the i'-.old ted section i ", exposed tn
the low pressure inside the empty, or nearly emply', drill pipe, formation
fluids ran then enter the pipe1, as shown in the sounui picture (b)- ' -ie
time during which fluids are entering the drill stem testinq tool is talli'd
'he flow period. After the flow period, (tie ;losed in pressure valve is shut
iind the formation pressure allowed to buiH !••.<> I j;< (< '' . Ir; a dual ' ;•-,•] ;i
-------
RUNNING IN
TTT
FLOWING
FORMATION
FORMATION
CLOSED IN
EQUALIZING
PRESSURE
REVERSE
CIRCULATING PULLING OL)T
(a)
(b)
(c)
(e)
(f)
FIGURE 3-3. FLUID PASSAGE DIAGRAM FOR A CONVENTIONAL
OPEN-HOLE, SINGLE-PACKER, DRILL-STEM TEST
(EDWARDS AND WINN, 1974).
72
-------
pressure test, the flow period and closed-in period are repeated. After the
final closed-in period, the tester valve is closed in order to trap any fluid
above it, and the bypass valve is opened to equalize the pressure across the
packer (d). Finally, the setting weight is taken off and the packer is pulled
free. The fluid in the drill pipe may then be circulated out to the surface as
shown in (e), or the reverse circulating step may be bypassed and the pipe
pulled from the hole until the fluid-containing section reaches the surface (f).
As each successive pipe section is removed, its fluid content may be examined.
Although the test described above is a common type, there are variations
of this procedure, two of which are shown in Figure 3-4. The straddle packer
test is necessary when isolation from formations both above and below the test
zone is necessary. Such a situation commonly arises when it is desired to
test a zone previously passed by. The second common variation utilizes per-
forations in casing (Figure 3-4).
Tests through perforations are necessary when it is desired to check a zone
that has been cased-off without testing or in order to retest a zone after
casing has been emplaced.
Formation testing devices are also available which can be lowered into
the borehole on a wire line rather than on a drill pipe. In this case, the
sample is limited to the amount that can be contained in the testing device
(up to about 5 gallons).
Swabbing is a method of producing fluid similar to pumping a well. In
swabbing, fluid is lifted from the borehole through drill pipe, casing, or
tubing by a swab that falls freely downward through the pipe and its contained
fluid, but which seats against the pipe walls on the up-stroke, drawing a vol-
ume of fluid above it as it is raised. Swabbing is preferable to drill-stem
testing where unconsolidated formations cause testing to be difficult. Swabbing
may also be used in conjunction with drill-stem testing to increase the volume
of fluid obtained. The advantage of swabbing is that it can be continued until
all drilling mud has been drawn from the pipe, thus allowing the chemistry of
the formation water sampled to reach a steady state. This procedure helps to
insure that a representative sample of formation water is obtained.
Fluid samples can be obtained by injecting gas under pressure into
WCM. The pressure of gas forces the fluids in the well to rise to the ;
face, thus the name gas-lift sampling.
WelJ Logs
Individuals have different concents of what is "leant by a borehole or
well loq, because of the variety of types of logs that, are used. It. is prob-
ably host to consider a log as any tabular record or nraphiui 1 portrayal of
drilling conditions or subsurface features observed in .1 hire-hole. This is
consistent, with the Glossary of r^nlo';1/ f American rm
-------
GENERAL PROCEDURE
(A) STRADDLE PACKER
TEST
(D) TESTING THROUGH
PERFORATIONS IN
THE CASING
FIGURE 3-4. SCHEMATIC ILLUSTRATION OF TWO DRILL-STEM
TEST CONDITIONS (MODIFIED AFTER KIRKPATRICK,
1954).
74
-------
One possible classification of the general types of logs would be:
1. Sample (cuttings and core) logs
2. Driller's logs
3. Drill ing time logs
4. Mud logs
5. Geophysical logs
A. Electrical logs
B. Elastic wave logs
C. Radiation logs
D. Other
6. Miscellaneous logs
A. Caliper logs
B. Dipmeter logs
C. Deviation logs
D. Production-injection logs
Sample Logs --
Sample logs are prepared from rock cuttings and cores as discussed
above. The tabulated descriptions themselves form a log and they are often
used to prepare a visual strip log or columnar section as shown in Figure 2-1.
Driller's Logs --
In the early days of drilling, the driller's log was the principal well
record kept. It recorded the types of formations encountered, any pertinent
fluid flows or oil and gas shows observed, and other related operational re-
marks. While these records appear crude by present standards, they were con-
sidered to be very informative at the time. Such logs are still frequently
encountered as the only available source of data in old areas. The geologic
descriptions of various formations may be quite colorful and full of expres-
sions unique to either or both the particular area and driller involved.
The current rotary driller's log is filled out daily by each driller as
a record of the operations, materials used, and progress which occurred during
his working hours (tour). It is largely used to inform office personnel of
daily occurrences, to provide operational data, and to serve as a legal record
of the contractor's compliance with the operator's instructions as set forth
in their agreement or contract. The hourly breakdown of time spent on various
operations is also used to compute the amount of the contractor's invoice.
Ordinarily, the rock formation type (such as sand, shale, lime, etc.) is the
only geological information recorded, if any.
Driller's logs can be very important in determining the source of prob-
lems that occur Idler during well operation and in resolving uncertainties
with regard to exactly how subsurface facilities are installed. Table 3-3
summarizes a part of the construction history oi the Roichold Chenicals Incor-
porated well as prepared f'ron driller's logs.
-------
TABLE 3-3. PORTION OF THE CONSTRUCTION HISTORY OF
THE REICHOLD CHEMICALS INCORPORATED WELL,
ALABAMA (TUCKER AND KIDD, 1973)
Drilling Engineer's Log
Reichold Chemicals, Incorporated
Reichold Research Waste Disposal Well No. 1
Holt, Tuscaloosa County, Alabama
5-26-70: Spudded 4:00 p.m.
5-27-70: 8:00 a.m.-dril1 ing 20-inch conductor hole at 40 feet.
9:00 a.m.-shut down and repair rig.
8:30 p.m.-resumed drilling. Drilled for 6 hours 20-inch conductor
hole at 68 feet.
5-28-70: 8:00 a.m.-shut down to repair rig.
8:00 a.m. to 3:00 p.m.-repair rig. Work on swivel, replace belts on
pump and re-align, take air chamber off of rig pump, and replace
gasket. Drain mud tanks and refill with city water. Welding on
rig.
3:00 p.m. to 4:00 p.m.-dril1 ing 20-inch hole to 73 feet.
4:00 p.m. to 8:00 p.m.-repairing rig.
8:00 p.m. to 9:00 p.m.-cut off 24-inch casing and prepare to run 16-
inch casing.
9:00 p.m.-running 16-inch casing. Hit bridge. Rig up swage to wash
down.
11:00 p.m.-Halliburton on location.
11:30 p.m.-unable to wash and work casing past 34 feet. Pulled 16-
inch casing out of hole. Went in hole with bit.
5-29-70: 12:15 a.m.-reaming 20-inch hole.
7:00 a.m. to 10:00 a.m.-running 16-inch casing. Hit tight spot at
45 feet. Could not work casing past that point.
10:30 a.m.-rigged up Halliburton. Began reaming and pumping cement
at 11:20 a.m. Ran 45.65 feet of 16-inch H-40 65 Ib/ft. casing.
Cemented with 75 sacks of Portland/A cement and 75 sacks of Pozmic A
cement with 2% calcium chloride. Plug down at 12:00 noon with re-
turns to surface.
12:00 p.m. to 8:00 p.m.-waiting on cement.
8:00 p.m.-cut 16-inch casing and m'ppled up flow lines to pits.
11:00 p.m. to 12:30 a.m. (5-30-70)-dril1 ing cement and washing to
bottom of hole.
5-30-70: 12:30 a.m. to 11:00 a.m.-dril1 ing 13 3/4-inch hole.
11:00 a.m.-jet pits and fill same with fresh water.
12:30 p.m. to 8:00 p.m.-drilling 13 3/4-inch hole at 114 feet.
3:00 p.m. to 9:00 p.m.-drilling 13 3/4-inch hole. Ran Straight Hole
Test. Hole deviation 7 degrees.
9:00 p.m.-pulled out of hole. Laid down 2 stabilizers and near bit
reamers. Pick up string reamer and 9 3/8-inch bit.
76
-------
Dril1 ing Time Logs --
A drilling time log is often kept by the driller when hole depth ap-
proaches a zone of particular interest. Such a record is quite useful for
precisely locating formations or porous zones. Abrupt changes in drilling
rate will immediately indicate a change in lithology although the cuttings
may not reach the surface for some time.
Mechanical devices which furnish a continuous record of drilling prog-
ress are also in common use. The record obtained is quite accurate and in-
cludes an accounting of all non-drilling time. Two lines are obtained, as
shown in the sample chart of Figure 3-5. The left hand track furnishes the
foot-by-foot drilling rate by recording a diagonal line (to the left and up-
ward) as each foot is drilled. The offsets to the right occur at intervals
of five feet. Non-drilling time is shown by the deflections to the right on
the right hand track. The net drilling time is obtained by subtracting any
non-drilling time from the total interval.
Mud Logs --
Mud logging, as the term is used here, refers to the continuous analysis
of the drilling mud for oil and gas content. This procedure is widely used
in exploratory drilling, and affords an extra tool for detecting the presence
of oil and gas. In mud logging, a portion of the drilling mud is diverted
from the return flow line and inspected for the presence of oil and gas. The
instruments used for detecting and measuring the quantities of hydrocarbons
in the mud are commonly contained in a trailer which is set up at the drilling
s i te.
The discovery of hydrocarbons is not normally an objective when drilling
an injection well; however, in areas where oil or gas may be present mud log-
ging can be employed to decrease the possibility of bypassing these resources
or to avoid the safety hazard that exists in continuing to construct a well
within an open gas-bearing reservoir.
Geophysical Logs --
After a well has been drilled, a variety of logging tools are available
that can be used to produce a record of the geophysical properties of the for-
mations penetrated and their contained fluids. In such logging, a probe is
lowered into a well at the end of a wire cable and measurements made and auto-
matically recorded at. the surface. The geophysical properties that are mea-
sured include electrical resistivity and conductivity, ability to transmit and
reflect sonic energy, natural radioactivity, hydrogen ion content, temperature,
density, etc. These geophysical properties are then interpreted in terms of
litholoqy, porosity, fluid content, and chemistry. Table ;•!-••"! lists many cur-
rent ijeophys i ca 1 well loqqiriq met. hods, the properties 'hey neasur", and their
;nsu 1 i < ; '",a P''r
; '.r, i ' • i ii • 1 i', * ed j p ] a )i i e •!••', h y their' ' f,i de n.ir> •. !''•' • t; < ' ''i
-------
A Line in drilling operations column
moves to the left indicating that
driller got on bottom with new bit and
started drilling at 11:26. Total trip time,
as indicated by "Trip Action", 3 hours
and 17 minutes.
R This is the way a connection looks
on the Geolpgraph chart. The drill-
er raised the drill pipe from bottom at
12:03, broke out the kelly, picked up a
single pipe (adding it to the drilling
string), picked up the kelly and resumed
drilling. This operation required 11 min-
utes, and the driller has written the
depth of the hole, at that time, on the
chart. Thus, every connection is a con-
venient datum for determining the depth
of any drilling or down-time break,
either immediately above or below.
Ł A 4-foot hard streak was encount-
ered at 5,235 feet, as indicated by
the increased spacing of the foot marks
on this time chart.
^ A connection was made at 5.259
feet and a vertical test was run at
this point to determine the vertical devi-
ation of the hole. The driller has noted
on the chart that the test was actually
taken at 5,250 feet and the deviation was
l/i degree. The vertical test and connec-
tion required 34 minutes
C Soft bed was drilled from 5,266 to
5,269 feet. Because of the thinness
of this bed, no core or drill stein test
was attempted.
p This section represents 5 feet of
drilling. Note that every 5 feet the
base line is offset for 1 foot, making a
convenient marker for determining the
depth of significant drilling changes.
Connection was made at 5,287 feet-
Note similarity to the record at "B".
H
A hard streak was encountered
from 5,288 to 5,290 feet.
I At 5,290 feet, the formation soft-
ened, drilling continued to 5,300
feet where the driller was given orders
to cease drilling and circulate for
samples.
I Circulating for samples started at
6:39 as indicated by movement of
the line to the right. After circulating
for 35 minutes, samples showed stain
and odor, and a drill stem test was
ordered.
FIGURE 3-5.
TYPICAL MECHANICAL DRILLING LOG RECORD
(GATLIN, 1960, P. 196).
78
-------
TABLE 3-4. GEOPHYSICAL WELL LOGGING METHODS AND THEIR
APPLICATIONS (MODIFIED AFTER JENNINGS AND
TIMUR, 1973).
Method
Property
Application
CsL
I—
0
-------
TABLE 3-4. (CONTINUED)
o
RADIAT]
Qi
LU
1—
O
Method
Gamma Ray
Spectral
Gamma Ray
Gamma -Gamma
Neutron-Gamma
Neutron-Thermal
Neutron
Neutron-Epi ther-
mal Neutron
Pulsed Neutron
Capture
Spectral Neutron
Gravity Meter
Ultra-Long Spaced
Electric Log
Nuclear Magnetism
Temperature Log
Property
Natural radioactivity
Natural radioactivity
Bulk density
Hydrogen content
Hydrogen content
Hydrogen content
Decay rate of thermal
neutrons
Induced gamma ray
spectra
Density
Resistivity
Amount of free hydro-
gen; relaxation rate
of hydrogen
Temperature
i
1
Appl ication
Shales and nonshales; shali-
ness
Lithologic identification
Porosity, lithology
Porosity
Porosity; gas from liquid
Porosity; gas from liquid
1
Water and gas/oil saturations;)
reevaluation of old wells
i
Location of hydrocarbons;
1 ithology
Formation density
Salt flank location
Effective porosity and
permeability of sands; poro-
sity for carbonates
Formation temperature
80
-------
SOME GEOPHYSICAL WELL LOGGING SERVICES AVAILABLE FROM THREE
COMPANIES PROVIDING WELL LOGGING SERVICES. EQUIVALENT TYPE
LOGS ARE LISTED ON THE SAME LINE ACROSS THE TABLE.
dELEX
•',';'<-- L<:-~
-••-' ' ' ;:•'• : : t-c tr i c Loq
.:;" I r -U/.:*: ion Guard Loq
V» i nci ty Loci
i *pd Acou^ic Velocity Log
' r i nrlei-' Loq
i v'-ocraf" Loq
i ted Density Locj
S i -:,"' aneous Gdnna Ray-Neutron Log
S i'!f: Aa i 1 Neutron Locj
__JLO_MPAN_Y
SCHLUMBERGER
Electrical Log
Induction Electrical Log
Dual Induction Laterolog
Laterolog -3, Laterolog -7
Microlog
Microlaterolog
Proximity Log
Sonic Log
BHC Sonic Log
Ampii tude Log
Variable Density Log
Formation Density Log
Compensated Formation Density
Log
Gamma Ray-Neutron Log
SNP
DRESSER - ATLAS
Electrolog
Induction Electrolog
Dual Induction Focused Log
Laterolog
Mini log
Micro-Laterolog
Proximity Log
Acoustilog
BHC Acoustilog
Fraclog
Variable Amplitude Density Log
Densilog
Compensated Densilog
Gamma Ray-Neutron Log
Epithermal Sidewall Neutron Log
-------
available logging methods is so great, those used in logging a well must be
carefully selected to provide the desired information at an acceptable cost.
Local practice in the particular geographic area is a valuable guide, since
it represents the cumulative experience obtained from logging many wells.
Some of the objectives in logging injection wells will generally be the de-
termination of: lithology; bed thickness; amount, location and type of poro-
sity; and salinity of formation water. In order to achieve these objectives,
a commonly chosen suite of logs will include a gamma ray log, a focused re-
sistivity log, and one or more porosity measuring logs selected from among
the various radiation and elastic wave logs. Some other frequently used geo-
physical logs include the spontaneous potential (SP) and nonfocused electric
logs, along with miscellaneous logs such as the caliper log and the tempera-
ture log.
Figures 3-5a, 3-6, and 3-7 are intervals from a sonic log, a Laterolog-
gamma ray-neutron log, and a temperature log run in a wastewater disposal
well in northern Illinois. On the Laterolog-gamma ray-neutron log, the con-
tact between the Eau Claire Formation and the Mt. Simon Formation is shown
at 3108 feet where it was picked by the Illinois Geological Survey. However,
it is apparent from the gamma ray log that, for engineering purposes, the
shale confining interval terminates at 2900 feet and that sandstones usable
for injection begin at 2900 feet. The combined Mt. Simon Formation and the
sandstones in the lower Eau Claire Formation comprise the Mt. Simon aquifer
or "basal sandstone." From the sonic log, it can be seen that the first sand-
stone interval from 2900 to 2940 feet has an average interval transit time of
about 72 microseconds per foot. Using tables provided by the logging company
(Schlumberger, 1972a) and a matrix velocity of 19,500 ft/second, the average
porosity of this sandstone body is estimated as 15 percent. The temperature
log shows a temperature of about 83.5° F from 2900 to 2940 feet, and from the
Laterolog (Figure 3-5), the resistivity of this interval is about 40 ohm-met-
ers. From the Archie equation (Schlumberger, 1972) the formation factor F is
45 and the resistivity of the formation water is 0.625 ohm-meters. Figure
3-8 shows that sodium chloride water with a resistivity of 0.625 ohm-meters
has a dissolved solids content of about 8,000 ppm at 83.5° F. Actually, the
formation water salinity is about twice the calculated value because the
Laterolog yields incorrectly high resistivities when run in low-salinity mud,
as is the case here. An induction log would yield more accurate results in
such a situation. This example illustrates some of the principal uses of
borehole geophysical logs in conjunction with the evaluation of geological
conditions in wastewater injection wells. Further uses will be covered in
Chapter 8 on well monitoring. Keys and Brown (1973) give a more complete dis-
cussion and bibliography of the application of borehole geophysical logs to
wastewater injection than is possible here. Other excellent references are
Pirson (1963), Lynch (1962), and Haim and LeRoy (1958).
Miscellaneous Logs --
Among the logs classified here as miscellaneous logs are caliper logs,
which measure borehole diameter; dipmeter logs, which measure the angle of
dip of beds penetrated by the well; deviation logs, which measure the degree
of deviation of the well bore from the vertical; and production-injection
logs.
82
-------
MT. SIMON
FORMATION
EAU CLAIRE FORMATION
o
o
o
3-
3
3
FIGURE 3-5a PORTION OF A LATEROLOG-GAMMA RAY-NEUTRON
LOG FROM A DEEP WELL IN NORTHERN ILLINOIS.
-------
LLl
O
eC
s:
o •
Oi OO
U- 1—1
o
CD -Z.
O "-i
O OC
OO UU
-------
2800
2900
3000
3100
O
CtL
CD O
O ^:
CL. h-
2: o:
LU O
.
O 3
h- CL.
CŁ. UJ
O UJ
0_ Q
UJ
a:
CD
-------
CO
(T)
CONCENTRATION
IN G/G »-
O o
O Ul
/ i —7 /
o o
o o
A. 40
(V
-------
The diameter of an uncased well is needed for quantitative use of many
of the geophysical logs and it is also useful in lithologic interpretation
and cement volume calculations. Data from dipmeter surveys assist in inter-
pretation of geologic structure. Deviation of boreholes from the vertical
is undesirable and periodic surveys are made during drilling to check bore-
hole orientation.
Production-injection logs are classified here as those logs that are
normally run through tubing or casing after the well is completed. Some of
these logs are the same as ones previously listed, but a number of specialized
logs are also used.
The principal uses of production-injection logs are to determine:
1. The physical condition of subsurface facilities
and the borehole
2. The location of production or injection zones
3. The quantity of fluid produced from or injected
into a particular zone
4. The results of wellbore stimulation treatment
Table 3-6 is a list of some production-injection logs that are most sig-
nificant in wastewater injection operations. The function of each of the logs
is also given. Examples of the use of a number of these logs are given in
Chapters 8 and 9. Further description of production-injection logs can be
found in the literature of the companies providing such logging services.'
Te_s_ti_rKj_p_f Injection Units and Confining Intervals
Examination of the records of many of the wastewater injection wells
that have been constructed up to the present time shows that, with few excep-
tions, the maximum amount of usable geologic and engineering information has
not been obtained during the testing of wastewater injection wells. This is
regrettable, because such tests provide the best basis for analyzing reservoir
conditions prior to injection , for predicting the long-term behavior of the
well and the reservoir, for detecting and understanding changes in well per-
formance that may occur during operation, and for analyzing the history of a
well from its records.
The methods for testing pumping or injection wells and the techniques
for analysis r,f test 'Jala are discussed in v.u-ierous textbooks and in hundreds
>f other puh li t.fi t. i oris concerni ng qrounflwa ter and pet role UP engineering.
-------
TABLE 3-6. PRODUCTION-INJECTION LOGS MOST USEFUL IN
LOGGING INJECTION WELLS AND THEIR FUNCTION
LOG
1 . Cement bond
2. Gamma ray
3. Neutron
FUNCTION
Determine extent and effectiveness of
casing cementing
Determine lithology
radioactive tracers
Determine lithology
and presence of
through casing
and porosity through
4. Borehole televiewer
5. Casing inspection
6. Flowmeter
7. High resolution
thermometer
8. Radioactive tracer
9. Fluid sampler
10. Casing collar
11. Fluid pressure
12. Casing caliper
casing
Provide an image of casing wall or well
bore
Locate corrosion or other casing damage
Locate zones of fluid entry or discharge
and measure contribution of each zone
to total injection or production
Locate zones of fluid entry including
zones behind casing
Determine travel paths of injected fluids
including behind casing
Recover a sample of well bore fluids
Locate casing collars for accurate
reference
Determine fluid pressure in borehole
at any depth
Locate casing damage
88
-------
Because the number of published articles and the scope of their content are
so extensive, only a few selected references are mentioned and a few examples
discussed here to establish the reasons for and methods of well testing.
A well can be tested by pumping from it or injecting into it. Measure-
ments of reservoir pressure or water level can be made during pumping or in-
jection or, alternatively, after pumping or injection has ceased and the re-
servoir is adjusting to its original condition. Furthermore, reservoir pres-
sure or water level can be measured in the principal well or in adjacent
observation wells. Any one of these approaches will yield much of the same
information; however, there are benefits and problems associated with either
injection or pumping tests that should be recognized.
The principal advantage of injection testing is that, since fluids are
to be injected during actual well operation, injection tests are more likely
to replicate operating conditions. Another advantage of injection tests is
that injection pumps are used on the ground surface, whereas pumps for pro-
duction testing will usually be submersible down-hole pumps that are more
time-consuming and expensive to use. Disadvantages of injection testing are
that, unless great care is exercised, the injection interval can be damaged
and the test results affected by reactions of the injected fluid with forma-
tion fluids or minerals. Differences between viscosity, density, or tempera-
ture of interstitial and injected fluids may also affect test results.
Production (pumping) tests avoid the potential for incompatibility be-
tween injected and interstitial fluids and formation minerals, but the prob-
lem of disposal of the produced formation water then arises. This water can
be reinjected, but chemical, physical, or biological changes often occur when
the water is brought to the surface that require the water to be treated be-
fore it is returned to the subsurface.
Drill-Stem Testing --
In the case of the usual deep and rather expensive wastewater injection
well, there will be no observation well and testing will be in the well it-
self. In the sequence of well construction and testing, the first type of
formation test that is likely to be made is the drill-stem test (DST). As
has previously been mentioned on Page 71, this test is analogous to a pumping
test of limited duration. Quantitative analysis is usually made using data
obtained during the period of pressure buildup (closed-in-period) following
the period in which the reservoir is allowed to flow.
Figure 3-9a is a schematic DST pressure record, with a description of
the sequence of events in a successful test with a sinqlo flow period, Figure
3-% is a schematic representation of a test in which no fluid was produced.
Conditions that may be encountered in a DST are widely variable and consid-
erable experience may be required in order to interpret an uir.iMi.il test.. 'he
(•(iripanins that provide tho testing services also provui*' ass i s *.anc. o in tost.
MI* erpret a 1, i on .
If .1 test is successful, pressure buildup ;iata h"r !h>- 'est are !ak"M
-------
t
0)
I
Base line
Time
Putting water cushion in drill pipe
Running in hole
Hydrostatic pressure (weight of mud column)
Squeeze created by setting packer
Opened tester, releasing pressure below packer
Flow period, test zone producing into drill pipe
Shut in pressure, tester closed immediately above packer
Equalizing hydrostatic pressure below packer
Released packer
FIGURE 3-9a.
NORMAL SEQUENCE OF EVENTS AS RECORDED ON THE CHART
DURING A SUCCESSFUL DRILL-STEM TEST (KIRKPATRICK, 1954).
90
-------
t
2
(L
Base line
Time
1. Running in hole
2. Hydrostatic pressure (weight of mud column)
3. Squeeze created by setting packer
4. Opened tester, releasing pressure below packer
5. Flow period, test zone open to atmosphere
6. Closed tester and equalizing hyd. pressure below packer
7. Pulled packer loose
8. Pulling out of hole
FIGURE 3-9b. SEQUENCE OF EVENTS AS RECORDED DURING A DRILL-STEM
TEST WHEN NO FLUIDS WERE PRODUCED (KIRKPATRICK, 1954).
-------
Figure 3-10, the graph at the top of the figure is the record of a DST with
dual flow and closed-in periods. The abbreviation ICIP signifies the initial
closed-in-period, FFP the final flow period, and FCIP, the final closed-in-
period. The data for both closed-in periods are plotted, as is shown in the
figure for the final period. The vertical axis of the plot is pressure, as
taken from the DST record, in psi. The horizontal axis is a plot of the log-
arithm of time during a flow period plus time during the closed-in period
(t + 0), divided by time during the shut in period (0). When this plot is
extrapolated to infinite time, (t + e)/0 = 1 (the logarithm of one is zero)
the intersection of the straight line, drawn through the data points, with the
vertical axis is interpreted as being the original reservoir pressure or sta-
tic formation pressure (Ps). The slope of the line (m) is the pressure dif-
ference for one log cycle (P - P-JQ). A series of calculations of formation
properties is then made.
The important properties that are routinely calculated are:
1. Static formation pressure
2. Transmissivity
3. Average effective permeability
4. Damage ratio
5. Radius of investigation.
The static formation pressure as determined from a successful test is
assumed to closely represent the original formation pressure at the elevation
of the pressure recording device. Transmissivity is average hydraulic con-
ductivity multiplied by the thickness of the test interval. The damage ratio
is an indication of the amount of plugging of pores in the formation during
drilling of the well. In addition to this routine information, drill-stem
tests may indicate the presence of and distance to nearby faults or facies
changes that act as barriers to flow or channels for rapid flow.
For detailed presentations of drill-stem test analysis, the reader
is referred to Gat!in (1960), Lynch (1962), Matthews and Russel (1967) and
Pirson (1963). Also, literature such as that by Murphy (undated) and Edwards
and Winn (1974) is readily available from companies that provide drill-stem
testing services.
As an example of DST analysis, data from one closed-in period obtained
during testing of the Mt. Simon Formation in a well in Ohio were selected.
Figure 3-11 is a plot of the pressure buildup data for that test. Extrapo-
lation of the data to the logarithm of (t + 0)/0 = 0 shows that the static
formation pressure (Ps) is 2750 psig. The gauge was at a depth of 5886 feet
in the well, so the fluid pressure gradient is 0.467 psi per foot of depth.
For the remaining calculations, the following additional values from the
test are needed (see any of the above references):
Pf = pressure at the end of the final flow period = 1061 psig
t = flow time = 62 min
92
-------
STATIC BOTTOM HOLE PRESSURE - P
SLOPE - m = P$ - P|Q
1180
LOG
t + 9
e
FIGURE 3-10.
EXAMPLE OF A PLOT OF DATA FROM A DRILL-STEM TEST WITH
DUAL CLOSED-1N PERIODS (MURPHY, UNDATED).
- 1160.
- II4O.
- 1100.
- 1080.
- 1060.
-------
a.
1
LU
cr
ID
UJ
o
2550
2600
2650
UJ 2700
CL
a.
2750
2800
I
I
O.I
0.2 0.3 0.4 0.5
LOGARITHM OF t+0/0
0.6
FIGURE 3-11. PLOT OF EXTRAPOLATED PRESSURE FROM
DRILL-STEM TEST DATA FROM AN INJECTION
WELL IN OHIO.
0.7
0.8
-------
171 = s ~ 10 = 63 psi Per
Q ~ average flow rate = 347 bbl/day
u = water viscosity = 1.065 centipoise
b = formation thickness = 105 ft.
Then,
T = transmissivity = 162.6 S. (mil 1idarcy- (3-1)
m ft/centipoise)
K = average permeability = .Li (millidarcys) (3-2)
b
0.183 (P - Pf)
DR = damage ratio = — (dimensionless) (3-3)
m
r = radius of investigation = (la)1/2 (feet) (3-4)
The transmissivity is computed to be 346 millidarcy-ft/centipoise, the
average permeability 3.5 millidarcys, the damage ratio 1.9, and the radius
of investigation 14.7 ft. These calculations reveal that the Mt. Simon For-
mation at this location has a very low capacity to accept injected fluids.
The capacity could theoretically be improved nearly 100 percent by removing
formation damage; reservoir stimulation by hydraulic fracturing would also
help, but the reservoir is not promising. No hydrologic boundaries were en-
countered within the radius of investigation, which was only about 15 feet.
Further well testing and core analysis results to confirm these findings are
discussed in the material that follows.
Injectivity Testing --
After an injection well has been drilled and possible injection inter-
vals identified by coring, by geophysical logging, and by drill stem testing,
injection tests will usually be run. For initial injection testing, truck-
mounted pumps are often rented and treated water used for injection rather
than wastewater. Frequently, more than one possible injection interval is
present and tests are performed on the intervals individually or on more than
one at a time. The common practice when performing an injection test is to
begin injection at a fraction of the final estimated rate, to inject at. this
rate for at least, several hours, then to repeat this process <\t incroasirml y
greater rates until a limiting rate or pressure is reached. Injection is
then stopped of the sequence in which a tost is performed, if iTcssmv,
time-, and flow data are accurately recorded, and if the rest, is run lorn;
i/'Mouqh, if, is t heoret ica 11 y possible to analy/e the test. However, simpler
tests tend to produce simpler and more reliable interpretation
iCitT'i'tf OP sore fii.ii] ore interval at ! ! " '" ire p.u'1 i<
-------
interpret and should be avoided if possible or alternately, both single and
multiple zone tests should be performed.
Figure 3-12 is a plot of the data from a constant-rate injectivity test
of the Mt. Simon Formation. The test was run at a rate of 75 gal/min for
about 25 hours. To obtain a value of transmissivity, Equation 3-1 can be
used, in which case, the result will be in millidarcy • ft/cp, as follows:
T = (162.6) (2571 .4 bbl/day) = 452 millidarcy • ft/centi poise
925 psi/log cycle
Alternately, a nonunitized equation can be used and the constant ad-
justed to give transmissivity in any desired set of units. Equation 3-1 in
nonunitized form is (Ferris, etal., 1962; Kruseman and De Ridder, 1970;
Lohman, 1972):
If, for example, it is desired to obtain the answer in ft2/day, then
the set-up would be:
T = (2.3) (14,437 ft3/day) = 1>33 ft2/day
(4ir) (1981 ft/log cycle)
This test was run on the same well for which the drill stem test analy-
sis was given, but the well bore was cleaned up and acidized before the in-
jectivity test, thus apparently leading to a slightly higher transmissivity
(452 millidarcy-ft/cp as compared with 346 mill idarcy ft/cp. ).
The injectivity test can further be used to determine the formation
storage coefficient from (Ferris, et. al . , 1962; Kruseman and DeRidder;
Lohman, 1972).
2.25 TtQ
S = - »- - [dimensionless] (3-6)
r
where
T = formation transmissivity
t0 - intercept of extrapolated test curve with time axis
r = effective radius of well bore
Equation 3-6 is nonunitized. Unitized for ft^/day, minutes, and
ft, it becomes:
S = _ _ 2_ [dimensionless] (3-7)
640 r2
96
-------
1500
CO 1000
Q_
UJ
cr
z>
CO
CO
LU
cr
o_
500
1 1 1 1 1—TT
THIS PORTION OF CURVE
NOT USABLE FOR ANALYSIS
/
\ / i i i i
psi
O.I
t. i 10
TIME - HOURS
FIGURE 3-12. PLOT OF PRESSURE BUILDUP DATA FROM AN
INACTIVITY TEST OF THE MT. SIMON FORMATION
IN OHIO.
-------
From Figure 3-12, t0 = 13.2 minutes and:
5 = 1.33 ft2/day (13.2 min) = Q 175
(640) (0.396 ft)2
As was discussed in Chapter 2, storage coefficient values for confined
aquifers are generally at least three orders of magnitude lower than the cal-
culated value of 0.175. It is believed that the unreasonable answer results
from the fact that the well was hydraulically fractured during an earlier in-
jection test, leading to a larger effective well radius. This is one of the
problems encountered in determining reservoir properties using a single well.
If an observation well existed, this difficulty would be eliminated. For this
well, a more reasonable value of the storage coefficient can be obtained by
using Equation 2-6 as was demonstrated in Chapter 2.
Another form of reservoir analysis that employs curve matching can also
be used. A detailed explanation of this procedure is given by Ferris, et. al.
(1962); Kruseman and DeRidder (1970) and Lohman (1972). Wilson et. al. (1973)
applied curve matching to data from an injection well at Mulberry, Florida.
The most interesting aspect of the example presented by Wilson et. al. (1973)
was that it appeared to show an observable amount of leakage through confining
beds. Witherspoon and Neuman (1972) discuss the theory and procedure for
analysis of leaky confining beds and give two field examples from gas storage
projects.
Predicting Effects of Injection
One purpose of obtaining all of the many types of geologic and engineer-
ing information that have previously been discussed here and in Chapter 2 is
to allow quantitative or semiquantitative estimates to be made of the effects
of injection on the subsurface environment. These calculated effects are then
used, along with all other information, as criteria in evaluating site suita-
bility and in developing operating and monitoring plans.
Wastewater Transport by Regional Flow --
A frequently asked question is, How far will injected fluids be trans-
ported from the injection site by the natural flow system? An estimate of
this can be made from Darcy's law (Equations 2-2, 2-3, 2-4).
Examples of such a calculation will be given for the Mt. Simon Formation
in Ohio and for the lower Floridan aquifer in Florida. Figure 3-13 shows
that, at the location of the Empire-Reeves injection well, the hydraulic grad-
ient is about 10 feet per mile toward the northwest. At this location, the
Mt. Simon Formation has an average permeability of 24 millidarcys (from a
drill stem test) and a porosity of 10.4 percent (Clifford, 1973).
Rearranging Darcy's law:
v = Q = Ł [L/T] (3-6)
98
-------
MICHIGAN^'
A—
r MILES.
/ .. ^ /•
^^ Altitude of potentiometric surface above sea level
(contour interval 200 feet, dashed where
' Inferred direction of flow
POTFNTIOMETRIC SURFACE OF THE MT.SIMON FORMATION IN OHIO AND VICICITY (CLIFFORD, 1973).
-------
where v = apparent velocity through entire area A.
Then,
= <
(3.7)
dL
where v = average velocity of flow through pores
<)> = porosity.
In order to use Equation 3-7, permeability must be converted into hy-
draulic conductivity in units consistent with the hydraulic gradient.
Twenty-four millidarcys is equivalent to 0.0585 ft/day or 21.36 ft/yr at
60° F. This value should be adjusted from 60° F to the formation temperature,
but is sufficiently accurate as it is for this estimate. Now, from Equation
3-7:
v = 21 . 36 ft/yr x 10 ft/mile
0.104
-0.39 ft/yr.
5,280 ft/mile
This evaluation shows that water in the Mt. Simon Formation in north-
central Ohio is moving northwest at a rate of 0.39 ft/yr. The source of the
hydraulic gradient and the fate of the moving water are not understood. Fur-
thermore, there are complications in the analysis itself, as pointed out by
Bond (1973). However, in spite of such uncertainties, it can be indisputably
concluded that water in the Mt. Simon Formation is moving at a negligible
rate at this location. This fact is sufficient for a practical analysis of
the monitoring needed at such a wastewater injection site.
As a further example, Figure 3-14 shows the potentiometric surface for
the lower Floridan aquifer in northwest Florida. There the hydraulic gradient
was about 1.33 ft/mile toward the southwest in the vicinity of the Monsanto
Company injection well prior to its operation. The permeability is about one
darcy and the porosity is estimated to be 10 percent (Goolsby, 1971 and 1972).
The velocity of natural flow in the lower Floridan aquifer is then estimated
to be
v = 890 ft/yr x 1.33 ft/mile = 2 24 ft/vr
0.10 5,280 ft/mile
This case is more easily interpreted than the previous one because it is
known that the source of hydraulic head lies to the north of the injection
well site and that the movement of water is to the south as shown in Figure
3-15. The velocity of flow, even in this case, is very low.
Pressure Effects of Injection --
Wastewater injected into subsurface reservoirs does not move into empty
voids; rather it displaces existing fluids, primarily saline water. The dis-
placement process requires exertion of some pressure, in excess of the natural
100
-------
86°30'
. 3l°00
EASTERN LIMIT-
BUCATUNNA CLAY
CONFINING BEDS
50°50'
f ^r
\2 MILES
Cootour shows oltitude of inferred __
potentiometr ic surfoce of the lower
limestone oDov« mean seo level, pre-
1963. Contour interval, 20 feet.
iOOO isochlor shows inferred chloride
concentration (milligrams per liter)
withm upper port of the lower limetlone
ou
Area where saline water from lower ^x
Fiondon oquifer moves upward and
mines with fresh water in upper Fioridon
aquifer under natural conditions
Fault,dashed where inferred
FIGURE 3-14. HYDROGEOLOGY OF THE LOWER FLORIDAN AQUIFER
IN NORTHWEST FLORIDA (GOOLSBY, 1972).
-------
•-ABOUT 75 MILES TO RECHARGE AREA
FIGURE 3-15.
SOUTH-NORTH REGIONAL HYDROGEOLOGIC CROSS
SECTION THROUGH THE MONSANTO COMPANY IN-
JECTION SITE IN NORTHWEST FLORIDA (FAULKNER
AND PASCALE, 1975).
102
-------
formation pressure. The pressure increase is greatest at the injection well
and decreases in approximately a logarithmic manner away from the well. The
amount of excess pressure required and the distance to which it extends de-
pend on the properties of the formation and the fluids, the amount of fluid
being injected, and the length of time that injection has been going on. The
pressure or head changes resulting from injection are added to the original
regional hydraulic gradients to obtain a new potentiometric surface map that
depicts the combined effects of regional flow and the local disturbances.
To compute the rate of pressure change in an injection interval, Darcy's
law must be combined with the continuity equation so that time and the com-
pressibility of the aquifer and aquifer fluids may be taken into account.
The appropriate partial differential equation and its derivation may be found
in most modern texts on hydrogeology and petroleum reservoir engineering,
along with numerous solutions.
The solution first formulated and still most widely used for predicting
the pressure effects of a well pumping from or injecting into an aquifer as-
sumes the following conditions (Ferris, et. al., 1962; Kruseman and DeRidder,
1970; Lohman, 1972):
1
The aquifer is, for practical purposes, infinite
in areal extent
2. The aquifer is homogeneous, isotropic, and of uniform
thickness over the area of influence
3. Natural flow in the aquifer is at a negligible rate
4. The aquifer is sufficiently confined so that flow
across confining beds is negligible
5. The well penetrates the entire thickness of the
aquifer
6. The well is small enough that storage in the well can
be neglected and water removed from or placed in
storage in the aquifer is discharged or taken in
instantaneously, with change in hydraulic head.
This is a formidable list of assumptions, which are obviously riot com-
pletely met in any real situation. However, if one reviews the characteris-
tics of many aquifers used for waste injection, water supply, and other pur-
poses, it can be concluded that for practical purposes they probaMv comply
sufficiently with the assumptions.
The equation that describes the response of such an j'juifer !.<,
-------
-
-------
b = reservoir thickness [ft]
t = time since injection began [hours]
c = reservoir compressibility
r = radial distance from well bore to point
of interest [ft]
= average reservoir porosity [decimal]
Two very important characteristics of the equations presented above are
that individual solutions can be superimposed, and that hydrologic boundaries
such as faults can be simulated by a properly located imaginary well. The
fact that solutions can be superimposed allows the effects of multiple wells
to be easily analyzed. Because the effect of boundaries is analogous to that
of properly located pumping or injection wells, the existence of boundaries
can be detected by observing aquifer response to injection or pumping or,
conversely, the effects of known or suspected boundaries can be estimated.
Equations 3-8, 3-9, and many other similar solutions that are available
for different assumed conditions are used to generate potentiometric surface
maps showing anticipated conditions at a selected time in the future. The
accuracy of the predicted effects is monitored as time passes and the pre-
dictions revised, if necessary, to better match actual aquifer performance.
Figure 3-16 shows the theoretical potentiometric surface map for the
lower Floridan aquifer in northwest Florida in 1974, after wastewater in-
jection had been in progress near Pensacola for about 11 years. The esti-
mated pressure effects of injection can be seen by comparing the contours
of the pre-injection potentiometric surface with the mid-1974 contours. The
predicted effects have been partially verified by observation wells, the lo-
cations of which are also given in the figure.
As an example of the development of such a theoretical potentiometric
surface map, one point in Figure 3-16 will be determined. The point will be
one at a radial distance of seven miles northeast of the injection well site,
which places it at a potential of about 80 feet on the pre-injection surface
and 180 feet on the 1974 surface. From Goolsby (1972) and Faulkner and
Pascale (1975) the following data were obtained or estimated:
Q - ?.49 x 106 gal/day = 3.33 x 105 ft3/day
T •••' 6,300 cjal/dayft - R-12 ft3/dayft
t 4,f)f)n days
r 7 i;:i ]<>s .'•;?>,%() ft
S ? x 1 ()"' f (I ii'ions ion 1 ess ) .
-------
INFERRED LINE OF EQUAL CHLORlDŁ CONCENTRATION W'THIN THE LOVfE* LIMESTONE,
MILLIGRAMS PER LITRE
UJD NORMAL ^AULT .N SuB
I 0 . DOWNTHRQWN SIDE I
'THROWN SI
IDE , -i
FIGURE 3-16.
REGIONAL HYDROGEOLOGIC MAP SHOWING EFFECTS OF
WASTE INJECTION BY MID-1974 ON THE POTENTIO-
METRIC SURFACE OF THE LOWER LIMESTONE OF THE
FLORIDAN AQUIFER (FAULKNER AND PASCALE, 1975).
106
-------
Therefore, from Equation 3-9, the head increase in 4,000 days 7 miles
northeast of the injection site is:
Ah = 2.30 x 3.33 x 1Q5 ft3/day
4^ x 842 ft3/day-ft
10 2.25 x 842 ft3/dayft x 4.000 days
°9 (36,960ft )2 x 2 x 10-4
= 72.39 log 27.74 = 104.5 ft.
The calculated increase of 104.5 feet compares well with the increase
of 100 feet shown in Figure 3-16, when the accuracy of the map scale is con-
sidered. As many points as desired can be calculated to produce the contour
map. Rather than calculating the pressure at a point (actually on a circle
with radius r) even head increments can be selected and the radii to them
calculated, which simplifies the contouring process.
The most common use of Equation 3-9 and similar equations is to predict
the pressure buildup that will occur during the planned lifetime of an injec-
tion well. This calculated pressure buildup is then compared with the allow-
able pressure buildup to determine if the injection will be feasible. As has
been explained, prior to drilling a well, the formation properties necessary
to perform this calculation are estimated. After the well has been drilled,
they are obtained from core analyses and well testing.
As an illustration, assume a site for which the limiting well head
pressure is 1,500 psi and the other conditions are:
Q = 1714.3 bbl/day (50 gpm)
LI = 1 centi poise
K - 50 millidarcys
b = 45 ft
t, = 8.76 x 10^ hours (10 years - projected lifetime of
the well)
c - 7.5 x 10"6 psi"1
r ().?9S ft. (3.5 inches -•• well mdiu'O
Us i r,(| [ Mud lion 3-9a :
-------
Ap = 062.6)(1714.3)(1)
(50)(45)
log
(50)(8.76 x
-3.23
1(T6)(.292)2
Ap = 1,292 psi
The calculation indicates that the anticipated pressure increase should
be less than the limiting amount after ten years of injection at 50 gpm.
The calculation is not sufficiently dependable to be relied upon to predict
the exact lifetime of a well, but it gives the best indication available as
to what should occur.
Multiple Wells-- As previously mentioned, estimating the combined pres-
sure effects of multiple wells is made easy by virtue of the principle of
superposition. It is only necessary to estimate the separate effects of two
or more wells at the point of interest, then to add them to obtain their
combined effect.
As an illustration of this, the effect of a second injection well lo-
cated 1,000 feet from the well analyzed above will be computed. Assuming
that the second well has the same characteristics as the first, the pressure
at either well after 10 years of operation of both wells would be:
Ap = 1,292 psi +
log
(50) (45)
(50)(8.76 x 104)
(0.15)0X7.5 x 10-6)(1,OOO)2
-3.23
J
Ap = 1,292 psi + 416 = 1,708 psi
The calculation indicates that it would probably not be possible to op-
erate the two wells at 50 gpm 1,000 feet apart for 10 years, since the injec-
tion pressure at each well would build up to 1,708 psi, which exceeds the
allowable 1,500 psi. Van Everdingen (1968) presents other examples of such
calculations for injection wells.
Hydrologic Discontinuities -- Another common situation is one in which
a barrier to flow, a fault or facies change, is present within the area of
influence of an injection well. Faults may also act as channels for escape
of fluid from the injection horizon.
In predicting aquifer response in the presence of such features, the
image-well concept is used. Assume the presence of a fault or lithologic
change that acts as an impermeable barrier, 500 feet in any direction from
the Mt. Simon Formation injection well that is discussed above. Then, ac-
cording to image-well theory, an imaginary injection well with all of the
same properties as the real injection well is placed 1,000 feet from the
real well, on the opposite side of the fault and on a line that passes
108
-------
through the real well and is perpendicular to the fault. Figure 3-17 shows
the potentiometric surface and flow lines that would develop in such a sit-
uation; the pressure effect of the barrier would be the same as that calcu-
lated above for an actual injection well 1,000 feet from the first well.
If the hydrologic discontinuity were a leaky fault rather than a sealed
one, the opposite effect would occur; the pressure at any time would be re-
duced as if a discharging well were present.
The equations and examples given are for the most basic hydrogeologic
circumstances, but many injection wells can be treated this way because these
are the conditions sought when choosing an injection site and receiving aqui-
fer. However, cases of virtually any complexity can be analyzed by use of
the appropriate solution to the basic flow equations; where analytical solu-
tions are not possible, numerical models can be developed. The limitations
to an analysis are usually pragmatic rather than theoretical—lack of data,
limitations of time and funds, or the fact that a simplified estimate is suf-
ficient for the circumstances.
Rate and Direction of Wastewater Movement --
As with pressure response to injection, the rate and direction of move-
ment of the injected fluid depend on the hydrogeology of the site; therefore,
the same factors previously listed require consideration. In addition, the
properties of the formation water and the injected wastewater assume major
importance.
Broad flow patterns in an aquifer with a significant existing potentio-
metric gradient can be deduced from a map of the regional potentiometric sur-
face with the effects of the injection system superimposed.
Figure 3-18 is a duplication of Figure 3-16, with flow lines added to
show how the flow directions of formation water and injected wastewater can
be deduced from the potentiometric surface map. The wastewater will never
actually travel as far northward as the map indicates, but displaced forma-
tion water will be forced in this direction, ahead cf the small cylinder of
wastewater that surrounds the well. The extent of this wastewater cylinder
will be discussed next.
A good estimate of the mi_n_imum distance of wastewater flow from an in-
jection well can be made by assuming that the wastewater will uniformly oc-
cupy an expanding cylinder with the well at the center. The equation for
this case is:
;
V
v ...... ~ r, -i
....... iL I
wher-:
r ~ radial distance of wastewater front t'rnr; well
V ' Of. • c'.riu 1 .•! t i vr volume of i n vi. ( >'•>'. ',•,'• r. t i>w,i t.er
-------
o
'// ^ -C. '
J/VŁ
%f r«*Łx-
>'V \
f-V-h—
S^->;
REAL
INJECTION
WELL
/y> ^
I ^
FIGURE 3-17. GENERALIZED FLOW NET SHOWING THE POTENTIAL LINES AND STREAM LINES IN THE VICINITY
OF AN INJECTION WELL NEAR AN IMPERMEABLE BOUNDARY (FERRIS ET. AL., 1962).
-------
FIGURE: 3-i«.
THEORETICAL POTENTIOMETRIC SURFACE OF LOWER LIMESTONE OF FLORIDAN
AQUIFER IN MID-1974, WITH FLOW LINES SHOWING THE DIRECTIONS OF
AQUIFER WATER AND WASTEWATER MOVEMENT. SOLID FLOW LINES SHOW THE
DIRECTION OF FLOW OF DIVERTED AQUIFER WATER, DASHED FLOW LINES
SHOW DIRECTION OF FLOW OP INJECTED WASTEWATER AND DISPLACED AQUIFER
WATER (MODIFIED AFTER FAULKNFR AND PASCALE, 1975).
-------
b = effective reservoir thickness
4> = average effective porosity.
For an injection well with the following characteristics:
Q = 100 gpm
t = 5 years
b = 1618 feet
<|> = 13.5 percent
r = , 35,128,99 3_ ft3.
V TT x 1618 ft x 0.135
= 226 ft
It is noted that effective reservoir thickness and average effective
porosity should be used. The effective reservoir thickness, for example, is
that part of the total reservoir that consists of sandstone (in the case of
a mixed sandstone-shale lithology.) The effective porosity has been previous-
ly defined as that part of the porosity in which the pores are interconnected.
In most situations the minimum radial distance of travel will be
exceeded, because of dispersion, density segregation, and channeling through
high permeability zones. Flow may also be in a preferred direction, rather
than radial, because of hydrologic discontinuities (e.g., faults), selective-
ly oriented permeability paths, or natural flow gradients.
An estimate of the influence of dispersion can be made with the follow-
ing equation:
r' - r + 2.3 \fOr~ • [L] (3-11)
where
r' = radial distance of travel with dispersion
D = dispersion coefficient; 3 ft for sandstone aquifers and
65 feet for limestone or dolomite aquifers.
Equation 3-11 is obtained by solving equation (10.6.65) of Bear (1972) for
the radial distance at which the injection front has a chemical concentration
of 0.2 percent of the injected fluid. The detailed development of dispersion
theory is presented by Bear (1972). The dispersion coefficients given are
high values for sandstone and limestone aquifers obtained from the literature.
112
-------
No actual dispersion coefficients are known to have been obtained for any
existing injection well.
Then for the above example, which is a sandstone:
r1 = 226 ft + 2.3 /3 ft x 226 ft
- 286 ft.
It is clear that, in this example, the distance of wastewater travel
from the well is negligible and could not possibly be of concern if actual
conditions comply even generally with those that were assumed. This conclu-
sion has been found to apply to many of the wells that have been constructed
to date. Since almost no attempts have been made to determine the actual
wastewater distribution around existing injection wells, there is little evi-
dence for comparison with theory. However, if such a calculation were in
error by several hundred percent, there would still be no cause for concern,
since the injection well, in this and many other cases, is tens of miles from
the nearest well penetrating the injection zone.
To proceed beyond the calculations that have been shown may not be
necessary or, in many cases, meaningful. However, it may be possible, if
necessary, to account for some of the additional complications that are men-
tioned. For example, Bear and Jacobs (1964), in one of a series of reports,
considered the flow of water from a groundwater recharge well in an aquifer
of uniform flow, when the densities and viscosities of the injected and inter-
stitial fluids are the same. Gelhar et. al. (1972) developed analytical
techniques for describing the mixing of injected and interstitial waters of
different densities. Kazman (1974) discussed the use of an aquifer model for
verification of complex waste flow patterns.
So far, the travel of the injected wastewater has been treated as
though it were an inert fluid whose constituents would not react with the
aquifer water or minerals, be affected by bacterial action, or decompose or
radioactively decay. If the wastewater is not inert, then changes in chemi-
cal composition with time and distance may also need to be considered.
Bredehoeft and Pinder (1972) discuss the methodology for a unified approach
to this type of problem. Robertson and Barraclough (1973) present an example
of a case in which radioactive decay, dispersion, and reversible sorption
were considered, and Intercomp Resource Development, and Engineering, Inc.
(1976) provides a description of and the computer program for a transient,
three-dimensional digital model that simulates wastewater movement, from an
injection well. The Intercom!) model accounts for density and viscosity vari-
ations resulting from temperafure and compositional changes and includes the
effects of hydrodynann'i. dispersion in producing uinipos i t iorial changes. How-
ever, no procedure exists at this time for simultaneously considering the
full ranqe of pro'.'••. j \> i 1 i I. j es that HMV he involved in was t.ewa t or
,"i(jve::;er)t. .
In
-------
well, nonuniform distribution of porosity and permeability will preclude
making accurate estimates in many cases. In general, wastewater flow in
unfractured sand or sandstone aquifers would be expected to more closely agree
with theory than flow in fractured reservoirs or in carbonate aquifers with
solution permeability. However, even in sand aquifers, flow can be expected
to be nonideal as shown by tests reported by Brown and Silvey (1973). Par-
ticularly great deviations from predictions may occur in limestone or dolomite
aquifers. Figure 3-19 is an example of this. The radial zones around Well
No. 1 show the predicted extent of waste travel using Equations 3-10 & 3-11.
The irregular boundary shows the probable actual extent of wastewater spread
as indicated by evidence from Wells 2 and 3. In this case, the wastewater
apparently traveled selectively in a single thin porous and permeable inter-
val rather than throughout the several zones indicated by testing results.
Accurate prediction of the rate and direction of movement in such a case may
well be technically infeasible even in the future because the amount of in-
formation needed will seldom, if ever, be available.
Hydraulic Fracturing --
Hydraulic fracturing may be deliberately accomplished to increase for-
mation receptivity or apparent permeability. It may occur during injection
testing or wastewater injection if the fracture initiation pressure is ex-
ceeded.
Regulatory policy may or may not allow short-term hydraulic fracturing
operations for well stimulation, but continuous injection at pressures above
the fracture point are prohibited by most, if not all, agencies. This is
because of the danger of damage to well facilities and because of the uncer-
tainty about where the fractures and injected fluids are going if fractures
continue to be extended. In order to produce and propagate a hydraulic frac-
ture that will achieve increased well receptivity, large amounts of pump
power, effective fluid loss control additives, and propping agents such as
sand, are desirable. Fractures may not propagate in normally permeable
rocks unless the fracture surfaces are continually sealed by the injected
fluid. In practice a fluid loss control agent that later breaks down and
becomes inoperative is employed to assist fracture propagation.
Figure 3-20 is a schematic diagram of bottom-hole pressure and surface
pressure versus time during hydraulic fracturing. Before injection begins,
the pressure is that of the formation fluid (p0) and the column of fluid in
the well bore. Pressure is increased until fracturing occurs; then, as fluid
continues to be pumped into the well, the pressure stabilizes at Pf, the
flowing pressure, during which the fractures continue to be extended. When
injection is ceased, and the well shut in, the pressure quickly stabilizes
to a constant value, the instantaneous shut-in pressure. This pressure is
considered to be equal to the least principal earth stress in the vicinity
of the well.
occur
In estimating the fluid pressure at which hydraulic fracturing will
, one of two conditions is usually assumed:
IK
-------
CALCULATED PRINCIPAL ZONE
OF WASTEWATER CONTAINMENT
INJECTION
WELL NO. 1
CALCULATED
DISPERSION
ZONE
PROBABLE ACTUAL EXTENT
OF WASTEWATER TRAVEL
• WELL NO. 2
• WELL NO. 3
SCALE: 1 in. = 1000 ft.
FIGURE
PREDICTED AND PROBABLE ACTUAL EXTENT OF
TRAVEL FOR A WELL COW! • TED IN A CARBONATT
-------
3000
4000
FORMATION
BREAKDOWN
w 3000
i
UJ
cc
CO
10
UJ
* 2000
C31
1000
SAND ADDED TO
FRAC FLUID
TT— INCRI
—\==
SAND LOAD
INCREASED
— DOWN HOLE PRESSURE
.— SURFACE PRESSURE
PUMPS OFF
FIGURE 3-20.
10 19
TIME - MINUTES
SCHEMATIC DIAGRAM OF PRESSURE
VERSUS TIME DURING HYDRAULIC
FRACTURING (KEHLE, 1964).
20
\
2!
-------
1. That the least principal stress is less than the
vertical lithostatic stress caused by the rock
column. In this case fractures are assumed to
be vertical .
2. That the vertical lithostatic stress is the least
principal stress. In this case fractures will be
horizontal.
In the first case, the minimum bottom-hole pressure required to ini-
tiate a hydraulic fracture can be estimated from (Hubbert & Willis, 1972):
Pl- = 5l±J^ (F/L2) (3-12)
where
P.J = fracture initiation pressure
Sz = total lithostatic stress
P - formation fluid pressure
The hydraulic fracturing gradient, that is, the injection pressure re-
quired per foot of depth to initiate hydraulic fractures, can be estimated
by entering representative unit values into Equation 3-12. The unit values
for Sz and p0 are, respectively, 1.0 and 0.46 psi/ft. This yields a p-j gra-
dient of 0.64 psi/ft as a minimum value for initiation of hydraulic fractures.
This situation implies a minimum lateral earth stress. As the lateral stress-
es increase, the bottom-hole fracture initiation pressure also increases up
to a limiting value of 1.0 psi/ft. Actually, fracture pressures may exceed
1.0 psi/ft when the rocks have significant tensile strength and no inherent
fractures that pass through the well bore.
In any particular case, injection tests can be run on the well to deter-
mine what the actual fracture pressure is. Operating injection pressures are
then held below the instantaneous shut-in pressure measured immediately fol-
lowing injection of fracture pressures. In the absence of any specific data,
arbitrary limitations of from 0.5 to 1.0 psi per foot of depth have been im-
posed on operating injection wells. Regional experience should be used as a
criterion in establishing an arbitrary limit, since regional tectonic condi-
tions and fluid pressure gradients dictate what a safe limit will be.
A recent scries of field experiments were performed in the Piceance
Basin of northwest Colorado to test the validity of the concepts discussed
above and to determine thr state of rock stress in that area (Wolff, ft. al.,
1975; Brcdehoeft, et.. a 1 . , 1976). The conclusions reached were consistent
with theory. The area was found to be tec tonic ally relaxed and vertical frac-
tures were qenerateci at about, two thirds of the overburden pressure, as would
bo predicted from [quat.inn 3-1?.
-------
Earthquake Triggering --
As a matter of background, it is widely, but not universally, accepted
that a series of earthquakes that began in the Denver area in 1962 was ini-
tiated by injection of wastewater into -a well at the Rocky Mountain Arsenal.
Since the association of seismic activity with wastewater injection at Den-
ver, apparently similar situations have been observed at Rangely, Colorado,
and Dale, New York. The former related to water injection for secondary re-
covery of oil and the latter to disposal of brine from solution mining of
salt. On the other hand, there are presently about 160 operating industrial
wastewater injection wells and tens of thousands of oil field brine disposal
wells that have apparently never caused any noticeable seismic disturbance,
so these three examples would have to be considered very rare.
It has been erroneously stated by many that the seismic events have
been stimulated by "lubrication" of a fault zone by injected fluids. What
has happened, if injection has been involved, is that the water pressure on
a fault surface has been increased, thus decreasing the friction on that
surface and allowing movement and consequent release of stored seismic en-
ergy.
Based on this interpretation of the mechanism of earthquake triggering
by fluid injection, some of the conditions that would have to exist in order
to have such earthquakes would be:
1. A fault with forces acting to cause movement of the blocks
on either side of the fault surface, but which are being
successfully resisted by frictional forces on the surface.
2. An injection well that is constructed close enough, verti-
cally and horizontally, to the fault so that the fluid
pressure changes caused by injection will be transmitted
to the fault plane.
3. Injection at a sufficiently great rate and for a suffi-
ciently long time to increase fluid pressure on the fault
plane to the point that frictional forces resisting move-
ment become less than the forces tending to cause movement.
At this time, movement will occur and stored seismic energy
will be released. That is, an earthquake will occur.
As has been discussed earlier in the section on state of stress, rela-
tively little is known about stress distribution in the earth's crust and
even less is known about stress distribution along fault systems. In the
absence of this information, only qualitative estimates of the probability
of earthquake stimulation can be made. In the great majority of cases the
potential for earthquake stimulation will be nonexistent or negligible be-
cause only very limited areas in the country are susceptible to earthquake
occurrence. The susceptible areas are delineated by records of earthquakes
that have occurred in the past and by tectonic maps that show geologic fea-
tures which are associated with belts of actual or potential earthquake
activity.
118
-------
In a case where subsurface stresses are known or are determined by hy-
draulic fracturing or other means, and where the location and orientation of
the fault plane are known, then a quantitative estimate of the pressure re-
quired to cause fault movement can be made. Raleigh (1972) provides an exam-
ple of such a calculation from the Rangely, Colorado, oil field.
-------
REFERENCES
CHAPTER 3
American Geological Institute. Glossary of Geology and Related Sciences.
2nd ed. Washington, D. C. '1976.
American Petroleum Institute. Recommended Practice for Core Analysis Pro-
cedure. API RP-40, Dallas, TX. 1960.
Bear, Jacob. Dynamics of Fluids in Porous Media. Elsevier Publishing Co.,
New York. 1972. 764 pp.
Bear, J., and Jacobs, M. The Movement of Injected Water Bodies in Confined
Aquifers. Underground Water Storage Study Report No. 13, Technion,
Haifa, Israel. 1964.
Bond, D. C. "Deduction of Flow Patterns in Variable-Density Aquifers from
Pressure and Water-level Observations." in Underground Waste Manage-
ment and Artificial Recharge. Jules Braunstein, ed. American Assoc.
Petroleum Geologists, Tulsa, Oklahoma. 1973. pp. 357-378.
Bredehoeft, J. D., et. al. "Hydraulic Fracturing to Determine the Regional
In Situ Stress Field, Piceance Basin. Colorado." Geol. Soc. of Amer.
Bull. Vol. 87. 1976. pp. 250-258.
Bredehoeft, J. D., and Pinder, G. F. "Application of Transport Equations to
Groundwater Systems." in Underground Waste Management and Environmen-
tal Implications. T. D. Cook, ed. Amer. Assoc. Petroleum Geologists
Memoir 18. 1972. pp. 191-199.
Brown, D. L., and Silvey, W. D. "Underground Storage and Retrieval of Fresh
Water from a Brackish-Water Aquifer." in Underground Waste Management
and Artificial Recharge. Jules Braunstein, ed, Amer. Assoc. of Pet-
roleum Geologists. Tulsa, Oklahoma. 1973. pp. 379-419.
Clifford, M. J. "Hydrodynamics of the Mount Simon Sandstone, Ohio and Adjoin-
ing Areas." in Underground Waste Management and Artificial Recharge.
Jules Braunstein, ed. American Assoc. of Petroleum Geologists, Tulsa,
Oklahoma. 1973. pp. 349-356.
Dobrin, M. B. Introduction to Geophysical Prospecting. McGraw-Hill Book
Company, New York. 1976.
120
-------
Edwards, A. G., and Winn, R. H. A Summary of Modern Tools and Techniques
Used in Drill Stem Testing. Presented at the dedication of the U. S.
East-West Trade Center, Vienna, Austria, June 14-17, 1973. Available
from Halliburton Services, Duncan, Oklahoma. 1974. 31 pp.
Faulkner, G. L., and Pascale, C. A. "Monitoring Regional Effects of High
Pressure Injection of Industrial Waste Water in a Limestone Aquifer."
Ground Water. Vol. 13, No. 2. 1975. pp. 197-208.
Ferris, J. G., et. al. Theory of Aquifer Tests. U. S. Geological Survey
Water Supply Paper 1536-E. 1962. 174 pp.
Gatlin, Carl. Petroleum Engineering Drilling and Well Completions. Prentice-
Hall, Inc., Englewood Cliffs, N. J. I960.
Gelhar, L. W., et. al. Density Induced Mixing in Confined Aquifers. U. S.
Environmental Protection Agency Water Pollution Control Research Series
Publication 16060 ELJ 03/72. 1972.
Haun, J. D., and LeRoy, L. W., eds. Subsurface Geology in Petroleum Explo-
ration, Colorado School of Mines, Golden, Colorado. 1958.
Hubbert, M. K., and Willis, D. G. "Mechanics of Hydraulic Fracturing."
in Underground Waste Management and Environmental Implications.
T. D. Cook, ed. Amer. Assoc. of Petroleum Geologists Memoir 18.
Tulsa, Oklahoma. 1972. 411 pp.
Jennings, H. Y., and Timur, A. "Significant Contributions in Formation
Evaluation and Well Testing." Journal Petroleum Technology. Vol. 25.
December, 1973. pp. 1432-1446.
Kazmann, Raphael. "Waste Surveillance in Subsurface Disposal Projects."
Gnaund. _W_a ter. Vol. 12, No. 6. 1974. pp. 418-426.
Kehle, R. 0. "The Determination of Tectonic Stresses through Analysis of
Hydraulic Well Fracturing." Journal Geophysical Research. Vol. 69,
No. 2. 1964. Dp. 259-273. '
Keys, W. S., and Brown, R. F. "Role of Borehole Geophysics in Underground
Waste Storage and Artificial Recharoe.'1 iri Underground Waste MaricUio-
I'lent and Artificial Recharge. Jules Braunstoin, ed. Aner. Assoc. o4
Petrol ei.ji;i Gen Yoq'is>V," Yl.il saT Oklahri"vi. 1^7':. ;-,;•. M7-191.
Kirkpatrick, C. V. "Format, ion Test inc." "'.'•." Pe " '.'"> I <'••.<'"' i ncri m — '' 1 !:;-'.
-------
Kruseman, G. P., and DeRidder, N. A. Analysis and Evaluation of Pumping Test
Data. International Institute for Land Reclamation and Improvement.
Bulletin 11. Wageningen, The Netherlands. 1970. 200 pp.
Lohman, S. H. Ground-Water Hydraulics. U. S. Geol. Survey Professional
Paper 708. 1972. 70 pp.
Lynch, E. J. Formation Evaluation. Harper and Rowe, New York, New York.
1962. 422 pp.
Matthews, C. S., and Russell, D. G. Pressure Buildup and Flow Tests in Wells.
American Institute of Mining, Met. Eng. Monograph, Vol. 1. 1967.
Murphy, W. C. 'The Interpretation and Calculation of Formation Characteristics
from Formation Test Data." Halliburton Services, Duncan, Oklahoma.
undated.
Pirson, S. J. Handbook of Well Log Analysis. Prentice-Hall Inc., Englewood
Cliffs, N. J. 1963. 326 pp.
Raleigh, C. B. "Earthquakes and Fluid Injection." in Underground Waste Man-
agement and Environmental Implications. T. D. Cook, ed. American
Assoc. of Petroleum Geologists Memoir 18. 1972. pp. 273-279.
Robertson, J. B., and Barraclough, J. T. "Radioactive-and-Chemical-Waste
Transport in Groundwater at National Reactor Testing Station, Idaho:
20-year Case History and Digital Model." in Underground Waste Manage-
ment and Artificial Recharge. Jules Braunstein, ed. Amer. Assoc.
Petroleum Geologists, Tulsa, Oklahoma. 1973. pp. 291-322.
Schlumberger Limited. Log Interpretation Volume I - Principles. Schlumber-
ger Limited, New York, New York. 1972.
Schlumberger Limited. Log Interpretation Charts. Schlumberger Limited,
New York, New York. 1972a.
Tucker, W. E., and Kidd R. E. Deep Well Disposal in Alabama. Geological
Survey of Alabama. Geological Survey of Alabama Bulletin 104. 1973.
Van Everdingen, A. F. "Fluid Mechanics of Deep-Well Disposals." in Sub-
surface Disposal in Geologic Basins - A Study of Reservoir Strata.
J. E. Galley, ed. American Assoc. Petroleum Geologists Memoir 10.
1968. pp. 32-42.
Wilson W. E., et. al. "Hydrologic Evaluation of Industrial-Waste Injection
at Mulberry, Florida." in Underground Waste Management and Artificial
Recharge. Jules Braunstein, ed. American Assoc. Petroleum Geologists,
Tulsa, Oklahoma. 1973. pp. 552-564.
Witherspoon, P. A., et. al. Interpretation of Aquifer Gas Storage Conditions
from Water Pumping Tests. American Gas Association, Inc., New York,
New York. 1967. 273 pp.
122
-------
Witherspoon, P. A., and Neuman, S. P. "Hydrodynamics of Fluid Injection."
in Underground Waste Management and Environmental Implications.
T. D. Cook, ed. American Assoc. Petroleum Geologists Memoir 18, Tulsa,
Oklahoma. 1972.
Wolff, R. G., et. al. "Stress Determination by Hydraulic Fracturing in Sub-
surface Waste Injection." American Water Works Association Journal.
Vol. 67. 1975. pp. 519-523.
-------
CHAPTER 4
CRITERIA FOR INJECTION WELL SITE EVALUATION
The geologic and hydrologic information necessary for evaluation of an
injection well site and the means of obtaining this information before and
during well construction have been discussed in the previous two chapters.
In this chapter, a procedure for using this information in determining the
suitability of a site for wastewater injection is outlined and the criteria
for a suitable site discussed.
As was indicated in Chapter 2, examination of a site for a wastewater
injection well begins at the regional level, then is narrowed to the vicinity
of the site, and finally focuses upon the immediate well location. Table 4-1
lists the factors important to regional and local site evaluation.
REGIONAL EVALUATION
Figure 4-1, presented by Van Everdingen and Freeze (1971), is a flow
diagram that shows a procedure for the regional evaluation of an injection
well site. The yes-no statements in the flow diagram are oversimplified;
but, in concept, the diagram represents the procedure that is followed,
whether consciously or not, in such evaluations.
Ideally suitable regions for subsurface wastewater injection should
satisfy the following criteria:
a. An extensive, thick sedimentary sequence should be
present, to provide opportunity for an adequate in-
jection interval and confining strata.
b. Geologic structure should be relatively simple, that is,
the region should be reasonably free of complex and ex-
tensive faulting and folding. Complex geologic structure
complicates prediction and monitoring of waste travel
and faults are possible avenues of wastewater escape.
c. Possible injection intervals should contain saline water
and should not be abundantly endowed with mineral re-
sources (oil, gas, coal, etc.), so that the potential
for degradation of natural resources is minimized.
124
-------
TABLE 4-1. FACTORS TO BE CONSIDERED FOR GEOLOGIC AND HYDROLOGIC
EVALUATION OF A SITE FOR SUBSURFACE WASTE INJECTION
Regional Geologic and Hydrologic Framework
Physiography and general geology; structure; stratigraphy;
ground water; mineral resources; seismicity; hydrodynamics
Local _Geo1_p_Ły _a_nd Geohydrology
A. Structural Geology
B. Geologic Description of Subsurface Rock Units
1. General rock types and characteristics
2. Description of injection horizons and confining
beds. Lithology; thickness and vertical and
lateral distribution; porosity (type and dis-
tribution as well as amount); permeability
(same as for porosity); reservoir temperature
and pressure; chemical characteristics of
reservoir fluids; formation breakdown or frac-
ture pressure; hydrodynamics.
3. Fresh water aquifers at the site and in the
vicinity. Depth; thickness; general character;
quality of contained water; amount of use and
potential for use.
4. Mineral resources and their occurrence at the
well site and in the immediate area. Oil and
qas (including past, present and possible future
development); coal; brines; other.
-------
EVALUATION OF
REGIONAL
STRATIGRAPHY
LARGE BASIN
THICK SEDIMENT
SEQUENCE
EVALUATION OF
REGIONAL
STRUCTURE
REGION FREE OF
MAJOR FAULTING
OR INTENSIVE
FOLDING
SLOW MOVEMENT
UNDER NATURAL
MORIZ GRADIENT
" YES
EVALUATION OF
REGIONAL
SEISMICITY
REGION FREE OF
SEISMIC ACTIVITY
REGIONAL GEOLOGICAL
MAPS, SUBSURFACE
DATA, ETC.
REGIONAL STRUCTURE
MAPS, SUBSURFACE
DATA, ETC
1
\;VALUA
REG
HYDROD1
• YES
riON OF /
NAMICS /
/ ^
S REGIONAL GROUND
SUBSURFACE DATA, ETC -^
EARTHQUAKE RECORDS,
SEISMICITY MAPS
1
' YES
ESTABLISH SUBDIVISION
i "POTENTIAL" REGIONS
2 "LIMITED
REGIONS
"CLOSED" REGIONS, NO SUBSURFACE
DISPOSAL ALLOWED
FIGURE 4-1. EVALUATION OF REGIONS FOR SUBSURFACE WASTEWATER
INJECTION (VAN EVERDINGEN AND FREEZE, 1971).
126
-------
d. Fluid flow in possible injection intervals should
be negligible or at low rates, and the region should
not be an area of ground water discharge for the
injection intervals being considered.
e. The region should preferably not be one of high seismic
risk, nor should it be a seismically active one. Earth-
quakes may damage injection facilities and, in seismi-
cally active area, injection may stimulate earthquakes.
The criteria used in a regional evaluation are perhaps best discussed
by application to an example. For this purpose, the entire conterminous
United States can be subjected to a superficial evaluation, which is useful
as a starting point for a more detailed analysis.
Synclinal sedimentary basins and the Atlantic and Gulf Coastal Plains
(Figure 4-2) are particularly favorable sites for waste-injection wells be-
cause they contain relatively thick sequences of salt-water-bearing sedimen-
tary rocks and because commonly the subsurface geology of these basins is
relatively well known. Galley (1968) discussed general aspects of geologic
basin studies as related to deep-well disposal of radioactive waste.
During the early 1960's a series of reports concerning the suitability
of selected basins for radioactive waste disposal was prepared for the Atomic
Energy Commission by the U. S. Geological Survey. These reports included
ones by Repenning (1961) on the Central Valley of California, Sandberg (1962)
on the Williston basin, Beikman (1962) on the Powder River basin, MacLachlan
(1964) on the Anadarko basin, LeGrand (1962) on the Atlantic and Gulf Coastal
Plain, and Colton (1961) on the Appalachian basin; Love and Hoover (1960)
briefly summarized the geology of many sedimentary basins in the United
States.
In addition to the USGS basin reports, members of a subcommittee of the
Research Committee of the American Association of Petroleum Geologists pre-
pared reports for the AEC on portions of the Appalachian basin, the Michigan
basin, the Salina basin, the Denver basin, and the San Juan basin (Galley,
1968-a).
In spite of these extensive investigations, only one well, the Anaconda
Company well near Grants, New Mexico (West, 1972), is known to have been used
for liquid radioactive waste injection. However, the listed reports are also
of general use for evaluation of sites for wells ir.joct. inq non-radioact i ve
was tes.
Just, as najor synclinal basins are qcolooicdllv
was tewa Lor injection, other areas :'''ay be general 1 y '.jrif.
sod iv.pnt a ry-rnc k cover is thi'i or absent. E x tons i'.•'•• ar
i::'i)en:;cati 1 e igneous-intrusive and "ietamornh ic roci •. .ire
face are shown ir f icjure 'l-l-'. With the possible (:>;L (.-;'•',
these areas (-an he el iri na ' ed fro'" cons I'd^ra t. inn for v.-a
exposure o1' iiinon'js and :pv* a!snnihi r rnrk;, in the Ar:\j
f'':i:,n ' < i ':•, , i lann, :-}i;rl 0/,>r-l 'j; ii"'1, '!'!•• >• • ;-.; •'-, ,.ji"'' ,'.
-------
co
EXTENSIVE AREAS WHERE VOLCANIC
SEQUENCES ARE EXPOSED AT SURFACE
• INDUSTRIAL-WASTE INJECTION SYSTEMS (FEBRUARY.I966)
* GEOLOGIC DETAIL NOT SHO'
FIGURE 4-2. GEOLOGIC FEATURES SIGNIFICANT IN DEEP WASTE-INJECTION
WELL-SITE EVALUATION, AND LOCATIONS OF INDUSTRIAL-WASTE
INJECTION SYSTEMS (WARNER, 1968).
-------
Shield, and other such exposures are perhaps not extensive, but they are sig-
nificant because the sedimentary sequence thins toward them and the salinity
of the formation waters decreases toward the outcrops around the exposures.
Regions shown in Figure 4-2 where a thick volcanic sequence lies at
the surface generally are not suitable for waste-injection wells. Although
volcanic rocks have fissures, fractures, and interbedded gravel that will
accept injected fluids, they generally contain fresh water.
The immense and geologically complex Basin and Range Province is a
series of narrow basins and intervening, structurally positive ranges. Some
of the basins might provide waste-injection sites, but their geology is most-
ly unknown and the cost of obtaining sufficient information to insure safe
construction of injection wells could be high.
The geology of the West Coast is relatively complex. Small Tertiary
sedimentary basins in southern California yield large quantities of oil and
gas, and probably are geologically satisfactory sites for waste-injection
wells. There are similar basins along the coast of northern California,
Oregon, and Washington, but little is known about their geology.
Areas not underlain by major basins or prominent geologic features may
be generally satisfactory for waste injection if they are underlain by a suf-
ficient thickness of sedimentary rocks that contain saline water, and if po-
tential injection zones are sealed from fresh-water-bearing strata by imper-
meable confining beds.
A number of discussions have appeared in recent years, describing the
feasibility of industrial wastewater injection in individual states and one
region, including those by Bergstrom (1968) on Illinois, Kreidler (1968) on
New York, Newton (1970) on Oregon, Rudd (1972) on Pennsylvania, Clifford
(1972) on Ohio, Tucker and Kidd (1973) on Alabama, and the Ohio River Valley
Water Sanitation Commission (1973) on the Ohio River Valley region. The
study of the Ohio River Valley will be briefly reviewed as an example of a
regional assessment. Figures 4-3 through 4-9 are from the ORSANCO (1973)
study.
Example of a Regional Evaluation
Stratigraphy --
The thickness of sedimentary rocks throughout the area can be estimated
by examination of Figure 4-3, which is a structure contour map on the top of
the Precambrian basement surface. The thickness of sedimentary rock at any
point, is obtained by subtracting the elevation of the Precambrian surface
froir the elevation of the ground surface. Since till of the Preca!r:brian sur-
face elevations in the nap are below sea level, and elevation'", are negative,
they are actual!1/ ad. It is clear that t'H-re is more than 3,'Ksi toft of
scd i I'icn ta r y rocks ovcoijf in Virginia, where Pret ar:br i an rocks are exi'osoc! ,11
-------
FIGURE A
Map of the Ohio River Basin and vicinity
OF FEET. DATUM SEA LEVEL.
OUTCROP OF BASEMENT ROCKS- PRIMARILY IGNEOUS
AND METAMORPH1C ROCKS OF PRECAMBRIAN AGE
FIGURE 4-3.
(OHIO RIVER VALLEY
WATER SANITATION COM-
MISSION, 1973).
130
-------
LEGEND
t.VA.P 1 A fJ O
EARLY t^A. I I oy O i
Ml SSI SS\ PP I AN -
VAN IAN
SEQUENCE
DhVOU I
SHALE
bfcQ U E M C
S I L U R I /\ N
Ot VON IAN
SA-QU C NCt
ORDOV I C I A.N
SHALE
SEQUENCE
(.AM, BR I A.N
QRnoVIClAN
S( Q VJ t N f ,1
L. !-r
i:
i- * •> s i o i) i N (.. i i j / / / y
-------
CD
d
73
m
i
01
o
rr:
»—i
o
70
CO
IV)
-------
FIGURE 7
Mop of Iht Ohio Riv0r Bonn and vicinity thawing
Aouil
Data modili.d Fram F.lh. 1965
EXPIANATION
riGURF. 4-6. (OHIO RIVLR VALLEY
WAT!'!-; SANITATION COM-
MISSION, 10/3).
-------
FIGURE B
Map of the Ohio River Basin and
Data modified frorri published oil and gas field maps.
LITTLE OR NO OIL AND <5A5 FIELD DEVELOPMENT
FIGURE 4-7.
(OHIO RIVER VALLEY
WATER SANITATION COM-
MISSION, 1973).
134
-------
-f-
FIGURf 14
Map of the Ohio River basin
and vicinity showing the
degree ot seismic risk as
projected from earthquake
history and geologic considerations.
From Algermissen. 1969
LEGEND
j^g MAJOR DAMAGE FROM
BB EARTHQUAKES MAY OCCUR
^H MODERATE DAMAGE FROM
" EARTHQUAKES MAY OCCUR
- MINOR DAMAGE FROM
- EARTHQUAKES MAY OCCUR
FIGURf. <";-'••:. HAP Of" IMF Oil 10 RUTR
BASH AMD VICINITY
SiiD'AlNCi THL DEGRU 0!
S: ISMir RISK AS PRO-
.M'c:; i) FROM rARTi!'',!i.;Af
-------
FIGURE 9
MAP OF THE OHIO RIVER BASIN AND VICINITY
NDICATING THE RELATIVE FEASIBILITY OF DISPOSAL
AND THE ROCKS MOST UKELY TO PROVIDE A
SATISFACTORY DISPOSAL ZONE.
EXPLANATION
DEEP WELL DISPOSAL IS MOST LIKELY TO BE FEASIBLE IN
I PENNSYLVANIAN, MISSI5SIPPIAN OR OLDER ROCKS
H DEVONIAN, SILURIAN, OR OLDER ROCKS
TSL ORDOVICIAN OR OLDER SOCKS
DEEP WELL DISPOSAL IS OF LIMITED FEASIBILITY
BECAUSE OF LACK OF AVAILABLE DISPOSAL
HORIZONS OR COMPLEX OEOLOGIC STRUCTURE
METAMORPHIC AND IGNEOUS CRYSTALLINE ROCKS
NO POSSIBILITY OF DEEP WELL DISPOSAL
EXISTING INJECTION WELLS
FIGURE 4-9. MAP OF THE OHIO RIVER BASIN AND VICINITY
INDICATING THE RELATIVE FEASIBILITY OF
DISPOSAL AND THE ROCKS MOST LIKELY TO PRO-
VIDE A SATISFACTORY DISPOSAL ZONE.
136
-------
to near the top of the sedimentary sequence and are from Cambrian to Pennsyl-
vanian in age as shown in Figure 4-4.
Structural Geology --
Major structural geologic features of the Ohio Valley and surrounding
areas are shown in Figure 4-5. Major synclinal basins or downwarps of the
crust are the Appalachian basin and the Illinois basin. Small portions of
the Michigan basin and the Mississippi embayment are also within the Ohio
Valley. The Cincinnati arch and its continuations, the Kankakee and Findlay
arches to the north and the Nashville dome to the south are major uplifts
separating the basins. The outcrop of crystalline rocks that forms the core
of the Appalachian Mountain ranges (Blue Ridge province) represents a major
anticlinal fold that bounds the Appalachian basin on the southeast. Each of
the major folds has many smaller ones superimposed upon it. The southeastern
portion of the Appalachian basin is, in particular, complexly deformed by
many smaller folds as indicated in Figure 4-5. A zone of very intense and
complex folding, faulting and fracturing ranging from a few miles up to about
80 miles in width borders the northeast-southwest trending crystalline core
of the Appalachian Mountains from the Alabama-Georgia border north into Can-
ada. Other areas of relatively intense rock deformation are the faulted and
fractured Rough Creek, Kentucky River, and associated fault zones.
Ground Water and Other Resources --
The principal chemical measurement used to distinguish between reser-
voirs suitable for wastewater injection and those containing waters that must
be protected is total dissolved solids content. So far, there is no complete
agreement on which ground waters should be protected, but perhaps this is
best because exceptional cases occur and a rigid restriction makes it diffi-
cult to accommodate them. The most restrictive policy known is used in Illi-
nois and Texas, where ground water containing less than 10,000 mg/liter is
protected. On the other hand, injection is presently being allowed into an
aquifer with water containing less than 1,000 mg/liter in at least one in-
stance and Florida uses a limiting value of 1,500 mg/liter for aquifers to
be protected.
In Figure 4-6 it shows the approximate depth to aquifers containing
greater than 1,000 ppm of dissolved solids in the Ohio Valley and adjacent.
areas. This map was used because it is the only one available showing the
dissolved solids content of ground waters in the Ohio Valley region. It
gives a very broad indication of the depth range to which surface casing
must extend in order to close off aquifers containing potable water. It
also shows that there are no sal ine-water-beari no, aquifers to bo used for
disposal in portions of the eastern Ohio Valley. If waters containinq r:ore
than 1,000 ppm of dissolved solids are considered fresh, which will probably
he the case, then larqer areas of the, Ohio Valley would be unsuited for
underground disposal and the depth to the fresh water-saline water interface
would be extended.
-------
are often physically well suited for waste injection. In Figure 4-7 the rel-
ative extent of oil and gas field development in the Ohio Valley area is
shown. Extensive development of oil and gas resources does not necessarily
preclude injection disposal. However, the potential for such disposal will,
within certain areas, be greatly limited because of oil and gas development.
For example, in the Lima-Indiana oil field area shown in Figure 4-7, nearly
75,000 wells were drilled during the late 1800's and early 1900's. These
oil wells are now abandoned and many of their locations are unknown.
Because of the inadequate plugging practices used at the time when the
Lima-Indiana field was abandoned, it is not now possible to contemplate in-
jection into the Trenton Limestone or any of the horizons above the Trenton
in that area. Injection into the deeper Mt. Simon Formation, which lies
well below the Trenton, is still possible as is illustrated by the Sohio
Petroleum Company injection well at Lima, Ohio. It is not practical to list
all of the situations similar to this that exist in the Ohio Valley. How-
ever, matters such as this must be considered individually at the time when
underground disposal is actually contemplated at a specific location.
Earthquake Occurrence and Triggering —
The past history of earthquake activity in an area must be considered
because an earthquake might potentially damage injection well facilities or
alter geohydrologic conditions. In addition, because of the possibility that
injection may induce earth tremors, the susceptibility of an area to such
induced seismic activity should be examined.
Within and near the Ohio Valley Region, two localities stand out as
having been affected by significant earthquakes during recorded time. Three
of the most intense earthquakes that have been recorded in this country were
centered near New Madrid, Missouri, and occurred in December, 1811, and Jan-
uary and February, 1812. All three of these earthquakes were of greater in-
tensity than any that have occurred in California, including the 1906 San
Francisco earthquake.
A second area in the Ohio Valley where relatively intense earthquakes
have been recorded is in western New York. Here earthquakes with intensities
of 8 were recorded in 1929 and 1944. These two earthquakes were centered
near Attica and Massena, New York, respectively. Changes in groundwater con-
ditions reportedly occurred in 1929. A less intense 1966 earthquake was also
centered near Attica, New York. Recent data depicting the degree of seismic
risk throughout the Ohio Valley are shown in Figure 4-8. These data agree
with the above discussion and indicate that there is a possibility of major
earthquake damage in the extreme southeast and northeast portions of the
Ohio Valley and of moderate to minor damage elsewhere in the area. These
areas are also ones where the initiation of earthquakes would be most likely.
In fact, it has been reported that seismic activity has been stimulated in
the Dale, New York, area by injection of brine from solution mining.
138
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Summary --
The geology and groundwater hydrology of the Ohio Valley have been
broadly considered in view of the potential for subsurface waste injection
in the area. Implications of the previous discussion are partly summarized
in Figure 4-9. Here is indicated the relative feasibility of deep-well dis-
posal as constrained by the thickness of sedimentary rocks, geologic struc-
ture, and the presence of saline-water-bearing aquifers. Areas underlain
only by metamorphic and igneous crystalline rocks provide virtually no poten-
tial for subsurface disposal of liquid waste. Areas where subsurface waste
injection is indicated as being of limited feasibility are those where:
No aquifers containing more than 1,000 mg/1 of dissolved
solids are available, as indicated in Figure 4-6;
The saline-water-bearing sedimentary sequence is less
than 1,500 feet thick;
Structural geologic conditions are considered sufficiently
complex to cause great uncertainty about subsurface hydro-
logy.
Within the areas where the above limitations do not apply, feasibility
of waste injection is shown as being most likely in one or more of the strati-
graphic sequences indicated in Figure 4-9. In Zone I, disposal feasibility
is shown as being most likely in Pennsylvanian, Mississippian, or older rocks.
There is at least 1,500 to 2,000 feet of Mississippian-Pennsylvanian sedimen-
tary rock present containing water with 1,000 mg/1 or more of dissolved solids
in Zone I. In Zone II, there is at least 1,500 to 2,000 feet of Silurian-Dev-
onian rock present containing saline water and in Zone III there is at least
1,500 to 2,000 feet of Ordovician and Cambrian sedimentary rock present con-
taining saline water.
While Figure 4-9 offers broad geographic guidelines, it cannot be used
to specify where subsurface injection may or may not be permitted. For exam-
ple, in constructing the map, aquifers with water containing more than 1,000
mg/1 were considered as having waste-disposal potential, whereas, at least
in Illinois and New York, the dissolved solids content would have to be
greater (10,000 mg/1 and 2,000 mg/1, respectively) before an aquifer could
be considered for waste injection. Some other limitations of the map are:
It. does not consider the presence of unplugged abandoned
wells or the locations of mineral resources.
The fact that 1,500 feet or more of saline water-bearing
sedimentary rock is present does not assure that a suitable
porous and permeable injection horizon or <) suitable cnn-
finim; interval will he present.
Areas of relatively ni!]h seismic risk a>'e
for use bet riuso PVti 1 u.,11 i rn of" the h(i:vir.:!
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damage and earthquake mitigation are considered to
be related to specific well location and depth.
This illustrates the procedure used in a regional evaluation. It is
not considered desirable to try to establish specific numerical criteria that
can be used everywhere, because of the obvious difficulty of doing so for
even one individual area. Also, it should be realized that only rarely, if
ever, will any such regional study allow more than a preliminary evaluation
of the suitability of a specific site, unless the site is in a totally unac-
ceptable location, in which case no further evaluation is needed. If a site
is located in a generally acceptable area, then a detailed examination of the
local geology and subsurface hydrology is required prior to construction of
a test well, and a reevaluation made after the well has been constructed and
tested.
LOCAL SITE EVALUATION
Factors for consideration in local site evaluation are listed in Table
4-1. Figure 4-10 is, similarly to Figure 4-1, a flow diagram that illus-
trates the local site evaluation procedure. As with Figure 4-1, it should
not be considered a rigid format.
Very briefly, a potential disposal site and injection interval should
have the following characteristics:
a. Injection interval sufficiently thick, with
adequate porosity and permeability to accept
waste at the proposed injection rate without
necessitating excessive injection pressures.
b. Injection interval of large enough areal extent
so that injection pressure is minimized and so
that injected waste will not reach discharge
areas.
c. Injection interval preferably "homogeneous"
(without high-permeability lenses or streaks),
to prevent extensive fingering of the waste-
vs-formation water contact, which would make
adequate modeling and monitoring of waste
movement extremely difficult or impossible.
d. Overlying and underlying strata (confining
beds) sufficiently thick and impermeable, to
confine waste to the injection interval .
e. Structural geologic conditions generally
simple, that is a site reasonably free of
complex faulting and folding.
140
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DETAILED GEOLOGICAL
MAPS. SUBSURFACE
DATA, ETC
OlSPOSAL FORMATION
OF ADEQU:
EXTENT, PERMEABILITY
AND POROSlT
LOW F^ u 'D P RESSuRE ,
si.0* HOP iz MOVE MENT ,
DOWNWARD OR ZERO
VERTICAL GRAO1 E*T .
NO jNPLuGGEC O.D
Wt^L 5 NEABB*
•-: 11 Cl IT; ()r FORMATIONS A'i!) A»i AS !'')H SUHSUl^ACf
H !'J;ViSTf'iA[. 'JASTT. (VAN i V! !•':'! N1 ,i N AN'H I |.!i i /!
-------
f. Site is an area of minor to moderate earth-
quake damage and low seismic activity so that
the hazard of earthquake damage or triggering
of seismic events is minimized.
g. Slow lateral movement of fluid in the injection
interval, under natural conditions, to prevent
rapid movement of waste away from the injection
site, possibly to a discharge area.
h. Formation-fluid pressure normal or low so that
excessive fluid pressure is not needed for in-
jection.
i. Formation temperature normal or low so that the
rates of undesirable reactions are minimized,
including corrosion.
j. Wastewater compatible with formation fluids and
minerals or can be made compatible by treatment,
emplacement of a buffer zone, or other means.
k. Formation water in the disposal formation of no
apparent economic value, i. e. not potable, un-
fit for industrial or agricultural use, and not
containing minerals in economically recoverable
quantities.
1. Injection interval adequately separated from
potable water zones, both horizontally and
vertically.
m. Waste injection not to endanger present or future
use of mineral resources (coal, oil, gas, brine,
others).
n. Waste injection not to affect existing or
planned gas-storage or freshwater-storage pro-
jects.
o. No unplugged or improperly abandoned wells pene-
trating the disposal formation in the vicinity
of the disposal site, which could lead to con-
tamination of other resources.
As can be seen from Figure 4-10 and the above list, the same general
geologic and engineering properties that are examined at the regional level
are also examined at the local level, but in more detail. As has been shown,
in a regional examination, an objective is to identify an adequate thickness
of rocks within which to find an injection interval and confining strata.
At the local level, the objective is to identify specific potential injec-
tion intervals and confining strata and to predict their performance under
142
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projected operating conditions. This same rationale applies to other cri-
teria, such as structural geology, hydrodynamics, subsurface resources, etc.
The procedure for local evaluation of an injection well site should
first provide for documentation of the results of analysis of items a-o above
prior to drilling of a well, then if the site is judged suitable for construc-
tion and testing of a well, each item should be reanalyzed as information is
obtained during drilling and testing. The final decision as to whether or
not wastewater injection is feasible is based on the subsurface data that
have been acquired during drilling and testing and which have then been used
to project the response of the subsurface geologic and hydrologic system to
sustained injection.
No specific numerical criteria are suggested in this chapter to be em-
ployed in site evaluation, but numerous quantitative examples are given in
Chapter 3, as are the means of acquiring data for site evaluation prior to
and during well construction.
Example of Local Site Evaluation
To illustrate local site evaluation procedures, the characteristics
listed above will be applied to the siting of a well for injection of low
level radioactive wastes at the Midwest Fuel Recovery Plant (MFRP) of the
General Electric Company near Morris, Illinois. The plant is not operative
and never has been; but, if it ever should operate, subsurface injection
would be one alternative for handling of the tritium-bearing wastes that
result from reprocessing of nuclear fuel (Belter, 1972). This particular
example was chosen principally because of the ready availability of the
needed information and because the site lies within the region evaluated in
the first part of this chapter. The characteristics a-o, listed above, will
be addressed in sequence.
In addition to the reference sources that are cited, information con-
cerning the superficial geology and shallow subsurface geology was obtained
from the "Safety Analysis Report, Midwest Fuel Recovery Plant, Morris, Illi-
nois," NEDO-10178, December, 1970.
Geographic Description of the Site --
The plant is located in Section 35 of T.34N., R.8E., and Section 2 of
T.33N., R.8E. It is about one mile southwest of the confluence of the Kan-
kakee, Des Plaines, and Illinois Rivers and is near the eastern border of
Grundy County. It is immediately adjacent to the Dresden Power Station, a
nuclear power reactor operated by Commonwealth Edison Co. The qround ele-
vation at the site is approximately 500 ft. and the topography is relatively
level. The area is predominantly aqricultural .
Stra * i fjra|)hy and Reservoir ProuerVies -
S.irface and shallow sjbsur''t!( r investigations al Uu: site have shown
..) Mver c'~ soil ran<;in•.•'••
-------
of the Maquoketa Group of Ordovician age. Beneath the Maquoketa, the strati -
graphic sequence is as shown in Figure 2-1. The estimated thickness of each
of the subsurface units is shown below:
STRATIGRAPHIC COLUMN
MIDWEST FUEL RECOVERY PLANT
GRUNDY COUNTY, ILLINOIS
SYSTEM ROCK UNIT
Pennsylvanian Pottsville (?)
Ordovician Maquoketa
Galena
Platteville
Glenwood
St. Peter
Shakopee
New Richmond
Oneota
Cambrian Trempeleau
Franconia
Ironton
Galesville
Eau Claire
PREDOMINANT
ROCK TYPE
Sandstone "|
Limestone &
Shale i
Dolomite
Dolomite and
Limestone
Sandstone
Sandstone
Dolomite
Sandstone and
Dolomite
Dolomite
Dolomite
Sandstone
Sandstone
Sandstone
Shale
ESTIMATED
THICKNESS (FEET)
Variable, 80 feet
total at one drill
site.
230
115
5 - 30
165
70 - 90
45 - 55
210
200
130
120
55+
400+
Confining Unit
Basal Sandstone
(Mt. Simon Aquifer)
Sandstone
2,500+
As discussed in Chapter 2, the most suitable injection interval in
northeastern Illinois is the basal sandstone or Mt. Simon aquifer. Figure 2-3
shows that the basal sandstone should have a thickness of just over 2,500
feet at the site. Figure 2-3 also shows that the basal sandstone is widely
144
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distributed and that it maintains a thickness of over 500 feet throughout
most of Illinois and Indiana.
The basal sandstone consists principally of fine-to coarse-grained
sandstone. It is commonly poorly sorted and contains conglomeritic zones.
Cross-bedding is often visible in cores. It ranges in color from clear in
quartzose portions to pink in the arkosic intervals. It may be only slightly
cemented and friable, or silica cemented and very hard. Although the forma-
tion is primarily sandstone, shale beds are often present, particularly near
the top or base. These beds are from a few inches to more than 50 feet
thick. The basal sandstone rests unconformably on Precambrian age igneous
or metamorphic rocks. In northeastern Illinois, the basal sandstone is
overlain directly by the Eau Claire Formation, which is dominantly composed
of shale.
The Illinois Water Survey (1973) examined the reservoir properties
of the basal sandstone with reference to disposal of brine from desalination
plants. Locations from which drill cores were available for analysis are
shown in Figure 4-11. Average porosity of the cores was found to be 11 to
13 percent. This agrees well with Figure 2-11, which shows that the average
porosity of the basal sandstone at the site should be about 13 percent. The
Illinois Water Survey (1973) found that the geometric mean value of core
permeabilities from northeastern Illinois locations ranged from about 4 to
over 40 mi 11idarcys (Figure 4-12), Field tests from the same area yielded
a range of 12.3 to 1040 millidarcys. Because of geologic and engineering
considerations, the Illinois Water Survey (1973) concluded that it is
reasonable to place more weight on the field tests than on the core analyses.
One procedure for evaluating the reservoir response to injection is to
assume that the permeability might be any value within the range obtained
from the field tests. This procedure will yield a range of pressure buildup
estimates. If the site would be acceptable under even the most pessimistic
assumption, then construction of a well would appear to be a good risk. If
it would not be suitable even under an optimistic assumption, then the site
would appear to be a poor risk. The same reasoning can be applied to selection
of a compressibility or storage coefficient. No values of compressibility
are available for the entire thickness of the basal sandstone, so a value
must be estimated. If the compressibility of water alone is considered,
c - 3 x 10 psi~''. A more reasonable value that would account for
the compressibility of the aquifer skeleton also would be 7.5 x 10"^
psi ~1 •
Because the basal sandstone is underlain by Precambrian age crystal-
line rock, downward migration of injected waslewa'er is not possible. Fig-
re ?-:> shows that the basal sandstone is overlain directly by about 400 feet
Figure ?-t> indicates that the Cau Claire
' one a t. that lor. at ion ,
i iinf i n i nc purposes • f-0n>
-------
AMERICAN
1—POTASH CO.
DuPace
MFRP
site
f1T. SIMON GAS
STORAGE PROJECTS
WASTE DISPOSAL
'WELL
WASTE DISPOSAL
TEST HOLE
FIGURE 4-11.
LOCATIONS OF DRILL CORES FROM MT. SIMON AQUIFER OR BASAL
SANDSTONE (ILLINOIS WATER SURVEY, 1973).
146
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i r
i i r
TROY GROVE
Ł 40
I 30
5
201—
10
ANCONA
GARFIELD
EXPLANATION
A WASTE DISPOSAL
• GAS STORAGE
LAKE
BLOOMINGTON
HUDSON
HERSCHER
AMERICAN
POTASH CO.
LEXINGTON
& LSTEEL
CORP."
A
PONTIAC
MAHOMET
J L_
8 10 12 14 16 18 20 22 24 26 28
AVERAGE DEPTH BELOW MEAN SEA LEVEL (100 ft)
FIGURE 4-12. HORIZONTAL PERMEABILITIES DETERMINED FOR
DRILL CORES FROM THE MT. SIMON AQUIFER OR
BASAL SANDSTONE (ILLINOIS WATER SURVEY, 1973)
30
32
34 36
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Structural Geology --
Major structural features in Illinois are shown in Figure 4-13. The
plant is located northeast of the Illinois basin and is on the eastern flank
of the La Salle anticlinal belt. The regional dip on the top of the basal
sandstone is about 25 feet per mile or about one-fourth of a degree south-
east, at that location. Dip on the Precambrian basement is about 100 feet
per mile or about one degree to the southeast. The only significant struc-
tural feature in the immediate vicinity is the Sandwich fault zone. The
Sandwich fault zone extends for 150 miles from near Oregon southeastward to
a location south of Joliet. It is generally downthrown on the northeastern
side, with a maximum displacement of more than 900 feet near its center
(McGinnis, et. al., 1976).
The structure is termed the Sandwich fault zone, rather than the Sand-
wich fault, because it appears to be compound rather than a single fault.
As can be seen in Figure 4-13, the plant site is about seven miles south of
the Sandwich Fault Zone. According to Buschback (1964), near the Grundy-Will
County border, in the vicinity of the plant site, the structure is downthrown
on the south side and has a maximum displacement of slightly over 100 feet.
Detailed investigations at the Midwest Fuel Reprocessing Plant site
resulted in the location of a nortHwest trending fault that crosses the
southwest corner of the site. The fault is downthrown on the southwest side
and has a vertical displacement of about 40 feet. Such a fault would not be
of concern unless it were to act as a flow path for liquid escape through the
confining beds. This is not likely, but could not be entirely precluded,
since leakage of gas from a storage field in northern Illinois has occurred
and escape along faults has been advanced as one possible mechanism (Hallden,
1961) for the leakage. As another example, Bond (1972) has suggested the
possibility of natural fluid flow from the basal sandstone upward along
faults into the overlying Galesville Sandstone in northwestern Indiana.
Initiation and times of movement on the Sandwich fault zone are as
follows: Movement did not occur until after the Silurian Period and was
perhaps coincidental with movement along the La Salle anticline. Major
movements along the La Salle anticline occurred during early Pennsylvanian
time, with lesser uplift after the Pennsylvanian period (Payne, 1939; Clegg,
1965; Atherton, 1971). No movement is believed to have occurred along the
Sandwich fault zone for millions of years and faults in the zone and those
associated with it are classified as inactive.
Earthquake Occurrence and Triggering --
Figure 4-8 shows the Midwest Fuel Recovery Plant site is an area of
minor earthquake damage risk. No special precautions should be needed to
protect an injection well from earthquake damage. Because faults in the
Sandwich fault zone and vicinity are inactive, the triggering of earthquakes
by fluid injection at the site would seem unlikely. However, the presence
of the Sandwich fault zone would suggest that this factor should be consider-
ed in some detail in reaching a decision as to the suitability of the site
for wastewater injection.
148
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UVf ', '
s ^ *J \"i *.1ipp' f T»bO«n'k»r<
MFRP
site
MA.'IOR ruoi.or.ic sIRUCT;W[s IN
(Me HINDIS, 11. Al. . , !('7f,;
-------
Hydrodynamics and Reservoir Conditions --
The recharge area for the basal sandstone or Mt. Simon aquifer is south-
eastern Wisconsin, where precipitation percolates downward through glacial
drift and, where present, through a thin cover of overlying bedrock units into
the basal sandstone (Illinois Water Survey, 1973). Southward into Illinois,
the overlying Eau Claire Formation becomes more shaly and dolomitic (Figure 2-6)
and ground water in the basal sandstone occurs under artesian conditions. Move-
ment of ground water in the basal sandstone in northeastern Illinois is be-
lieved by Bond (1972) to be southeastward toward Indiana. Flow in northwestern
Indiana may then be upward through faults into the Ironton-Galesville aquifer,
which lies above the Eau Claire confining interval (Bond, 1972). Bond (1972)
calculated the rate of movement in the basal sandstone to be a few inches per
year. That is consistent with the flow rate in the basal sandstone in Ohio
that was calculated in Chapter 3. Hydrodynamic circumstances are, therefore,
apparently favorable, since water in the basal sandstone is confined and is
moving laterally at the proposed site at a rate so low that geologic time
would be required for it to reach a discharge point.
Bond's (1972) data also show that reservoir pressures in the basal sand-
stone in northern Illinois are in the range that would be anticipated and that
no abnormal pressure conditions appear to exist other than minor effects caused
by local withdrawal of water or injection of gas through wells for storage pur-
poses. At the site, the dissolved solids content of water in the upper part
of the basal sandstone is probably less than 10,000 mg/1 whereas the TDS con-
tent of water in the lower part would be expected to be much greater (Illinois
Water Survey, 1973; Ohio River Valley Water Sanitation Commission, 1976).
Therefore, no single hydrostatic pressure gradient is applicable from top to
bottom of the basal sandstone. The gradient as measured to the top of the bas-
al sandstone at the site of interest is probably only slightly greater than
that of fresh water, which is 0.433 psi/ft whereas at the bottom of the gra-
dient is probably 0.44 to 0.45 psi/ft.
Geothermal gradients are also in the normal range. The geothermal gra-
dient map for Illinois (U. S. Geological Survey-American Association of Pet-
roleum Geologists, 1976) shows a gradient of 1.4° to 1.6°F. per 100 feet of
depth for northeastern Illinois. The Illinois Water Survey (1973) reports
that the temperature of the upper portion of the Mt. Simon at a gas storage
project in La Salle County ranged from 75° to 81°F. Using a geothermal gra-
dient of 1.5° per 100 feet of depth, an average ambient temperature of 55°F.,
and a depth of 1,850 feet to the top of the basal sandstone, the temperature
at the top of the basal sandstone would be estimated to be:
55°F. + 1.5(18.5) - 83°F.
The temperature at the bottom of the basal sandstone, at a depth of
about 4,350 feet would be estimated to be:
550F. + 1.5(43.5) - 120°F.
Compatibility of Wastewater with Formation Water and Minerals --
Trevorrow et. al . (1975) discussed in some detail the probable nature of
the low-level wastewater that will result from the commercial reprocessing of
spent fuels from light water nuclear reactors. The conclusion reached is
that the normal low-level waste will probably be virtually pure water with
the exception of nitric acid, which would be present at an estimated concen-
150
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tration of 600 mg/1. Tritium is the contaminant of concern and does not
change the density or viscosity of water significantly.
Because of the absence of dissolved ions, reaction with formation water
would not be a problem. Since the wastewater will be acidic (pH - 2), unless
it is neutralized, reaction with carbonate minerals in the injection interval
will occur. The injection interval is a sandstone; therefore reaction would
be limited to the carbonate fraction in the sandstone, which is a small
amount in the Mt. Simon aquifer in northeastern Illinois. Probably the only
reaction that might be significant would be between the wastewater and clay
minerals in the sandstone. This possibility would have to be examined by
testing of cores from the basal sandstone.
Subsurface Resources --
Ground Water—A generalized description of aquifers in northeastern
Illinois is given in Table 4-2. Glacial drift and Silurian rocks are not
present at the Midwest Fuel Reprocessing Plant site. Ground water was en-
countered during shallow subsurface studies at four to five feet below the
ground surface in weathered and fractured bedrock of the Maquoketa Group.
The piezometric level in the shallowest confined aquifer, the Galena-Platte-
ville Dolomite, was estimated to be about 84 feet below the ground surface
in one test hole. Aquifers down to and including the Ironton and Galesville
sandstones probably contain usable water at the plant site. According to
Bergstrom (1968, Fig. 3) water in the Ironton-Galesville Sandstone should
contain water with a content of less than 1,500 mg/1 total dissolved solids.
The upper portion of the basal sandstone (Mt. Simon aquifer) should contain
more than 1,500 but less than 10,000 mg/1 total dissolved solids. (Bergstrom,
1968; Ohio River Valley Water Sanitation Commission, 1976). The salinity of
water in the basal sandstone should increase with depth and should be much
greater than 10,000 mg/1 total dissolved solids. The lower basal sandstone
in the Jones and Laugh!in Steel Company well in Putnam County, west of the
Midwest Fuel Reprocessing Plant site, contained water with about 62,000 mg/1
total dissolved solids.
Water with less than 10,000 nig/I total dissolved solids is protected
under present regulatory policy in Illinois. Therefore, it is possible that
wastewater injection would be precluded at the Midwest Fuel Reprocessing
Plant site. The actual chem'stry of water in the basal sandstone would have
to be confirmed by drilling and a regulatory decision then made whether or
not to allow wastewater injection. Because the Eau Claire confining inter-
val is about 400 feet thick ana is composed principally of siltstone and
shale, upward vertical leakage of injected waste would not be expected to
endanger shallower aquifers, unless local fault in-; provided a
tical novel1"'!!t of water fro;", the ;>ac,al sandstone-
tratine; t.ho hasal sandstone is
thrt-i. i ] (•>:•, north of the- incint
i ?>;(.'• 1 OIM ' i;"i t'.'s*' and h.r. be-on
at. a d'S'1'': s! i ,"'67 for* in 'hi
>'
-------
TABLE 4-2. GENERALIZED DESCRIPTION OF
AQUIFERS IN NORTHEASTERN ILLINOIS
GEOLOGIC UNITS
THICKNESS
(ft)
WATER-YIELDING PROPERTIES
Glacial drift 0-400+
Silurian dolomite 0-400+
Maquoketa shale 0-250
Galena-Platteville 150-350
dolomite*
Glenwood-St. Peter 75-650
sandstone*
Prairie Du Chien, 45-790
Trempealeau dolomite, and
Franconia Formations*
Ironton-Galesville 103-275
sandstone*
Eau Claire shale 235-450
Eau Claire and 2000±
Mt. Simon sandstones
Yields of wells variable, some well
yields greater than 1000 gpm
Yields of wells variable, some well
yields greater than 1000 gpm
Generally not water-yielding, acts
as barrier between shallow and
deep aquifers
Water-yielding where not capped by
shales
Estimated transmissivity 15 percent
that of Cambrian-Ordovician aquifer
Estimated transrnissi vity 35 percent
that of Cambrian-Ordovician aquifer
Estimated transmissivity 50 percent
that of Cambrian-Ordovician aquifer
Generally not water-yielding, acts
as barrier between Ironton-Gales-
ville and Mt. Simon
Moderate amounts of water, permea-
bility between that of Glenwood-
St. Peter and Ironton-Galesville,
water quality problem with depth
*Col1 actively referred to as Cambrian-Ordovician aquifer
152
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Oil and Gas--No significant petroleum resources are known to exist in
northeastern Illinois.
Coal--Coal is present in Pennsylvanian age strata in the vicinity of
the Midwest Fuel Reprocessing Plant, but not on the plant site itself. Coal
beds are very near the surface in this area and would not be affected by
wastewater injection into the basal sandstone.
Gas Storage — Natural gas is stored in anticlinal structures at several
location in northern Illinois (Buschbach and Bond, 1973). Since no potential
storage structure has been defined at the plant site or in the immediate vi-
cinity, wastewater injection would not be expected to conflict with gas stor-
age-
Summary --
After cursory examination of the characteristics listed as important in
a local site evaluation, it appears that the Midwest Fuel Recovery Plant site
favorably meets most criteria, but may not meet some. First, the basal sand-
stone, which is the likely injection interval, probably contains water with
less than 10,000 mg/1 dissolved solids in the upper part. Under present
Illinois policy and practice it would not be permissible to inject into such
a reservoir. Second, the plant site is within about seven miles of the Sand-
wich fault zone and one fault has been identified at the plant site. The lo-
cal faulting could provide a pathway for vertical escape of fluid from the
injection interval, and the possibility that increased subsurface fluid pres-
sure could activate movement on faults in the area cannot be entirely pre-
cluded. If serious interest were to exist in constructing and operating an
injection well at the site, these problem areas would need to receive criti-
cal examination.
-------
REFERENCES
CHAPTER 4
Atherton, Elwood. "Tectonic Development of the Eastern Interior Region of
the United States." Bond, D. C., Chairman, Background Materials for
Symposium on Future Petroleum Potential of NFS Region 9 (Illinois
Basin, Cincinnati Arch, and northern part of Mississippi Embayment):
Illinois State Geological Survey Illinois Petroleum 96. 1971 pp. 29-
43.
Beikman, H. M. Geology of the Powder River Basin, Wyoming and Montana, with
Reference to Subsurface Disposal of Radioactive Wastes. U. S. Geolo-
gical Survey Trace Elements Inv. Report 823 (open file). 1962.
Belter, W. G. "Deep Disposal Systems for Radioactive Wastes." in Underground
Waste Management and Environmental Implications. T. D. Cook, ed. Am.
Assoc. of Petroleum Geologists Memoir 18, Tulsa, Oklahoma. 1972.
pp. 341-354.
Bergstrom, R. E. Feasibility of Subsurface Disposal of Industrial Wastes
in Illinois: Illinois State Geological Survey Circular 426. 1968.
Bond, D. C. Hydrodynamics in Deep Aquifers in the Illinois Basin: Illinois
State Geological Survey Circular 470. 1972.
Buschbach, T. C. Cambrian and Ordovician Strata of Northeastern Illinois.
Illinois Geological Survey Report of Investigations 218. 1964. 90 pp.
Buschbach, T. C., and Bond, D. C. Underground Storage of Natural Gas in
111inois. Illinois Geological Survey Petroleum 101. 1974. 71 pp.
Clegg, K. E. "The La Salle Anticlinal Belt and Adjacent Structures in East-
Central Illinois." Transactions of the Illinois Academy of Science.
v. 58, no. 2. p. 82-94; Illinois State Geological Survey Reprint
1965-H. 1965. 13 pp.
Clifford, M. J. Feasibility of Deep-Well Injection of Industrial Wastes In
Ohio. Ohio State University. Unpublished M. S. thesis. 1972.
Col ton, G. W. Geologic Summary of the Appalachian Basin, with Reference to
the Subsurface Disposal of Radioactive Waste Solutions. U. S. Dept.
of the Interior Geological Survey. TEI-791. June, 1961.
154
-------
Galley, J. E. "Economic and Industrial Potential of Geologic Basins and
Reservoir Strata." in Subsurface Disposal in Geologic Basins -
A Study of Reservoir_Strata. J. E. Galley, ed. Amer. Assoc. of
Petroleum Geologists, Inc., Tulsa, Oklahoma. 1968. pp. 1-10.
Galley, J. E., ed. Subsurface Disposal in Geologic Basins - A Study of
Reservoir Strata. A. A. P. G. Memoir 10. Amer. Assoc. Petroleum
Geologists, Inc., Tulsa, Oklahoma. 1968a.
Hallden, 0. S. "Underground Natural Gas Storage (Herscher Dome)." in
Ground Water Contamination. U. S. Dept. of Health, Education and
Welfare, Technical Report W61-5. Cincinnati, Ohio. 1961. pp. 110-
115.
Hidalgo, R. V. and Woodfork, L. D. "EDP as an Aid for Decision Making in
Subsurface Injection of Liquid Wastes." in Underground Waste Management
and Artificial Recharge. J. Braunstein, ed. Amer. Assoc. Petroleum
Geologists, Inc., Tulsa, Oklahoma. 1973. pp. 133.
Illinois Water Survey. Feasibility Study on Desalting Brackish Water from
the Mt. Simon Aquifer in Northeastern Illinois. Urbana, Illinois.
1973. 120 pp.
Kreidler, W. L. "Preliminary Study of Underground Disposal of Industrial
Liquid Waste in New York State." in Subsurface Disposal of Industrial
Wastes, published and distributed by the Interstate Oil Compact Com-
mission. Oklahoma City, Oklahoma. 1968.
Le Grand, H. E. Geology and Ground-Water Hydrojogy of the Atlantic and Gulf
Coastal Plain as Related to Disposal of Radioactive Wastes. U. S.
Geological Survey Trace Elements Inv. Report 805. 1962.
Love J. D. and Hoover, L. A_ jj_mm_ary_ of the Geology of Sedimentary Basins of
JLhJL JJjlil^L States, with Reference jto_the_ Pi sposaf of Radioacti ve
Wastes . U. S. Geological Survey Trace Elements Inv. Report 768 (open
file). 1960.
MacLachlan, M. E. The_ Anada_r_kp Basin (_pf_Pjrts of Oklahoma , Texa_s_, Kan_sas,
a_n_d_ Colo_radc) . U. S. Geological Survey Trace Elements Inv. Report
~"
McGinnis, L. D., et. al. The Gravity Fi_eld__and Tectonics of Illinois, Illi-
nois State Geological Survey Circular 494. 1976. 28 pp
Newton, V. C., Jr. Gepjpc|ic Consideration in the Disposal of Chemical arid
Radioactive Wastes. Oregon Dept. of Geology and Mineral Industries,
PorYlVnd, Oregon". 1970.
Ohio R i VI-M- Valley Water San i t, ii t. ion Commission. Under'iround Injection ot
Wastuwater in the Ohio Valley Region. ORSANCO." Cincinnati, Ohio.
1973. .......... "
-------
Ohio River Valley Water Sanitation Commission. Evaluation of the Ohio Valley
Region Basal Sandstone as a Wastewater Injection Interval. Cincinnati,
Ohio. July, 1976.
Payne, J. N. "The Age of the La Salle Anticline." Transactions of the Illi-
nois State Academy of Sciences, v. 32, no. 2. 1939. pp. 171-173.
Repenning, C. A. Geologic Summary of the Central Valley of California, with
Reference to Disposal of Liquid Radioactive Waste. U. S. Geological
Survey Trace Elements Inv. Report 769 (open file). 1961.
Rudd, N. Subsurface Liquid Waste Disposal and Its Feasibility in Pennsyl-
vania. Pennsylvania Geological Survey, Fourth Series. Environmental
Geology Report 3. Harrisburg, Pennsylvania. 1972.
Sandberg, C. A. Geology of the Williston Basin, North Dakota, Montana, and
South Dakota, with Reference to Subsurface Disposal of Radioactive
Wastes. U. S. Geological Survey Report TEI-809. 1962.
Trevorrow, L. E., Warner, D. L., and Steindler, M. J. Considerations Affect-
ing Deep-Well Disposal of Tritium-Bearing Low-Level Aqueous Waste from
Nuclear Fuel Reprocessing Plants, ANL-76-76, Argonne National Labora-
tory, Argonne, Illinois. March, 1977. 190 pp.
Tucker, W. E. and Kidd, R. E. Deep Well Disposal in Alabama. Alabama
Geological Survey Bulletin 104. University of Alabama. 1973.
U. S. Geological Survey - American Association of Petroleum Geologists.
Geothermal Gradient Map of North America. U. S. Geological Survey
Branch of Distribution, Arlington, Virginia. 1976.
Van Everdingen, R. 0. and Freeze, R. A. Subsurface Disposal of Waste in
Canada. Inland Waters Branch, Department of the Environment. Tech.
Bulletin. No. 49. Ottawa, Canada. 1971. 64 pp.
Warner, D. L. "Subsurface Disposal of Liquid Industrial Wastes by Deep-
Well Injection." in Subsurface Disposal In Geologic Basins - A Study
of Reservoir Strata. J. E. Galley, ed. A. A. P. G. Memoir 10, Am.
Assoc. Petroleum Geologists, Inc., Tulsa, Oklahoma. 1968. pp. 11.
West, S. W. Disposal of Uranium - Mill Effluent by Well Injection in the
Grants Area, Valencia County, New Mexico. U. S. Geological Survey
Professional Paper 386-D. 1972.
156
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CHAPTER 5
WASTEWATER CHARACTERISTICS
Table 5-1 lists the characteristics of the untreated wastewater that
must be considered in evaluating its suitability for disposal by subsurface
injection. Preliminary examination of these factors will show, in general,
if the effluent is such that more detailed appraisal is warranted. During
a detailed study, it is attempted to define all of the design and operational
problems related to the wastewater and to provide for these by plant process
control, wastewater pre-treatment, design modification, and operational pro-
cedure.
As pointed out by Wright (undated), it is not usually necessary for
injection purposes to know the exact chemical composition of a wastewater,
because empirical tests can be run to determine the reactivity and stability
of a waste. However, this information should be obtained so that the envi-
ronmental effect of the injected fluid can be assessed.
In this chapter, the items in Table 5-1 are discussed individually with
regard to their basic nature and, more importantly, with regard to their ef-
fect on injection practice.
GLUME
One of the most constraining limitations in managing a wastewater by
subsurface injection is the volume that can be safely injected for the de-
sired length of time. This is because the intake rate or life of an indivi-
dual well is limited by the properties of the injection interval, which can-
not be changed much. The variable limiting the injection rate or well life
can be the injection pressure required to dispose of the produced waste.
Injection pressure is a limiting factor because excessive pressure causes
hydraulic fracturing and possible consequent damage to confining strata.
In addition, the pressure capacity of inject ion-well pumps, tubing, and casing
i s 1i n i ted.
The initial pressure required to inject waste at a specified rate5 and
the rate at which injection pressure increases wit.h time can be calculated,
as is discussed in Chapter 3, if the i^vsical properties of the aquifer and
waste ..ire known. The intake rate of 'nr.t .vast.e-i njec lion wells now in use
is less than •-00 op::, (Warner find Orcut.'.. I-1."'; I!. S. Environmental Protection
Agency, 197-1;, but i|;'!,ih- rares can he hi";r->r i r; ;..-)rt ic. u i arl y fa vorti f.< 1 o <. ir-
(- U'T. t. •''.'}(..!."•• . ['if ;;;.>( •»'.-! t i n <; 1 i f e of a n i', • ec'. i CIM w • 1 1 nay .-! 1 <:, o \":>"' r'ei-.i?e:.l to
'he volume of ir, iectr-.l v;a s! e. l.^ecciuse Vie '.i'starue- in'ccted waste (.at; he
-------
TABLE 5-1. FACTORS TO BE CONSIDERED IN EVALUATING THE SUITABILITY
OF UNTREATED WASTES FOR DEEP-WELL DISPOSAL
A. Volume
B. Physical Characteristics
1. Density
2. Viscosity
3. Temperature
4. Suspended solids content
5. Gas content
C. Chemical Characteristics
1. Dissolved constituents
2. pH
3. Chemical stability
4. Reactivity
a. With system components
b. With formation waters
c. With formation minerals
5. Toxicity
D. Biological Characteristics
158
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allowed to spread laterally may be restricted by law or by other considera-
tions. The storage volume in the vicinity of an injection well can be com-
puted very simply, but dispersion, absorption, and chemical reaction compli-
cate the calculation of the distribution of injected waste. This topic is
also discussed in greater detail in Chapter 3.
PHYSICAL CHARACTERISTICS
Density
The density of the injected wastewater contributes to the injection
pressure by virtue of the pressure developed by the column of water in the
well. In some wells, this pressure alone is sufficient to drive the waste
into the formation and no pump is needed. In all wel""s, this pressure com-
ponent must be included in calculations. Once the wastewater is in the for-
mation, its density affects the manner in which it flows away from the well.
Low density wastes tend to float on saline formation waters and flow up-dip,
while dense waters sink and tend to flow down-dip.
Various industrial wastewaters have densities that span the full range
of possibilities for an aqueous waste. For example, the dissolved solids
content of low-level radioactive wastewater from the fuel-reprocessing cycle
is so small that it is essentially distilled water with a density of 1.0
gm/cm^ (Trevorrow, et. al., 1977). On the other hand, saturated brines from
a desalination plant may have densities as high as 1.15 gm/cm^ and steel
plant waste densities as high as 1.2 gm/cm^ (Warner, 1972; U. S. Environmen-
tal Protection Agency, 1974).
Viscosity
As previously discussed in the section on subsurface fluids, viscosity
is the ability of a fluid to resist flow, and is one of the fundamental prop-
erties that determines the rate of flow of a fluid through a porous medium.
Furthermore, in wastewater injection, the ratio of the viscosity of the in-
jected water to the formation water (the mobility ratio) has an important ef-
fect on the amount of mixing that occurs between the injected and intersti-
tial water during travel through the injection reservoir. Mixing is greatly
increased when the viscosity of the injected fluid is less than that of the
interstitial fluid.
As with density, the viscosity of industrial wastes ranges from that, of
nearly pure water (1 centipoise at. 2Q.?"C) to considerabl y higher v«3luec>.
However, very few measured values, of waste viscosity have boon obtained in
surveys of exist.ing injection wells (Warner, 1973; U. S. environments 1 Pro-
tection Agency, 1974), so the full range is not well characterised. The vis-
iQsity of a waste will increase with increasing dissolve'! solids content. ,•< r' 'ie;jl iir n;(iv
i nf 1 uenro *: 1 u i d vi '-.cos i !.y .
-------
Temperature
Variation in wastewater temperature may affect corrosion rates and
other chemical reactions and does affect viscosity as previously explained.
Generally, corrosion rate increases with increasing temperature. This
is particularly true when corrosion is due to the presence of mineral acids
in water, resulting in hydrogen evolution. However, in waters which are cor-
rosive due to the presence of dissolved oxygen, the corrosion rate in an open
system increases with increasing temperature only until the temperature be-
comes high enough to cause an appreciable decrease in the oxygen solubility.
Further temperature increase beyond this value results in a decrease in the
corrosion rate for such open systems, where the oxygen is free to escape.
In a closed system, the oxygen cannot escape and the corrosion rate continues
to increase with increasing temperature (Ostroff, 1965). Wastewater may be
in an open system as it passes through the plant and pretreatment process.
It will be in a closed system once it enters the well.
As with corrosion, most chemical reactions are enhanced by increase of
temperature. According to the general rate constant equation, which can be
found in physical chemistry texts,, the rate of reaction varies with the loga-
rithm of increasing temperature.
If a wastewater is at ambient temperature prior to injection, its tem-
perature will be increased during injection according to the local geothermal
gradient, which was previously defined and discussed in Chapter 2. This
should be kept in mind in considering the reactivity of a wastewater.
Suspended Solids Content
Suspended solids must normally be removed from a wastewater to the high-
est degree practicable prior to injection, because they will otherwise be fil-
tered out by the reservoir rock and will thus plug the pores and reduce per-
meability. The plugging effect of suspended solids is inversely related to
the size of the pores in the reservoir; however, any sandstone with inter-
granular permeability will be plugged if a significant amount of suspended
sol ids remains in the wastewater. It is possible for carbonate rocks with
solution permeability or fractured reservoirs to accept wastewaters contain-
ing suspended material; but this characteristic should not be depended upon
and filtration omitted from the pre-injection treatment system, until the cap-
abilities of the injection horizon have been established by testing.
Suspended solids can originate as chemical precipitates, as particles
from materials handled in the industrial process, as corrosion reaction pro-
ducts, as clay or silt--perhaps from ore processing, and probably in other
ways. Suspended solids content, is determined by filtration and is reported
in mg/Ł. The standard filter used for wastewater analysis is a glass fiber
filter disk (American Public Health Association, et. a!., 1976). This test
is a crude one, since wastewater treatment plants demand less than complete
particle removal. For injection water, use of a membrane filter with a 0.47
micron pore size is recommended (Ostroff, 1965). Sadow (1972) states that
only detailed laboratory testing of core samples or field testing can ra-
160
-------
ionally define the requirement for solids removal in any particular case.
An indirect indication of suspended solids content is turbidity as
determined with some type of turbidimeter. According to the American Public
Health Association, et. al. (1976), the optical property of turbidity cannot
be directly correlated with suspended solids content, but turbidity measure-
ments provide an inexpensive and continuous means of evaluating the relative
clarity of treated injection water. In fact, it is possible to arrange for
automatic recycling of the wastewater or shut-down of the injection well if
an unacceptable turbidity level is measured in the treated wastewater.
Gas Content
Entrained gas bubbles can, just as suspended solids, plug the pores of
the injection reservoir. Therefore, it may be necessary to degasify some
wastewaters to prevent such mechanical plugging. Dissolved gases do not pose
any potential for mechanical plugging, but dissolved oxygen, hydrogen sulfide,
carbon dioxide, and perhaps other gases promote corrosion of surface and well
equipment and may also be involved in reactions that produce plugging pre-
cipitates. Degasification to reduce corrosion or to prevent chemical reac-
tions may, therefore, be desirable.
Corrosion of iron by dissolved oxygen in the absence of any other in-
fluencing gases or chemicals proceeds as follows (Ostroff, 1965):
Fe + 2H+ * Fe++ + 2H°
2H° + 1 02 ? H20
2Fe++ +1 0 + H00 -> 2Fe+++ + 20H~
2 2 2
In a closed system (out of contact with air), the reaction will conti-
nue only until the dissolved oxygen is consumed. In a system in contact with
air, the oxygen supply is replenished and corrosion continues. The surface
facilities for an injection system may be open or closed. Once the waste-
water enters the injection pump, it is in a closed system. Oxygen has beer;
found to enter supposedly closed systems through loose pump packing and by
various other means (Wright, undated).
The presence of dissolved salts enhances corrosion by oxygen, but
cause solubility of oxygen decreases with increasinq salt content, corn
from ox.yqen may br less in very highly saline- solution', than if is in w
sa 1 i ne sol ut. i ons .
Carbon dioxide dissolved in water ivsn tont.ribufo to the ;..orros inn
steel, but. for equal concentrations it, is '"uch less rnrros; v«- (Mar: o.-y.jf
(OsfroH, l%::'. ';•.',it'"- rontainin'.] bot'i ,;.isr". is ;:mv> -, ;."TOS i v ' c S^T!
-------
than water which contains only an equal concentration of one of these
gases (ibid.).
Water containing hydrogen sulfide is corrosive. Dissolved hydrogen
sulfide forms a weak acid; and, in the absence of oxygen, dissolved hydrogen
sulfide will attack iron and nonacid-resistant alloys. Water containing
both oxygen and hydrogen sulfide may even be corrosive to acid-resistant
alloys (Ostroff, 1965).
CHEMICAL CHARACTERISTICS
Dissolved Constituents
The dissolved chemicals in a wastewater contribute to its properties
including reactivity, toxicity, density, and viscosity. As mentioned pre-
viously, these resultant properties can be determined without a chemical
analysis, but they can be better understood if a complete chemical analysis
is available.
A useful measurement of the dissolved chemicals is the total dissolved
solids content, often abbreviated as TDS. The total dissolved solids con-
tent can be obtained by adding the weights of each of the individual consti-
tuents or by evaporating a filtered sample to dryness and weighing the resi-
due. A direct analysis is a good check on the value obtained by adding the
results of the other analyses.
An excellent indicator of the total dissolved solids content of an
aqueous solution can be its conductivity or resistivity. In chemical solu-
tions containing many ions, it is necessary to develop an empirical relation
between dissolved solids content and conductivity, but an estimate of the
dissolved solids content can be made using a graph such as that shown in
Figure 3-8, which is for sodium chloride solutions. This estimate is less
satisfactory when the proportions of different ions vary as well as the con-
centrations. Conductivity can be monitored as an approximate indicator of
variations that may occur in wastewater composition.
Dissolved salts have a marked influence on the corrosivity of water.
Both the anion and cation kinds affect the corrosion rate as does concen-
tration. For example, the order of decreasing corrosiveness of cations has
been given as ferric > chromic > aluminum > potassium > sodium > lithium >
barium > strontium > calcium > manganese > cadmium > magnesium (Borgman,
1937). However, the type of salt in solution is equally as important as the
kind of ion (Uhlig, 1963). Alkali metal salts (e. g., NaCl, KC1, Na2SO^)
and acid salts (e. g., FeCl2 AlCl^) are corrosive to iron. Alkaline salts
(e. g., Na2C03, Na3P(L) passivate iron and are corrosion inhibitors above
pH 10 and may also act as corrosion inhibitors below pH 10 by forming effi-
cient diffusion barriers such as ferric phosphate. Oxidizing salts may be
corrosive (e. g., FeCl3, CuClo) or they may be inhibitors (e. g., Na^CrO*,
NaN02, KMn04).
Generally, corrosiveness increases with increasing salt concentration
until a maximum is reached, then corrosiveness decreases. The initial increcse
162
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in corrosion rate at low salt concentrations is probably a result of conduc-
tivity increase. The decrease in corrosion rate at high salt concentrations
(> 30,000 mg/Ł in NaCl ) results from the decreased solubility of oxygen
(Uhlig, 1963).
Examination of the dissolved solids composition of a wastewater and
comparison with the analysis of formation water may indicate the potential
for reactions between the two waters. Reactions between injected and inter-
stitial water that form precipitates are undesirable because the precipitates
may plug the pores of the injection unit, reducing the porosity and permea-
bility. Selm and Hulse (1959) listed the reactions between injected and in-
terstitial fluids that can cause the formation of plugging precipitates -
(1) precipitation of alkaline earth metals such as calcium, barium, strontium,
and magnesium as relatively insoluble carbonates, sulfates, orthophosphates,
fluorides, and hydroxides; (2) precipitation of metals such as iron, alumi-
num, cadmium, zinc, manganese, and chromium as insoluble carbonates, bicar-
bonates, hydroxides, orthophosphates, and sulfides; and (3) precipitation of
oxidation-reduction reaction products. Headlee (1950) discussed such reac-
tions in detail .
The dissolved solids in wastewater may also react with formation min-
erals. The most common reaction of this type is reaction of acidic wastes
with carbonate reservoirs as previously mentioned. Ion exchange may also
take place. Ion exchange affects the ionic composition of the injected wa-
ter. This may be a means of selectively removing some ions from the waste-
water. For example, radioactive ions may be absorbed and replaced by inno-
cuous ones. Such reactions are discussed further in the section concerning
reactions with formation minerals.
Wastewater pH is an indicator of corrosi veness to equipment and possibly
of reactivity with the subsurface reservoir. Wastes with a low pH have been
the principal source of injection system failure from corrosion. Acidic
wastes also have caused well failures through collapse of the well bore after
long periods of erosion due to dissolving of limestone and dolomite in the
subsurface reservoir. Some reaction with a carbonate reservoir can, however,
be desirable, because it will maintain and even increase the porosity and
permeability of such a reservoir.
The cniros i venoss of .1 wastewater to iron generally increases as pH de-
creases. At very low pil values (less than 4), the iron corrosion products
are soluble, resulting in direct contact between the acidic solution and the
iron surface.1 and consoqucM* rapid corrosion. In the oH range of 4 to 9.b,
the i ror: surface is coated by corn's io'i reaction products and corrosion pro-
gresses -ore 'Jowly. However, hio'Jv aHal'im- solutions "iay cJso be corro-
sive. for cxii"!iJt', at. e:< f.re"!el y r i ;': i.
-------
ferric chloride or ferric sulfate solutions to above pH 4 leads to precipi-
tation of the ferric iron.
An increase in pH of water in the formation pores can also cause loss
of permeability in formations that contain so-called "sensitive" clays
(Hughes, 1950; Baptist and Sweeney, 1955).
Chemical Stability
Stability of the chemical compounds in the injected wastewater is de-
sirable. An unstable compound may precipitate during or after injection and
cause plugging. The influence of temperature and pH changes in initiating
instability have been individually pointed out, but have not been quantified.
Also these factors can obviously act simultaneously, making interpretation
difficult.
A means of anticipating instability in a system affected by more than
one variable is through use of a saturation or stability index. Several such
indices have been developed including those by Langelier (1936), Ryznar (1944)
Larson and Buswell (1942), and Stiff and Davis (1952). The first three in-
dices are applicable to waters of low ionic strength, while the Stiff and
Davis index is intended for use with concentrated solutions, such as highly
saline ground waters. As an example of the use of such indices, the Stiff
and Davis (1952) stability index for calcium carbonate is:
SI - pH - k - pCa - pAlk (5-1)
In equation 5-1, k is an empirical constant used to compensate for var-
ious ionic strengths and temperatures. The values of k, pCa, and pAlk are
taken from graphs (Figures 5-1 and 5-2). A positive index indicates scale
formation and a negative index indicates corrosion.
The following example of the use of the stability index was taken from
Ostroff (1965).
From the water analysis in Table 5-2, the concentration C of each ion
in moles per 1,000 grams of water is calculated using the relationship:
Q _ epm
^ (5-2)
z(l,000 SpGr - _
where epm = concentration of the ion, epm
z = valence of the ion
SpGr = specific gravity of the brine
TDS = total dissolved solids, ppm
164
-------
-------
10,000
Ca HCO
1000
rO
o
o
X
rO
O
o
o
o
E
Q.
CL
iOOr-
05
i 5 20
p Co , p A I k
2.5
FIGURE 5-2. GRAPH FOR CONVERTING PARTS PER MILLION OF CALCIUM AND
ALKALINITY TO pCa AND pAlk (FROM STIFF AND DAVIS, 1952).
166
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This gives the following results:
TABLE 5-2. WATER ANALYSIS USED IN SAMPLE CALCULATION OF CALCIUM CARBONATE
SATURATION USING STIFF AND DAVIS INDEX (OSTROFF, 1965)
Component
Carbonate (COp
Bicarbonate (HCO^)
Sulfate (SOJ)
Chloride (CT)
Iron (Fe++)
Calcium (Ca++)
Magnesium (Mg++)
Sodium (Na+)
ppm
-
46
7,530
88,300
14
8,570
2,819
45,195
epm
-
0.7
158
2472
0.4
428
231
1965
Moles/1 ,000 gm
-
0.001
0.083
2.599
0.000
0.225
0.121
2.066
Using these molalities, the ionic strength u is calculated.
=^[(0.001) (1) + (0.083) (4) +(2.599) (1) + (0.225) (4)
+(0.121) (4) + (2.066) (1)] - 3.19
Then, from Figure 5-1, the value of k, at , 3.19 and at. the analysis
temperature of 77°F~ (25°C) , is found to be 2.96.
The next step is to enter the ppn; CaM ;" 8,570 and ppn; HCO,, 46
(obtained fro::: the water analysis) as the ordinate of f kjun1 l)-',-'~! Readinij
the abscissa, the pCa of 0.67 and the pAlk is 3.12.
Then, siihs titu t i n<\ in i(]i,d f.ion :S-1, the i;t,ah i 1 i ! v i'K'iex i •-. di 11 u 1 -\ led
as fol1ows:
-------
This indicates that the water is corrosive and also undersaturated with res-
pect to calcium carbonate.
Ostroff (1965) discusses the stability of magnesium carbonate, magnes-
ium hydroxide, calcium sulfate, barium sulfate, iron, and also silica.
Barnes (1972) suggests a thermodynamic approach to predicting the stability
of inorganic compounds in solution.
Dissolved organic compounds may also be unstable. Selm and Hulse
(1959) list polymerization of organic chemicals as a source of plugging pre-
cipitates.
In addition to the predictive methods of analyzing for chemical sta-
bility, analysis can be empirical. The water in question can be subjected
to the pressure and temperature that it will experience in the subsurface
and it can then be observed to evaluate its tendency to form precipitates
over an extended period of time.
Reactivity
Wastewater can react with the materials in the mechanical system,
aquifer fluids, and aquifer minerals. As has been described previously in
this chapter, knowledge of the chemistry of the wastewater along with the
materials of construction, the chemistry of aquifer fluids, the mineralogy
of the injection horizon and the subsurface temperature and pressure allow
prediction of some potential reactions. Further discussion of the problems
of reactivity and prediction of their likelihood of occurrence is given in
this section.
Reaction with System Components --
Corrosion of metals in injection systems may be by chemical, electro-
chemical, or microbiological means. In aqueous systems, corrosion is prin-
cipally electrochemical. Some factors that influence electrochemical cor-
rosion of steel are dissolved oxygen, dissolved salts, pH, temperature,
pressure, and flow rate of the corroding solution. The influence of all but
flow rate have previously been discussed in this chapter. Generally, cor-
rosion rates increase with the velocity of flow of the corroding water, but
not uniformly, because effects such as turbulence and the mechanical removal
of corrosion products become involved at high velocities (Ostroff, 1965).
Forms of corrosion include uniform or thinning corrosion, pitting cor-
rosion, intergranular corrosion, and galvanic corrosion (Ostroff, 1965).
Uhlig (1963) also includes dezincification and parting and cracking, and
Henthorne (1972) adds erosion corrosion and crevice corrosion. In uniform
corrosion, the entire surface of the metal is corroded and thinned by a uni-
form amount. Rate of uniform corrosion is reported in inches per year (ipy),
mills per year (mpy, one mill = 0.001 inches), or milligrams per square deci-
meter per day (mdd). According to Uhlig (1963) steel, for example, corrodes
at a relatively uniform rate in sea water equal to about 25 mdd or 5 mpy.
Conversion of weight loss to depth of attack or vice versa requires know-
ledge of metal density. Table 5-3 provides this information.
168
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TABLE 5-3. DATA FOR CONVERSION OF WEIGHT LOSS TO DEPTH OF CORROSION
AND VICE VERSA. TO OBTAIN DEPTH OF PENETRATION, MULTIPLY
mdd BY 0.00144/DENSITY TO OBTAIN INCHES PER YEAR. TO
CONVERT FROM ipy TO mg PER SQ. DECIMETER PER DAY (mdd)
MULTIPLY BY 696 X DENSITY (UHLIG, 1963).
Metal
Al uminum
Brass (red)
Brass (yellow)
Cadmi urn
Col umbium
Copper
Copper-nickel (70-30)
Iron
Iron-silicon (Duriron) (84-14.5)
Lead (chemical )
Magnesi urn
Nickel
Nickel-copper (Monel ) (70-30)
Si 1 ver
Tantdl uni
Ti tan i ui"
Tin
Zi nc
Zi rrnn i jr:
Density
gm/cc
2.72
8.75
8.47
8.65
8.4
8.92
8.95
7.87
7.0
11.35
1.74
8.89
8.84
10.50
16.6
4.54
7 . 29
7 . i -•;
t, ,,i.
0.00144
Density
0.000529
0.000164
0.000170
0.000167
0.000171
0.000161
0.000151
0.000183
O.C00205
0.000127
0.000826
0.000162
0.000163
0.000137
0.0000868
0.00031 7
'!.0:')^19:::;
n _ ;").']'}/']/'
i j Y i •; v '?
696 X Density
1890
6100
5880
6020
5850
6210
6210
5480
4870
7900
1210
6180
6140
7300
11550
3160
5070
:", ''•' /"f ]
• ",''. 'K';
-------
Metals can be classified according to their corrosiveness and their suit-
ability for various applications as shown below (Uhlig, 1963):
(1) < 0.005 ipy
Metals in this category have good corrosion resistance
to the extent that they are suitable for critical parts,
e. g., valve seats, pump shafts, springs, etc.
(2) 0.005 to 0.05 ipy
Metals in this group are satisfactory if a higher rate of
corrosion can be tolerated; e. g., for tanks, piping, valve
bodies, etc.
(3) > 0.05 ipy
Usually not satisfactory.
In pitting corrosion, attack is greater in localized areas than over
the surface as a whole. Depth of pitting is sometimes expressed by a pitting
factor, which is the ratio of the deepest pits to the average depth of cor-
rosion as determined by weight loss. Ostroff (1965) gives a laboratory pro-
cedure for performance of a weight loss test.
Intergranular corrosion occurs with alloys when a difference in poten-
tial exists between the grain boundary and the grain. The smaller grain
boundary acts as the anode. This type of corrosion is particularly serious
with aluminum alloys containing copper and austenitic stainless steels con-
taining carbon.
Galvanic corrosion occurs where two different metals or alloys come
in contact. The severity of galvanic corrosion depends upon the difference
in potential between the two metals, and the relative size of the cathode
and anode areas. The galvanic series for metals and alloys in sea water is
shown in Table 5-4. Active metals are at the top of the series. Coupling
a metal near the top with one near the bottom will cause galvanic corrosion
of the more active metal.
If the area of the active metal is very large compared with the area
of the less active metal, corrosion will not be so severe. Polarization will
also modify the amount of current flowing during the corrosion reaction.
In addition to visual observation and weight loss testing, corrosion
rates can be measured or estimated by use of electrical resistance corrosion
probes, and by analysis of the corroding water for corrosion products. Well
casing or tubing can also be examined in place for corrosion with caliper
logs, electromagnetic logs, televiewer logs, and down-hole television in-
spection. The borehole methods are discussed in Chapters 3 and 7.
Electrical resistance corrosion probes depend on measuring the change
in resistance of a metal specimen as it loses volume through corrosion.
170
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TABLE 5-4. GALVANIC SERIES FOR METALS IN
SEA WATER (JELLINKE, 1958).
Active or Anodic End
Magnesium
Zinc
Alclad 3S
Aluminum 3S
Aluminum 61S
Aluminum 63S
Aluminum 52
Low steel
Alloy steel
Cast iron
Stainless steels (active)
Type 410
Type 430
Type 304
Type 316
Ni-resist
Muntz metal
Yellow brass
Admiralty brass
Aluminum brass
Red brass
Copper
Aluminum bronze
Composition G bronze
90/10 Copper-nickel
70 + 30 Copper-ni
70 + 30 Copper-ni
Nickel
Inconel
Si 1 ver
Stainless steels
Type 410
Type 430
Type 304
Type 316
Mo n e 1
Has to Hoy C.
Ti tani mi;
ckel-low iron
ckel-high iron
(passive)
o or Cathodk S n;l
-------
Probes are available in a variety of metals and alloys. Commercial measuring
instruments are also available for use in conjunction with the probes. Cor-
rosion prevention is covered in conjunction with wastewater pretreatment and
system design.
Microorganisms can contribute to corrosion in several ways, one of
which will be described. Although many types of bacteria can contribute to
corrosion, only a few have been found to be of major importance in oil field
operations (Sharpley, 1961), which are similar to disposal well operations.
Sulfate-reducing bacteria (Desulfovibrio desulfuricans) are common
and the most important from a corrosion standpoint. They are an anaerobic
bacteria, but will survive in the presence of dissolved oxygen, where they
may grow under scale, debris, or other bacterial masses where oxygen cannot
penetrate (Baumgartner, 1962). In the process of reducing sulfur in sulfate
ions to the sulfide form, these bacteria utilize hydrogen which increases
corrosion by depolarizing the cathode in an electrochemical system. The
sulfide ion resulting from sulfate reduction can combine with ferrous iron
at the anode, forming ferrous sulfide, a commonly observed plugging precipi-
tate.
A possible reaction between radioactive wastewater and metals in the
injection system is the selective deposition of radioactive metals in place
of the inert metals in the system. This process would cause the system com-
ponents to become radioactive and possibly present some special problems in
their handling. Trevorrow et. al. (1977) discuss the potential for this
problem in conjunction with injection of low-level radioactive waste from
nuclear fuel reprocessing plants.
Reaction with Formation Waters --
The potential reactions from mixing of injected and interstitial waters
have been discussed in the section entitled "Dissolved Constituents." Waters
that can be mixed without the formation of precipitates are termed compatible.
Henkel (1953, 1955) reported testing brine and wastewater compatibility by
allowing a mixture of the two liquids to stand for from 8 to 24 hours at the
approximate aquifer temperature. The mixture is considered compatible if it
remains free of precipitates. Others (Lansing and Hewett, 1955; MacLeod,
1961) have suggested that this criterion may not be entirely satisfactory
in all cases, since reactions may require considerable time for completion
and because gaseous reaction products may also cause reduction in permeabi-
lity. Ostroff (1965) describes a procedure for compatibility testing and
notes that it may be necessary to observe the test for a considerable length
of time if an induction period is required before the formation of precipi-
tates. Ostroff also suggests that, if the possibility of reaction is sus-
pected but not observed, it is advisable to seed the water with crystals of
the salt that is most likely to deposit to stimulate the suspected reaction.
In testing for compatibility, the use of water from the proposed in-
jection interval rather than a synthesized formation water is recommended,
if possible, since even small differences in water chemistry can cause un-
expected reactions (Lansing and Hewett, 1955). In addition, synthesizing a
172
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particular formation water in the laboratory may be impossible, because nat-
ural brines apparently supersaturated in certain salts are not uncommon (Le-
welling and Kaplan, 1959).
Reactions with Formation Minerals --
A small number of minerals comprise nearly the entire mass of sandstone
aquifers. The average sandstone, as determined by Clarke (1924), consists
of 66.8 percent Si02 (mostly quartz), 11.5 percent feldspars, 11.1 percent
carbonate minerals, 6.6 percent micas and clays, 1.8 percent iron oxides,
and 2.2 percent other minerals. Limestone and dolomite aquifers are primar-
ily CaC03 and CaMg(COo)2, respectively, but impure ones may contain as much
as 50 percent noncarbonate constituents such as Si02 and clay minerals.
Quartz, the main constituent of sandstones, is the least reactive of
the common minerals, and for all practical purposes can be considered non-
reactive except in highly alkaline solutions (Roedder, 1959). Clays have
been demonstrated to react with highly basic or highly acidic solutions
(Grim, 1953; Nutting, 1943; Murata, 1943). A waste would not necessarily
need to be highly acidic to attack an aquifer mineral, since some relatively
v^akacids may strongly attack certain clay minerals (Grim, 1953; Nutting,
1943). The degree of reaction of feldspars and micas with injected solutions
is not certain, but some reaction would no doubt occur (Roedder, 1959).
Sandstone aquifers are often cemented with carbonate minerals, which
react with acid solutions. Reaction of acid wastes with the carbonate cement
in sandstone would cause an evolution of CC^ that could both increase the
pressure and reduce permeability. In the special case of acid aluminum
nitrate wastes, Roedder (1959) has shown that the reaction of the waste with
CaCO^ results in a gelatinous precipitate that would plug the pores in a
sandstone containing sufficient carbonate minerals. Sandstones also commonly
contain gypsum and limonite as cementing material, and these two minerals can
be dissolved and reprecipitated to cause blocking of pores (Yuster, 1939;
Krynine, 1938).
The brines in deep limestone, dolomite, or calcareous sandstone aqui-
fers will, in most cases, be in chemical equilibrium with the aquifer, and
precipitation or solution will not occur.
If injected wastes are at a lower pH than aquifer waters, solution of
the carbonate aquifer material may occur. This reaction could be beneficial,
as long as no gelatinous precipitates result, such as those that occur when
acid aluminum nitrate wastes react with CaCOo. If injected wastes mix with
aquifer water and raise its pH, dissolved salts could precipitate and cause
plugging of the pores.
Clay minerals are common constituents of sedimentary rocks. Roedder
(19b9) stated that sandstones containim] less than n.l percent (.lav minerals
:nay not exist anywhere in the United States, except possibly in SUM I 1 depo-
sits nf exceedinqly pure4 qlass sand. Clay minerals are. known to reduce the
permeability of sandstone to water as ensnared with its permealii 1 i t.y to
-------
1965). The degree of permeability reduction to water as compared with air
is termed the water sensitivity of a sandstone by Baptist and Sweeney.
The water sensitivity of clay-bearing sandstones increases with decreas-
ing water salinity, decreasing valence of the cations in solution, and in-
creasing pH of the water (Johnston and Beeson, 1945; Hughes and Pfister,
1947; Baptist and Sweeney, 1955). Jones (1964) described work where he
gradually reduced the salt concentration of brines during flow tests in clay-
containing rocks. He found that water permeabilities remained essentially
constant with this procedure, in contrast to the drastic permeability de-
crease which would occur if the salt concentration were changed to the final
low value in one step. Mungan (1965) confirmed Jones' findings and also in-
vestigated the effect of pH on permeabilities. Generally, high-pH solutions
caused severe permeability damage, particularly where a large change in pH
of flowing solutions was noted. Browning (1964) had also noticed this effect
where hydroxyl ions promoted the cleavage of clay-mineral stacks. One inter-
esting observation by Mungan was the silica enrichment of the effluent from
the cores. He believed that amorphous silica was being dissolved by the
high-pH solutions and, because this silica might be the cementing agent for
sand grains, fines could be released to migrate and, eventually, to obstruct
flow passages. Permeability damage caused by the high-pH solutions was more
noticeable at higher temperatures. The water sensitivity of a sand depends
on the type of clay mineral as well as the amount. Hughes (1950) pointed
out that the properties that cause clay minerals to reduce sandstone's per-
meability to water are exhibited by montmorillonite to a marked degree, by
illite to a lesser degree, and by kaolinite to a relatively unimportant de-
gree. Concepts that can be used to explain the above-mentioned observations
have been discussed by Van Olphen (1963). Water sensitivity of sandstones
can be determined directly by permeability tests with various waters and air
or indirectly by X-ray diffraction, differential thermal analysis, or water
vapor absorption measurements (Baptist and Sweeney, 1955; Johansen and Dun-
ning, 1958).
Hewitt (1963) developed a series of tests that detect the degree of
water sensitivity of rocks. His system includes mineral identification,
solids-swelling tests, microscopic examination, and flow tests. The complete
program requires specialized equipment, expertise in this area, and consid-
erable time, but the data obtained can be of considerable value.
Repairing permeability damage after a water-sensitive rock has been
exposed to a brine of lower salinity is normally difficult. Hower, et. al.
(1972) suggest that this is because when the normally-stacked clay crystals
adsorb additional water, they tend to separate and build a "house of cards"
structure. Such a structure develops through the attraction of the positive-
ly charged edges of the clay crystals to the negatively charged faces. When
the salt content of the brine is then increased to the original concentration,
the crystals are not restacked in an orderly manner but attain a compressed
"house of cards" configuration.
Hower et. al. (1972) point out that polar organic compounds can be
adsorbed on surfaces of rocks, particularly the silicates. Silicates, in
their natural state, are negatively charged and will adsorb organics through
174
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electrostatic attraction, hydrogen bonding, and van der Waals forces. The
greatest charge density is normally found on clays, particularly the mont-
morillonite and mixed-layer clays, which would make the electrostatic attrac-
tion force the greatest for these minerals. It has been shown (Hower, 1970)
that up to 0.55 g of some surfactants can be adsorbed by 1 q of montmorill-
onite. Quartz has a much lower charge density, but it can also adsorb a sig-
nificant quantity of positively charged organic chemicals. It is possible
to alter the wettability of some rocks from water-wet to oil-wet by adsorp-
tion. This change in wettability and/or extensive adsorption of other polar
organic chemicals on the rock around the well bore may cause severe permea-
bility reduction. Some of these adsorbed chemicals can be washed from the
rock with water, whereas others, particularly those carrying a positive
charge, are very difficult to remove. In some cases, a specific solvent
can be used to dissolve the adsorbed organics. The problems relating to
permeability reduction by polar organic adsorption are normally more severe
in sandstone than in carbonate reservoir rocks.
Toxicity
Toxic chemicals are defined in the Federal Water Pollution Control Act
Amendments of 1972 as those pollutants or combinations of pollutants, includ-
ing disease causing agents, which after discharge and upon exposure, inges-
tion, inhilation or assimilation into any organism, either directly from the
environment or indirectly through food chains, will, on the basis of the in-
formation available, cause behavioral abnormalities, cancer, genetic muta-
tions, physiological malfunctions or physical deformations in such organisms
or their offspring.
Sources of information on the toxicity of inorganic and organic chemi-
cals include "Clinical Toxicology of Commercial Products" (Gleason, et. al.,
1969), the "Toxic Substances List" (Christensen, et. al., 1974), "Water Qual-
ity Criteria" (McKee and Wolf, 1963) and "Water Quality Criteria" (Federal
Water Pollution Control Administration, 1968), "Water Quality Criteria-1972"
(National Academy of Sciences, 1974) and "Quality Criteria for Water" (U. S.
Environmental Protection Agency, 1976).
Also, the National Technical Information Service of the U. S. Depart-
ment of Commerce, Springfield, Virginia, maintains a Toxicology Information
Response Center and the Library of Congress (1969) has published a document
entitled, "A Directory of Information Resources in the United States - Gen-
eral Toxicology." In the event that chemicals are involved for which there
is no toxicity information, consultants are available to make the necessary
t.ox ic i ty eval uation .
It is suggested that all wastes to be injected should be characterized
as to their toxicity, particularly to hui'ians. !t is not intended or expected
that an injected wastewater will ever enter the biosphere-, but the injector
and fiu> regulatory authorities should be awtin1 of its toxicity so that, appro-
priate precautions i.an In- provided for in the dps ion, operation, and nonitor-
ino oj" * hi1' svst (•"•-.
-------
A scheme for rating the toxicity of a compound that is used by Gleason,
et. al. (1969), is shown below:
TOXICITY RATING CHART
Toxicity Rating or Class
Probable LETHAL Dose (human)
mg/kg for 70 kg man (150 Ib)
6 super toxic
5 extremely toxic
4 very toxic
3 moderately toxic
2 siightly toxic
1 practically non-toxic
less than 5
5-50
50-500
500-5,000
5,000-15,000
above 15,000
a taste (less than 7 drops)
between 7 drops and 1
teaspoonful
between 1 teaspoonful and
one ounce
between 1 ounce and 1 pint
(or 1 Ib)
between 1 pint and 1 quart
more than 1 quart
This chart classifies compounds according to the probable amounts that
constitute a lethal dose to a human. As discussed above, it is not expected
that an injected waste will ever be ingested by a human. However, it would
be apparent to both regulator and injector that no margin for error exists
in the handling of super-toxic solutions. On the other hand, it might be
judged reasonable to permit some calculated amount of risk when dealing with
a non-toxic solution such as a sodium chloride brine.
BIOLOGICAL CHARACTERISTICS
Bacteria present in injected wastewater may themselves cause corrosion
or plugging of conduits and reservoir rocks. The role of bacteria in cor-
rosion has previously been discussed. Bacteria may also promote reactions
within the wastewater that may change the wastewater chemistry and form pre-
cipitates or gases.
Microorganisms can contribute to plugging injection wells and fouling
flow lines and equipment in several different ways. By actual growth, these
organisms can produce masses that will plug wells and reduce flow in lines.
Iron bacteria can cause the precipitation of iron as ferric oxide, resulting
in an accumulation of this material in injection wells. Corrosion products
resulting from increased corrosion caused by sulfate-reducing bacteria can
also accumulate in wells or on filters, reducing flow or causing plugging.
176
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The microorganisms mentioned as causing microbiological corrosion can
grow into sufficiently large masses to cause plugging. This is particularly
true of the slime formers and iron bacteria. In addition, algae may grow in
fresh-water systems. Algae require sunlight for growth, so that problems
with algae are confined to injection systems where open ponds or holding tanks
are used. Fresh-water algae grow on the surface of the water and may serve
as a source of food for bacteria. If they form a blanket over a pond or
tank, the reduction in oxygen intake into the water can make conditions ideal
for growth of sulfate reducers in the areas of deep water. Algae growths
often slough off and plug pipes and filters.
DiTommaso and Elkan (1973) reported having discovered the presence of
bacteria in the sandstone injection interval of the Hercules Chemical, Inc.,
plant at Wilmington, North Carolina. In that case, an organic wastewater,
the by-product of dimethylterepthalate, was injected and subsequently decom-
posed to form methane at the expense of dissolved organic carbon. Large in-
creases in the iron content of water in the reaction zone were also observed.
The potential implications of such reactions have not been explored, but they
could be beneficial, e. g., decomposition of the injected waste or they could
be detrimental, e. g., plugging of the aquifer.
Procedures for testing of waters for the presence of microorganisms are
given by the American Public Health Association (1976), the American Petro-
leum Institute (1965), and Ostroff (1965). Ehrlich (1972) comments that the
following points should be considered when designing a testing program:
1. The bacterial-growth potential of undiluted waste solution
and mixtures of waste solution and native formation water
should be determined.
2. Material from the formation, preferably from well cores,
should be added to the test solutions.
3. Oxidation-reduction potentials of the test solutions
should be adjusted to values which are typical of the
formation. Oxygen should be excluded from the solutions
if appropriate.
4. The test should be conducted at temperatures and pressures
that approximate the operating conditions expected under
waste injection.
Ostroff (1965) notes that the mere presence of bacteria in a water does
not necessarily mean that they will cause a problem in the injection system.
Determination of the potential for one; ineerinq problems is linked to the abil-
ity of the bacteria present; to flourish in the environment of the injection
system. Conversely, low bacterial count", do not necessarily mean that bac-
teria arc not i crnbl em, since1 t.hev nay be thriving in an isolated lo;aticm.
" hir. , '.here can be -.1 lack, of correlation betv.'een b;i< ferial analyse', anil the
lama f;e tha ' ma y n; cur i n a sy-. fern .
-------
WASTEWATER SAMPLING AND ANALYSIS
Thus far, in this chapter, the focus of the discussion has principally
related to the influence of the various physical, chemical, and biological
characteristics of wastewater upon the injection system and injection oper-
ations. Some mention of testing procedures has been made, where the methods
are unusual and/br are importantly related to the usefulness of the resulting
data for injection purposes. Wastewaters under consideration for injection
should be more broadly characterized than has yet been indicated, because
alternative forms of handling must be examined before injection is selected
and because more information may be needed to plan a pre-injection treatment
process.
Conway (1968) listed the basic parameters for the characterization of
a wastewater in terms of its source, flow, physical properties, chemical com-
position, and biological effects (Table 5-5). Table 5-5 overlaps Table 5-1,
but it also contains items not included in Table 5-1 that are needed for the
purposes mentioned above.
Little mention has been made of sampling procedures. Wastewater analy-
ses are only meaningful if the waste has been properly sampled. Acceptable
sampling methods are outlined in "Standard Methods for the Examination of
Water and Wastewater" (American Public Health Association, et. al., 1976)
and the American Society for Testing and Materials, Part 31, "Water" (1975).
Conway (1968) lists some common sampling pitfalls as: insoluble components
not collected in proper proportion to sample volume, peak discharges missed
by collecting grab samples instead of using compositing equipment, samples
not composited in proportion to flow rate and samples not properly preserved.
Excellent references are available that outline currently acceptable
methods for wastewater analysis. The analytical methods handbook of the
water supply and wastewater control professions is "Standard Methods for the
Examination of Water and Wastewater" (American Public Health Association,
et. al., 1976). The United States Environmental Protection Agency (1971)
has published a manual of analytical procedures selected for use by that
agency. Because either State or Federal permits will be required for injec-
tion wells, approved analytical methods should be used. The American Society
for Testing and Materials (1976) describes procedures accepted by that organ-
ization. Other useful references that discuss methods for water analysis
are Collins (1975), the American Petroleum Institute (1968), and publications
of the United States Geological Survey Water Resource Investigation Series,
for example, ones by Barnett and Mai lory (1971) and Goerlitz and Brown (1972).
WASTEWATER CLASSIFICATION
After the physical, chemical, and biological characteristics of a
wastewater have been evaluated, as described in Chapter 5, it can be classi-
fied for injection purposes. From an engineering viewpoint, the question
is: Can the wastewater be safely, efficiently, and economically injected
at the available site? Two additional questions that should be addressed
from both an engineering and a regulatory position are: Is injection the
178
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TABLE 5-5. BASIC PARAMETERS FOR CHARACTERIZATION
OF A WASTEWATER (CONWAY, 1968).
I. Source Information for the Individual Points of Origin
(A) Rate of discharge during production run (average and
maximum)
(B) Duration and frequency of production runs
(C) Waste components (see below)
(D) Likelihood of spills or abnormal discharges
II. Flow Data for Total Discharge
(A) Average daily flow rate
(B) Duration and level of maximum flow rate
(C) Maximum rate of change of flow rate
III. Physical Properties
(A) Temperature range
(B) Insoluble components: colloidal, settleable, floatable
(C) Color
(D) Odor
(E) Radioactivity
(F) Foamability
(G) Dissolved oxygen
(H) Corrosiveness
IV. Chemical Composition
(A) Known organic and inorganic components
(B) Chemical oxygen demand, total carbon, extractables
(C) pH, acidity, alkalinity
(D) Oxidizing or reducing agents (sulfides)
(E) Chloride ion
(F) Hardness (calcium and magnesium)
(G) Nitrogen and phosphorus
(H) Surfactants
(I) Chlorine demand
(J) Total dissolved salts
(K) Specific ions (As.Ba,Cd,Cr,CN,F,Pb,Se,Aq)
(L) Phenol
(M) Grease and hydrocarbons
V. Bioloqicdl Effects
(A) Biochemical oxyqen demand
(B) Pathogenic bacteria
(C) Chemical toxirity (aquatic life, bJ < t
-------
most environmentally and technologically desirable alternative in the specific
case? Injection may be technically and economically feasible, but still may
not be the most desirable alternative.
The procedure for examining the engineering feasibility is to consider
each of the characteristics discussed in this chapter and to evaluate their
effect on injection at the site in question. Unfortunately, there is no sim-
ple basis for ranking all of the factors to arrive at a quantitative value
that determines whether or not injection is feasible. Also, if a problem
exists, it may be possible to alleviate it by process modification, waste-
water pretreatment, or appropriate system design. There are few, if any,
wastewater characteristics that cannot be modified to render a liquid inject-
able. However, the desirability of injection as an alternative will be com-
promised if too extensive pretreatment or too elaborate system design are
required. For example, wastewater volume is one of the most constraining
characteristics and usually the first to be examined when considering injec-
tion. When the wastewater volume is too great to be accommodated by the
locally available injection intervals, possible solutions include modifying
the waste producing processes to reduce the volume, separation of waste
streams and injection of only selected ones, or a pretreatment step for vol-
ume reduction. The volume problem has frequently been solved by one of the
first two possible means. Pretreatment for volume reduction is much less
promising because the available processes, e. g., partial evaporation, re-
verse osmosis, and electrodialysis are expensive.
If it is determined that a wastewater is injectable, then the relative
desirability of injection, as compared with other alternatives, should also
be considered. This has been recognized by many. The Ohio River Valley Wa-
ter Sanitation Commission (1973), in adopting policy to guide the eight mem-
ber states, has stated:
"NOW, THEREFORE: Let it be resolved that the Ohio River Valley Water
Sanitation Commission does declare as a policy that wastewater
injection may be used when the regulatory authorities with legal
jurisdiction have considered other alternative methods of waste
management, and that, after weighing all available evidence, have
determined that:
I. Underground injection is the best available alter-
native in the specific circumstances of the case."
Comparison with other alternatives is desirable because, as was recognized
some time ago by the Subcommittee on Waste Disposal of the Committee on Sani-
tary Engineering and Environment, National Academy of Sciences-National Re-
search Council (Committee Reports, June 25, 1962 and January 20, 1964),
the injection of liquid wastes into a subsurface rock formation constitutes
the utilization of limited useful space, injection wells cannot be considered
for any type and quantity of waste. This question has occasioned suggestions
that many varieties of wastewaters that are produced should be categorized
with regard to their suitability for injection (Warner, 1965; Cleary and
Warner, 1969).
180
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Radioactive wastes have been classified according to their relative
radioactivity as high, medium, or low level by the U. S. Atomic Energy Com-
mission (1969) and a more comprehensive scheme using five categories has been
proposed by the American Institute of Chemical Engineers (1967). For a vari-
ety of technical and policy reasons, only the low level radioactive wastes
are currently considered likely to be disposed through injection wells (Bel-
ter, 1972). Piper (1970) proposed a classification similar to that used for
radioactive wastes for all industrial wastes. Van Everdingen and Freeze
(1971) expanded upon Piper's concept and also introduced the idea of "natural"
and "foreign" wastes. The Piper and Van Everdingen and Freeze classifications
are, however, based principally upon waste toxicity and have not received sig-
nificant support, as far as is known. This is because the other physical,
chemical, and biological characteristics must also be rated as should the
potential for treatment or disposal by other means.
In summary, a complete basis for classification of a wastewater for
injection remains to be devised, but the characteristics described in this
chapter are used on a judgemental basis for making this determination. If
injection is considered technically feasible, then other means of treatment
or disposal are compared to establish that injection is the best alternative
in the specific case.
-------
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CHAPTER 5
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Injection of Wastewaters. Ohio River Valley Water Sanitation Commission
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Collins, A. G. Geochemistry of Oilfield Waters. Elsevier Publishing Co.,
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Conway, R. A. "Treatment of Dilute Wastewater" in Industrial Waste Disposal.
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Ehrlich, G. G. "Role of Biota in Underground Waste Injection and Storage."
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Grim, R. E. Clay Mineralogy. McGraw-Hill Book Co., New York, New York.
1953. 384 pp.
Headlee, A. J. W. "Interactions Between Injected and Interstitial Water --
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Henkel, H. 0. "Surface and Underground Disposal of Chemical Wastes at Vic-
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Henkel, H. 0. 'Deep-Well Disposal of Chemical Wastes." Chem. Eng. Progress.
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Henthorne, M. "Understanding Corrosion." Chemical Engineering - Deskbook
Iss_ue. December 4, 1972. pp. 19-30.
Hewitt, C. H. "Analytical Technique for Recognizing Water-Sensitive Reservoir
Rocks." Journal Petroleum Technology. Vol. 15, No. 8. 1963. pp.
813-818.
Hower, W. F. "Adsorption of Surfactants on Montmoril 1onite." Clays and Clay
Minera]^. Vol. 18. 1970. pp. 97-105.
Hower, W. F. , Lasater, R. M., and Mihram, R. G. "Compatibility of Injection
Fluids with Reservoir Components." In Underground Waste Management and
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Hughes, R. V. and Pfister, R. J. "Advantages of Brines in Secondary Recovery
of Petroleum by Water- Fl ootii ng.i! American Inst. Mining Metall. Engi-
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Jellinek. "How Oxidative Corrosion Occurs." Chemical Engineering. Vol. 65,
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of Reservoir Rocks. U. S. Bureau Mines Rept. Inv. 5422. 1958. 9 pp.
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55.
Jones, F. 0. "Influence of Chemical Composition of Water on Blocking of Clay
Permeability." Journal Petroleum Technology. Vol. 16, No. 4. 1964,
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Krynine, P. D. "The Mineralogy of Water Flooding." Producers Monthly.
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184
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Land, C. S., and Baptist, 0. C. "Effect of Hydration of Montmorillonite on
the Permeability to Gas of Water Sensitive Reservoir Rocks." Journal
of Petroleum Technology. Vol. 17, No. 10. 1965. pp. 1213-1218.
Langelier, W. F. "The Analytical Control of Anti-Corrosion Water Treatment."
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Mungan, N. "Permeability Reduction Through Changes in pH and Salinity."
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CHAPTER 6
PRE-INJECTION WASTEWATER TREATMENT AND
SURFACE FACILITY DESIGN
To ensure success of a subsurface waste-disposal operation, surface pre-
injection treatment of the wastewater is generally required. Treatment can
be quite expensive, but it can make the difference between a successful, en-
vironmentally-cognizant operation and one subject to repeated difficulties
and even failure. The principal objective of pre-injection treatment is to
modify the physical and chemical character of a waste so that it is compati-
ble with the surface and subsurface equipment that is used and with the in-
jection interval and its contained water. Details of the problems that can
occur when incompatibility exists were discussed in Chapter 5. Table 6-1
is a brief summary of such problems along with suggested means for evaluating
and control 1 ing them.
As suggested in Table 6-1, pretreatment processes are not the only
means of solving some of the problems related to wastewater character. For
example, corrosion control can be achieved by use of corrosion-resistant mate-
rials and a buffer zone can be established to prevent reaction between inject-
ed fluids and aquifer water. The choice of control method will be dictated
by economics, engineering feasibility and regulatory controls.
The first step in development of a pre-injection treatment scheme is
characterization of the wastewater in terms of source, volume, and physical,
chemical, and biological characteristics as discussed in Chapter 5. Then,
if the waste is classified as suitable for injection, the necessary treat-
ment processes can be selected.
PLANT PROCESS CONTROL
An extremely important and often overlooked means of increasing the
feasibility of wastewater injection is modification of waste volume and/or
chemistry by control of the process by which the wastewater is produced.
In many industrial plants, particularly older ones, analysis of the
plant processes will show that changes can be made to reduce the quantity of
waste that is intended for injection. Perhaps the most easily made change
is segregation of wastes so that dilute streams of washwater, etc., are not
included in the injection stream. Major process changes may be possible for
the sole purpose of reducing waste volumes so as to match plant discharge to
available well receptivity. Also, the chemistry of a wastewater can some-
times be changed resulting in increased waste injectability. Such possibil-
188
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TABLE 6-1. OPERATIONAL PROBLEMS RELATED TO WASTEWATER
CHARACTER (OHIO RIVER VALLEY WATER SANITATION
COMMISSION, 1969)
PROBLEM OF CONCERN
REACTION
Wastes and
formation
'"IIi neral s
Wastes and
formation
wa te r
Autoreaction
of waste at
formation
temperature
and pressure
v'astes ana
system
components
MICROORGANISMS
s;.:snFN::'r:i SOL ins
AND OILS
MEANS OF EVALUATING
Laboratory tests
and observation
of system
Laboratory tests
Laboratory tests
Laboratory test:
and observation
of system
Laboratory tests
and observation
of system
Laboratory tests
and observation
of v/st.CY;
MEANS OF CONTROLLING
UNDESIRABLE EFFECTS
Pre-injection waste
treatment
Pre-injection waste
treatment or a buffer
zone
inhibitors to waste, and
jse cf corrosion-rein stant
materials
Pro-i n.u-M': t i on wtisfp t. nut-
rient and addition of bio-
•:ides
'"hf'f; i ca 1 'T ;•'!•( flan i ( a
do-Id'-, i f i r,i t, i or;
-------
ities should not be overlooked in the design of a new plant, because it may
be feasible to selectively segregate a wastewater for injection that cannot
be handled by other means and which would interfere with the treatment of
other plant wastes. Such planning optimizes the injection process.
TREATMENT PROCESSES
The types of pre-injection treatment used to achieve the desired goals
of a smooth, continuous, trouble-free operation are as varied as the geologic
conditions and wastewater properties that are encountered. The more impor-
tant basic pretreatment operations are listed in Table 6-2. The nature of
each type of operation will be examined in some detail. The complexity of
pre-injection treatment ranges from systems where only wastewater storage is
required before injection, as shown in Figure 6-1, to ones where an extensive
series of steps is required, as shown in Figure 6-2. The basic pretreatment
steps listed in Table 6-2 are not all necessarily used nor do they always
occur in the sequence given. For example, in Figure 6-2 addition of corrosion
inhibitors and storage are provided at both ends of the treatment sequence.
In addition to the basic pretreatment steps listed in Table 6-2, unusual
steps may be desirable in special instances such as distillation for recovery
of valuable volatile chemicals, biological treatment to break down certain
organic chemicals, or evaporation to reduce injection volumes.
Storage and Equalization
Wastewater streams may be produced in batches or they may be continuous-
ly produced. When waste is intermittently produced in batches, storage is
provided to allow pre-treatment and injection at the desired rate and to
equalize the chemical and physical properties of the wastewater. When wastes
are produced continuously, storage and equalization are beneficial in over-
coming extreme fluctuations in flow rate and wastewater chemistry. Detention
and mixing of several wastewater streams can result in chemical modifications
such as neutralization. Nemerow (1971) cites an example where a large chem-
ical corporation producing an acid waste provides storage for its waste for
a 24-hour period after which another nearby plant pumps its alkaline waste
into the holding basin, thereby neutralizing both wastes. Storage basins can
be used for settling of the largest suspended solids, if this is desired.
On the other hand, mechanical agitation can be used where settling of solids
is not desired.
As is shown in Figure 6-1, in the most simple systems, if the waste is
low in suspended solids and is non-corrosive, the collecting tank, transfer
pipes, injection pump, and controls may be the only required surface equip-
ment. This may also be the case where injection is into cavernous formations
that will accept untreated wastewater without danger of plugging. There are
even systems in which the injection pump is not needed, because wastewater
can be injected by gravity. Donaldson (1972) states that there are a few
such installations, but that they are not typical and additional equipment
is usually necessary.
190
-------
OIL
f f t r r r f<
• • • . • /
POND;
:.-.•:.•.•
* • " *
tflJJJlA
—
r;
.
OR BY GRAVITY
STORAGE,
SETTLING,
OIL REMOVAL
rrrrrr \\
S/S //t
/ ////
.. WELL
riGURr 6-1. SURFACE DESIGN FOR PRETREATMENT OF WASTES WHERE
ONLY STORAGE IS REQUIRED (SADOW, 1972).
-------
ro
pH
NHIBITOR
BRINE
COOL
NHIBITOR
i—STORAGE COAGULATION
SETTL ING
and Fl LTR AT ION
OIL SEPARATION 'VARIES'
SLUDGE
WEL L
SPARE
FIGURE 6-2. SURFACE DESIGN FOR PRETREATMENT OF WASTES WHERE
EXTENSIVE TREATMENT CLEANUP IS REQUIRED (SADOW,
1972).
-------
TABLE 6-2. BASIC PRETREATMENT STEPS AND THEIR OBJECTIVES
1. Storage and equalization - to allow an even flow
of wastewater to treatment facilities and/or in-
jection pumps and to permit equalization of waste-
water properties.
2. Oil separation - to remove liquid oils.
3. Suspended solids removal - to remove particulate
matter.
4. Chemical and biological treatment - to modify
wastewater chemistry and achieve compatibility
of wastewater with the injection system and in-
jection interval .
5. Corrosion and bacterial control - to reduce cor-
rosiveness and inhibit growth of microorganisms.
6. Degasification - to remove undesirable entrained
or dissolved gases.
-------
The design of a storage tank or basin is not complex, but it is so de-
pendent on the individual circumstances that general specifications cannot be
given. The following are some design guidelines suggested by Nemerow (1971).
The size and shape of tanks or basins vary with the quantity of wastewater and
the pattern of its discharge. When equalization is desired, capacity should
be adequate to hold, and render homogeneous, all the waste streams that are
to be equalized. If a cycle of plant operations is two hours, then a tank
that can hold a two-hour flow will usually be sufficient. If a cycle is re-
peated only each 24 hours, then storage for at least a 24-hour flow will be
required. It may be desired to hold and equalize several cycles of flow. In
any case, the holding capacity is related to the volume of wastewater produced
and the length of plant cycle.
The mere holding of waste, however, is not sufficient to equalize it.
Each unit volume of waste discharged must be adequately mixed with other unit
volumes of waste discharged many hours previously. This mixing may be brought
about in the following ways:
(1) proper distribution and baffling;
(2) mechanical agitation;
(3) aeration; and
(4) combinations of all three
These possibilities are expanded upon by Nemerow (op. cit.).
Oil Separation
The presence of oil in a wastewater is undesirable because it can cause
permeability reduction in sands or sandstones. Also, the presence of even
minute quantities of oil causes fouling of surface and subsurface equipment,
particularly filters. There are four common mechanical methods for oil re-
moval. These are: gravity separation, flotation, coagulation and sedimen-
tation, and filtration.
Gravity Separation --
In gravity separation, the oil and water mixture is allowed to separate
into two phases, with the lighter oil phase rising to the surface of the
heavier water phase. Gravity separation of oil can be achieved in open ba-
sins or tanks with an appropriate means of skimming off the oil or specially
designed oil-water separators can be used. The design of oil-water separa-
tors is covered in detail by the American Petroleum Institute (1969). Fig-
ure 6-3 shows one example of an API oil-water separator.
Gravity separation is highly effective with low specific gravity oils
that are not emulsified, but is less effective or impossible with high spe-
cific gravity oils and with emulsions. The probability of success of gra-
vity separation can be judged by a test described in API Method 734: Deter-
mination of Susceptibility to Oil Separation (American Petroleum Institute,
194
-------
• ^l< L- vpRTING I I OWS
'.( * :)'.i
V.
-------
1953). The commonly cited disadvantages of gravity separation are discussed
by Ingersoll (1951) and by the American Petroleum Institute (1951 and 1969).
Removal of small amounts of oil that remain after gravity separation
or that may be initially present in some wastewaters can be accomplished by
flotation, coagulation and sedimentation, or filtration (American Petroleum
Institute, 1969).
Flotation --
Pressure flotation is a process in which the wastewater is saturated
with air under pressure and then passed into a flotation chamber at atmos-
pheric pressure. Under reduced pressure, the air is released from solution
as small bubbles that carry the oil globules to the surface, where they are
skimmed off. Figure 6-4 is a schematic diagram of an air-flotation oil re-
moval process. Gases other than air may be used to avoid saturating the
wastewater with corrosive oxygen. Another form of flotation is vacuum flo-
tation in which air is introduced by mechanical agitation or air injection
and a vacuum is then applied to produce bubbles and cause flotation. Flo-
tation is effective for wastewaters containing less than 100 parts per mil-
lion of oil and where emulsions do not exist (Wright and Davies, 1966).
Wright and Davies (1966) list some disadvantages of flotation for oil
removal as:
1.
2.
3.
Emulsions are seldom resolved
Suspended solids may interfere with oil removal
The process is very sensitive to process variables
such as:
a. The flow volume through the system
b. The gas/wastewater ratio
Emulsions and Other Methods for Removing Oils --
Because, as has been pointed out above, emulsions seriously interfere
with oil removal, the properties of emulsions and methods of dealing with
them will be briefly explored. An emulsion can be found when oil and water
are mixed together under agitated conditions. The emulsion is, in fact,
the dispersion of finely divided droplets of one liquid into another liquid
medium. Depending on the relative quantity of the two liquids, either oil-
in-water or water-in-oil emulsion can be found. To make the emulsion stable,
a third substance, called an emulsifying agent, is required. Common emulsi-
fying agents include soaps, sulfated oils and alcohols, sulfonated aliphatics
and aromatics, quaternary ammonium compounds, non-ionic organic ethers and
esters, and various solids. Emulsifying agents enhance the strength of the
interfacial film around the droplets of the dispersed liquid by providing
layers of electrical charges, thus increasing the stability of emulsions.
Stability is created because the finely divided droplets are prevented from
coalescing into large droplets.
196
-------
OILY
SCUM
AIR
1
FLOCCULATING
AGENT
UP REQUIRED)
i
FLOTATION
CHAMBER
CLARIFIED
EFFLUENT
PRESSURE
RETENTION
TANK
FIGURE 6-4. SCHEMATIC DIAGRAM OF A FULL-FLOW AIR-
FLOTATION OIL REMOVAL PROCESS (AMERICAN
PETROLEUM INSTITUTE, 1969, P. 9-10).
-------
Emulsions can be broken by several different methods. Heat is helpful
in nearly all emulsion-breaking operations. Heating water-in-oil emulsions
lowers the viscosity of the oil and promotes settling of free water. Heating
also increases the vapor pressure of the water and tends to break the films
around the globule. Separation of the oil and water phases may be facilitated
by using caustic soda to adjust the pH between 9 and 9.5. Distillation is an
effective method of breaking emulsions and offers the advantage of separating
the water and light oil from the emulsifying agent which remains in the resi-
due.
Emulsions can be broken by chemical methods which vary according to the
properties of the emulsions. Perhaps the most widely used chemical method
is flocculation or coagulation. The two terms are frequently used inter-
changeably to describe the treatment process in which chemicals and other
additives are used to produce finely divided precipitates or microflocs.
These small particles then agglomerate into larger clumps that are more read-
ily removed. A wide variety of coagulants and coagulant aids are used. The
more common ones are listed by the American Petroleum Institute (Table 6-3A)
along with a jar test used for their selection and dosage determination (Amer-
ican Petroleum Institute, 1969, p. 9-18).
According to the American Petroleum Institute (1969), dissolved-air
flotation in combination with coagulation can reduce oil content to levels
approaching oil solubility. Further details of oil removal by this process
are given by the API (1969).
After coagulation, oil can alternatively be removed by sedimentation,
if the floes are dense enough to settle. However, oils will usually float
as opposed to suspended solids, which will usually sink. Sedimentation and
the fourth oil removal process, filtration, are discussed in the next section
concerning solids removal.
Suspended Solids Removal
Processes for suspended solids removal include sedimentation, flota-
tion, and/or filtration, and these processes in combination with coagulation.
Sedimentation --
Sedimentation is the process of removal of solids from water by gravity
settling. It is used when large amounts of suspended solids are present in
order to reduce the load on filters or, in cases where cavernous or fracture
porosity is present, sedimentation alone may be sufficient. Sedimentation
may be accomplished in basins or tanks. Basins can range in sophistication
from unlined earthen ponds to lined concrete basins. According to Nemorow
(1971), in recent years, design engineers have been using either circular
or square tanks instead of more conventional rectangular basins, for reasons
of space and/or economics. Most tanks are of standard commercial design and
an appropriate one can be selected by consultation with representatives of
companies that supply pollution control and water treatment systems. If a
special design or construction material is required, this can be arranged for
also. Sedimentation basins are tailored for each specific site and waste-
198
-------
water problem, but are often designed on the basis of existing installations
handling the same or a similar wastewater. Design of sedimentation basins
is covered in textbooks on industrial waste treatment and water treatment
(American Water Works Assoc., 1971; Nemcrow, 1971; Ross, 1968; Ostroff, 1965;
Eckenfelder. 1966; Gurnham, 1955), When both solids and oils are present;
the solids will usually sink and the oils float. Thus, both can be removed
in a sedimentation basin or tank which is designed for withdrawal of sludge
from the bottom and skimming of scum from the top (Figure 6-5). If possible,
however, it may be preferable to prevent mixing of waste streams containing
oil with ones containing suspended solids because removal of oil and solids
separately may be more readily accomplished. Dilution and formation of emul-
sions is also avoided (Gurnham, 1955).
Flotation --
Flotation, which was discussed under oil removal, is also used for
solids removal. Application is most likely to wastewaters containing small
difficult-to-settle particles or to oily wastes. Flotation is also possible
as an addition to sedimentation, rather than an alternative.
Filtration --
Filtration is the mechanical separation of suspended solids (or oils)
from wastewater by passing it through a porous medium that retains the solids
(or oils) on its upstream face or in the body of the filter. The wastewater
is forced through the filter by gravity, fluid pressure, or a vacuum. Oper-
ation of a filter at a constant flow rate requires continually increasing
pressure or fluid head to maintain the rate. When the maximum allowable
operating pressure is reached, filters are backwashed or otherwise cleaned
to renew them. Filters can also be operated at constant pressure, in which
case the flow rate will decline with time until maintenance is required.
The porous body which retains the suspended solids is the filter medium.
Common filter media include beds of granular particles such as sand or anthra-
cite coal, and cloth, plastic, or metallic screens. Screens may be coated
with filter aids to improve their performance. Diatomaceous earth is the
most commonly used filter aid. The filter aid increases the efficiency of
solids removal and is replaced when it becomes clogged. Other less common
filter media are straw, hemp, glass cloth, paper, wool, and rubber (Ostroff,
1965). Straw is mentioned in many references as being effective in filtering
oil that is not removed by separation.
Slow Sand Filters — Filters comprised of beds of granular particles arc
often classified as slow or rapid sand filters. As the name implies, the
velocity of flow through slow sand filters is very low (• 0.? gpn/ft'). To
oomponsato for this, the filter area must be large. Water is passed by gra-
vity downward through 1 -' to IH inches of oraded sand deposited on a base of
•'.jradea otMvel. I i 1 lered water is removed by underdraiMS. Because of their
inflexibility and the large area required, these filters are not popular for
ore-i T!.joe t ion treatment systems and will not be discussed further.
-------
Influent
n /-Baffle ..... .
—Jd f /-Liquid level
I Q"""
O
CD
Overflow weir
Scum trough-^
Collector flights
(moving scum)
Collector flights
(moving sludge)
Sludge drawoff
X
Effluent
FIGURE 6-5. SCHEMATIC DIAGRAM OF A SEDIMENTATION TANK
EQUIPPED FOR REMOVAL OF BOTH SLUDGE AND
SCUM (GURNHAM, 1955, P. 137).
-------
Rapid Sand Filters--Rapid sand filters are subdivided into gravity ra-
pid sand filters and pressure sand filters. Gravity rapid sand filters are
similar to the slow sand filters described above. They are composed of a
bed several feet thick that is generally deposited as several layers of vary-
ing grain sizes, with fine sand at the top and gravel at the base. Anthra-
cite coal of varying particle size is also used as a filter medium. Typical
specifications for the media of a gravity rapid sand filter are given in
Table 6-3, and a cross-sectional diagram is shown in Figure 6-6.
The rate of flow through a gravity rapid sand filter depends on the
size, grading, and depth of sand, type and efficiency of pre-filtration treat-
ment, and the required quality of effluent. A typical rate is 2 gal/min per
square foot of filter area, but higher rates are possible. The two general
schemes for control of filter operation are rate-of-flow control and loss-of-
head control. Since it will normally be desired to maintain a constant rate
of filtration, the rate-of-flow control system is most widely employed. In
this system, each filter is provided with controls that maintains a constant
flow rate through the filter. As time passes, the hydraulic head required
to maintain a constant flow rate increases, because the filter becomes clog-
ged with the solids removed from the treated water. When the head required
reaches a perdetermined maximum level, the filter is taken out of use and
cleaned. Cleaning is accomplished by backwashing and, in some cases, surface
washing. After cleaning, filter effluent is generally recycled for a few
minutes to allow the bed to settle and filtrate quality to stabilize.
Rapid sand filters can be equipped for manual operation, push button
operation, or fully automatic operation. In automatic operation, cleaning
of the filter (backwashing and surface washing, if used), recycling, and re-
turn to service are automatically carried out, when needed.
According to Ostroff (1965), pressure sand filters are more widely used
in industrial applications and in the oil fields than are any other types of
filters. Pressure sand filters are based on the same principles as the gra-
vity-feed rapid sand filter, except that the filter media and under-drain
system are placed in a cylindrical tank, and the water is passed through the
filter under pressure. This has the advantage that the filtered water can
be moved without additional pumping.
The position of the pressure filter tank may be either vertical or hori-
zontal. For areas up to 80 sn. ft. of filtering surface, the filters are
usually the vertical type; for larger areas, the horizontal type. Typical
vertical and horizontal pressure sand filters are shown in figures 6-/a an>'
5-7b. The horizontal type is generally about 8 ft,, in diameter am.1
i r. lennth fro;:; 10 Lc 25 ft. Vertical units ramie fror: i l.o I;' ''.
"Pier. Filter niedia for use in pressure sand filf.fr'.". .ire sirnlar '
siit'wr, in ri!-ie ' - •'• for <;r;iVM.v rs>;r;d sand ''liters.
-------
TABLE 6-3. TYPICAL SPECIFICATIONS FOR FILTER MEDIA
USED IN A GRAVITY-FEED RAPID SAND FILTER
(THE PERMUTIT COMPANY, 1954).
48" Sand & Gravel
48" Anthrafilt
5" of 1 1/2" x 1" gravel
5" of 1" x 1/2" gravel
4" of 1/2" x 1/4" gravel
4" of 3/8" x 3/32" gravel
6" of coarse sand, 0.8 to 1.2 mm
effective size
24" of fine sand, 0.4 to 0.5 mm
effective size
5" of No. 6 size 1 5/8" x 13/16"
5" of No. 5 size 13/16" x 9/16"
4" of No. 4 size 9/16" x 5/16"
4" of No. 3 size 5/16" x 3/16"
6" of No. 2 size 3/16" x 3/32"
24" of No. 1 size 0.55 to 0.65 mm
effective size
The uniformity coefficient of the
sand shall not exceed 1.6. The
sand must be round or angular,'
graded dry, and be practically
pure silica, free from appre-
ciable quantities of foreign
material. The gravel shall
consist of hard rounded pebbles,
containing not more than 2% by
weight of thin, flat, or elonga-
ted pieces, determined by hand-
picking, and free of shale, sand,
clay, loam, or organic impuri-
ties.
The uniformity coefficient of the No.
1 anthracite shall not exceed 1.6.
The anthracite shall consist of
hard and durable grains, having a
hardness of from 3 to 3.75 on the
Moh scale; specific gravity approxi-
mately 1.57; shall be free from iron
sulfides, clay, shale, or extraneous
dirt; and not more than ~\% shall con-
sist of dust.
202
-------
RATE OF FLOW &
LOSS OF HE AD GAUGES
OPfRATIMG
WAS"' WATER
FILTER INLET HEADER
^ADJUSTABLE WEIR EDGE
STEEL WASH TROUGH
CON'SOLLER
R ATE OF FtOW A LOSS'
Łf*Y FLOOR,
-ROTARY SURFACE WASHER'
GAST IRON MANIFOLD
FILTER TO WASTE
WASH OUT LEI
HEADER
LATERALS
CLEARWELL
:GURE 6-6. CROSS SECTION OF A CONCRETE GRAVITY RAPID
SAND FILTER (THE PERMUTIT COMPANY, 1954).
-------
Manhole
Inlet baflfl<
Raw water
inlet
filtered water
outlet
Fine sand
Coarse sand
Rinse waste line
Butterfly Valve
Sump —
Graded gravel
Concrete subfill
Header lateral
strainer system
Adjustable jack legs
Backwash waste line
FIGURE 6-7 (a). TYPICAL VERTICAL PRESSURE SAND FILTERS
(THE PERMUTIT CO., 1954).
-------
Raw water inlet--
Manhole
Header distributor
Concrete subrill
::>ump
Filtered
water outlet
Fine sand
Coarse sand
Graded gravel
Header lateral strainer system
with expansible strainer heads
FIGURE 6-7 (b) TYPICAL HORIZONTAL PRESSURE SAND FILTERS
(THE PERMUTIT CO., 1954).
-------
Pressure filters offer some advantages over gravity filters. Since
they have a higher capacity, pressure filters require less area. Pressure
filters also have an advantage where only one pumping of the water is de-
sired. One disadvantage is that the sand bed is not visible, so that the
operator cannot observe its condition and see if the backwash is functioning
properly. It is also more difficult to clean and replace the filter media or
to observe the filtered water.
Diatomite Filters—Of the remaining types of filters, diatomite or dia-
tomaceous earth filters are the most widely mentioned for water and waste-
water filtration. The filter is a porous screen, cloth, or other porous
septum upon which a thin layer of the diatomaceous earth or diatomaceous
earth-asbestos fiber medium is deposited prior to the beginning of filtration.
This layer, generally about 1/8 inch thick, is called the precoat. It is
applied by passing a slurry of diatomaceous earth and water through the fil-
ter until a sufficient coating has been deposited and the effluent is clear.
After deposition of the precoat, filtration begins.
Diatomite filters are either pressure or vacuum type (Figure 6-8).
According to Bauman (1971) the pressure filter theoretically is more useful
than the vacuum filter, since it can be designed to operate at any terminal
pressure drop. Practically, however, the pressure housing inherent to the
system makes it difficult to observe the effectiveness of the various filter
operations and increases the cost of maintenance in repairing or replacing
filter elements. The vacuum filter, though limited to 20 to 24 ft. of ter-
minal pressure drop across the filter, is much easier to operate and main-
tain. Vacuum filters will normally be used with clearer waters, and pressure
filters with more turbid waters.
Normally, diatomaceous earth filtration requires continuous addition
of filter aid into the waste stream by means of a slurry feeder following the
precoat step. This "body feed" builds up on the filter throughout the period
of filtration and maintains the porosity of the filter cake. The amount of
diatomite added to the raw water varies with the nature and quantity of solids
to be removed and with operating characteristics of the system. In some in-
stances, where the suspended solids content is low, the body feed can be omit-
ted. There are various grades of commercially available diatomite filter
media, which range in particle size and permeability (Dillingham and Baumann,
1964). The grade selected would ideally be that which would have the maximum
permeability and still provide the required degree of filtration.
When the differential pressure across the filter reaches the maximum
allowable, filtering is stopped, and the filter cake is washed from the sep-
tum, then a new precoat layer is deposited and filtration resumed.
Diatomite filters, like rapid sand filters, have the advantages of high
flow rates and low space requirements. In addition, they can deliver a very
high quality water. Wright and Davies (1966) reported routinely obtaining
a filtered water with 0.2 ppm suspended solids while using a diatomite fil-
ter. For this latter reason, diatomite filters have been frequently selected
for pretreatment of wastewater before injection.
206
-------
Max. pressure
differential
unlimited
T
i
Filter
pressure greater
than atmospheric
Source
of water
o
Pump
(a)
Filtered
water
oource
of water
'ess
Max. pressure
different IG I
18 - 22 ft
-------
At the same time, diatomite filters pose a dangerous potential for
plugging of injection wells when improperly operated. Wright and Davies
(1966) listed some of the causes of filter failure and resulting well plugging
as:
a. Plant operator leaves open line to high pressure pumps when back
washing and recoating filter. Large amounts of asbestos and dia-
tomaceous earth are injected into the well.
b. The filter cake and precoat drop off the screen in whole or in
part, due to temporary shut down of filter or to a momentary
pressure surge. Subsequent operation of filter results in all
slurry feed and all suspended solids going through the filter
into the high pressure pumps and/or into the wells.
c. Inadequate precoating of the screens has left holes in the pre-
coating, resulting in the same condition as Item "b" but to a
lesser degree.
d. Operator leaves backwash valve open partially or completely
after backwashing filter, resulting in partial or complete
bypassing of the filter. This is worse than no filter at all,
as in addition to bypassing the filter, filter aid is supplied
continuously to the water.
Filler Controls and Design—Because such incidents as mentioned above
cannot be entirely precluded, safeguards should be installed to prevent acci-
dental injection of solids or sludge. The pre-injection treatment system
should be designed for automatic recycle of treated water or shutdown of the
system in the event that an excess amount of suspended solids is present in
the injection water. This can be done by passing the treated water through
a continuous monitoring turbidimeter that is equipped with the desired con-
trols. Baumann (1971) notes that there are a number of continuous-flow
light-scattering microphotometers available, some of which are sensitive to
0.001 jackson units of turbidity (- 0.001 mg/1 suspended solids) and accurate
to 0.005 jackson units. Another precaution that can be taken is the instal-
lation of a back-up filter, perhaps an in-line cartridge type filter, in the
system as a final treatment device before injection. Such a filter is not
intended to perform routine removal of suspended solids, but to insure that
no excess solids reach the well. These two precautions should be considered
for all systems in which filtration is an important step, not just those that
use diatomite filters.
As with sedimentation tanks, many companies manufacture filters and fil-
ter controls and an appropriate filter system design can be obtained by con-
sultation with representatives of such companies.
Coagulation --
A discussion of coagulation was presented in the section concerning oil
removal, but some additional explanation is needed at this point. The pur-
pose of coagulation in suspended solids removal is to promote the formation
208
-------
of clumps or floes of suspended solids by agglomeration of smaller particles.
Coagulation is frequently needed before sedimentation and/or filtration to
promote the effectiveness of these processes.
The most commonly used coagulants are compounds of iron or aluminum
(Table 6-3A). According to Ostroff (1965), iron floes are usually denser and
more rapidly and completely precipitated than are aluminum floes. However,
aluminum compounds are better coagulants for waters containing appreciable
organic material. Jar tests (Ostroff, 1965; American Petroleum Institute,
1969) are recommended for determination of the proper coagulant and the opti-
mum concentration.
Coagulant aids must sometimes be added in addition to the coagulant to
obtain the desired flocculation. A few coagulant aids are listed in Table
6-3A. Not listed in the table are polyelectrolytes or polymeric floccu-
lents, which have become important in water and wastewater treatment (Cohen
and Hannah, 1971; Nemerow, 1971; Ostroff, 1965). In addition to coagulants
and coagulant aids, pH adjustment may assist the coagulation process. Accor-
ding to Cohen and Hannah (1971) iron and aluminum salts have been shown to
precipitate and coagulate most rapidly and with minimum solubility in some
characteristic pH range. The optimum pH and effectiveness of various coagu-
lant aids are investigated by jar tests. When coagulants are added, a mixing
tank or basin is conventionally used ahead of the sedimentation tank or basin.
Chemical and_Bio1ogical Treatment
Although subsurface injection is usually thought of as an alternative
to surface treatment, certain chemical or biological treatment steps may be
desirable or necessary. For example, it may be decided to neutralize an acid-
ic or basic wastewater to reduce its corrosiveness, rather than to construct
a corrosion-resistant system. Adjustment of pH in this case is for an entire-
ly different purpose than in the coagulation step previously discussed; how-
ever, both purposes could be served in an appropriate situation.
Common chemicals that may be considered for wastewater neutralization
are listed in Table 6-4. Dosage rates for acid and alkali neutralization
are shown in Tables 6-5 and 6-6. Limestone or lime slurries have a tendency
to form sludges of insoluble sulfates and reaction rates are slow. They are,
however, useful in some cases (Larsen, 1967). Soda ash, which is more expen-
sive, generally does not create excessive sludge; however, carbon dioxide
is a reaction product. Caustic soda, the most expensive of the common alka-
lis, reacts almost instaneously and creates less sludge. It also can be fed
at higher concentrations than soda ash or line, allowing compact feed equip-
ment.
Sulfuric acid is r:ost often used for neutra 1 i / im; alkalis. Although it
i<:. highly corrosive when diluted, "iuifuric ..icid c..;n be stored cit high con-
cent rations in carhop st.f'el r')rt<"i i n sulfur it' , "'.ore corrosive 'ind nore volatile. !'
!'v. y ',;si:!':,P :i ti"'f>'•> piier i r corrosr..Hi ^rni) I e:'"v *' Kr i k^1/, 1 ;b'" ' .
-------
TABLE 6-3A. SOME CHEMICAL COMPOUNDS USED AS COAGULANTS AND COAGULANT
AIDS (AMERICAN PETROLEUM INSTITUTE, 1969).
COMMERCIAL
COMPOUNDS FORMULA STRENGTH
Coagulants :
Al uminum sulfate A12(S04)3' 18H20 1 7 percent A1203
Sodium aluminate Na2Al204 55 percent Alg03
Ammonium alum Al 2(504)3(1^4)2505-24^0 11 percent A1203
Potash alum Al 2(S04)3- K2S04-24H20 11 percent A1203
Copperas FeS04'7H20 55 percent FeS04
GRADES
AVAILABLE
Lump
Powder
Granules
Crystals
Lump
Powder
Lump
Powder
Crystals
Granules
WEIGHT
(POUNDS
PER CUBIC
FOOT)
Powder:
38-45
Other:
57-67
50-60
60-68
64-68
63-66
SUITABLE
HANDLING
MATERIALS
Lead
Rubber
Sil icon
Iron
Iron
Steel
Rubber
Plastics
Lead
Rubber
Sil icon
Iron
Stoneware
Lead
Tin
Wood
REMARKS
Coagulation and sedimentation
systems; prior to pressure,
filters for removal of sus-
pended matter and oil.
Usually added with soda ash
to softeners.
Coagulation systems--
not widely used.
Coagulation systems--
not widely used.
Suitable coagulant only in
pH range of 8.5 to 11.0.
Chlorinated cop- FeS04'7H20+1/2C12 48 percent FeS04
.peras
Ferric Sulfate Fe2(S04)3
90 percent Fe2(SO)3 Powder 60-70
Granules
. . . Ferrous sulfate and chlorine
are fed separately.
Lead Coagulation—effective over
Rubber wide range of pH, 4.0 to
Stainless 11.0.
steel
Plastics
Ferric chlo- Fed 3~6H 0
ride hydrate
60 percent Fed Crystals
Rubber Coagulation—effective over
Glassware wide range of pH, 4.0 to
Stoneware 11.0.
-------
WEIGHT
(POUNDS
COMMERCIAL GRADES PER CUBIC
--Mr ::-'«'•': FORMULA STRENGTH AVAILABLE FOOT)
»i.-,> ,-.- • ;~ -.<-dc MqO 95 percent MgO Powder 25-35
--->•- j' a <•• ,". i .-K • *
[..f.r-_r-,r -• ... ... ... Powder 60
V,Hitr- silicate Na20( Si02 ) 3_25 40 B^ solution Solution 86
_•-.-, •.:••-•• t-.--i Ca'OH)? 93 percent Ca(OH)2 Powder 25-50
,-.:• • • ''a?c03 " Percent Na2C03 Powder 34-52
:.-.,-••- -:-:•-.! '.aQH 98 percent NaOH Flake . . .
Solid
Ground
Sol ut ion
SUITABLE
HANDLING
MATERIALS REMARKS
Iron Essentially insoluble--
Steel fed in slurry form.
Iron Essentially insoluble--
Steel fed in slurry form.
Iron . . .
Steel
Rubber
... pH adjustment and softening
... pH adjustment and softening
... pH adjustment, softening, o"
removal systems.
100 percent H2S04
Liquid
pH adjustment.
•-::;. *j>~ which no information is available, suitable as coagulant aids are activated silica, clay, activated
:i-::1zed starches, and ethyl cellulose.
-------
TABLE 6-4. COMMON CHEMICALS USED FOR WASTE NEUTRALIZATION (ANON., 1968)
Wastewater Character
Acid Wastes Alkaline Wastes
Lime Slurries Sulfuric Acid
Limestone Hydrochloric Acid
Soda Ash Carbon Dioxide
Caustic Soda Flue Gas
Ammonia Sulfur
Waste Alkali Waste Acid
TABLE 6-5. ALKALI REQUIREMENTS FOR ACID NEUTRALIZATIONS (ANON., 1968)
Alkali Source Approx. Dosage
(lb/lb H2S04)
Dolomitic Limestone 0.95
High Calcium Limestone 1.06
Dolomite Lime, Unslaked 0.53
High Calcium Limestone, Unslaked 0.60
Dolomitic Lime, Hydrated 0.65
High Calcium Lime, Hydrated 0.80
Anhydrous Ammonia 0.35
Soda Ash 1-10
Caustic Soda 0.80
TABLE 6-6. ACID REQUIREMENTS FOR ALKALI NEUTRALIZATIONS (ANON., 1968)
Acid Approx. Dosage
" (lb/lb CaC03)
H2S04, 66°Be 1.0
HC1, 20°Be 2.0
Flue Gas, 15% C02 3.0
Sulfur* 0.3
*The use of sulfur would produce a reducing condition which might require add-
itional treatment to produce an oxygen-containing effluent.
212
-------
Carbon dioxide and sulfur dioxide may be fed directly from bottles
into alkaline wastes, although this method is quite expensive and not used
frequently (Perry and Frank, 1966). Treatment with flue gas, if available
at the plant site is an alternative. Flue gas usually contains up to 14%
by volume of carbon dioxide and is in common use. In some situations, burning
sulfur to generate sulfur dioxide may be practical for neutralization. Ne-
merow (1971) devotes a short but well-written chapter to neutralization of in-
dustrial wastes.
Another chemical treatment step that might be desirable prior to in-
jection is removal of heavy metals. These might be removed for their value,
or they might be removed to prevent their precipitation after injection.
Neutralization will cause precipitation of many metals. Other possible re-
moval methods are ion exchange and oxidation or reduction. An example of a
system in which metal recovery is applied is Beale Air Force Base, California,
where silver is recovered by ion exchange before injection of a photo-pro-
cessing waste (Warner, 1972).
In some cases, chemical or biological oxidation of organic chemicals may
be employed to alter, reduce, or eliminate chemical or biological-oxygen de-
manding material. Such organic chemicals can be undesirable because they pro-
vide nutrients that support biological growth. Also, some organic chemicals
are extremely viscous and others are unstable and subject to polymerization;
both characteristics are undesirable in an injected wastewater.
In cases where a problem of incompatibility of injected and interstitial
formation water is anticipated, tne use of sequestering and chelating agents
may be more practical and economic than other possible solutions. For exam-
ple, when the wastewater contains a compound such as barium chloride and the
formation water an incompatible ion such as sulfate, the barium ion can be
'.;:)mpl exec; by adding a iequestering or cheiating agent. Ostroff (1965, p. K1-
90) provides a good review cf the chemicals used for this purpose ana their
applications. °recipitation of calcium, magnesium, barium, strontium, iron.
and other similar cations can also be prevented by exchanging these ions for
a soluble ion such as sodium or Dy Mme-soda ash water softening.
The forms of chemical and biological treatment mentioned are considered
the most "likely to be employed in pre-i n jectinn waste 'Codification; however,
others may occasionally be applicable. For further details of industrial
was lewdter treatment, textbooks on the subject can be consulted (Koziorowski
cind Kuchdrski, 1972; Nemerow, 1971; Ross, 1968; Eckenfe 1 der, 1966, Gurnhar;,
1955).
Corrosion iind Bacterial Control
f. xtremel v i^'.por t.
-------
Addition of chemical corrosion inhibitors to a water may provide a sim-
ple and inexpensive solution to a corrosion problem that otherwise might re-
quire use of expensive corrosion resistant materials or water treatment equip-
ment.
There are a wide variety of inorganic and organic compounds used as
corrosion inhibitors. The conditions of the environment and type of corrosion
govern the choice of inhibitor. Usually, the choice of inhibitor is based on
the experience of the corrosion engineer and some trial-and-error testing.
Some typical inorganic corrosion inhibitors are shown in Table 6-7, and typi-
cal organic corrosion inhibitors in Table 6-8.
Chemicals used to kill microorganisms are bactericides. Some inorganic
chemicals are used as bactericides, for example chlorine, chromates, and com-
pounds of mercury or silver. However, most currently used bactericides are
organic chemicals. Some typical chemicals used as bactericides are listed
in Table 6-9.
Brand-name bactericides contain one or more compounds of the type listed
in Table 6-9, in varying amounts, as the active ingredients. The amount of
active ingredient in a commercial bactericide determines its price and the
quantity necessary for bacterial control. Service companies that supply bac-
tericides for oil-field use should be consulted when selecting a preparation
for microbial control in an injection water.
Degasification
As discussed in Chapter 5, there are several common gases that may be
entrained or dissolved in a wastewater and which may be corrosive particular-
ly under higher pressure. These include oxygen, hydrogen sulfide, carbon
dioxide, and methane.
Methods of degasification include:
1. Aeration
2. Heating
3. Vacuum degasification
4. Chemical degasification
5. Counter-current scrubbing
Aeration is a useful method of removing gases such as carbon dioxide
and hydrogen sulfide. The difficulty with aeration is that the water becomes
saturated with atmospheric oxygen, which also is undesirable because of its
corrosivity.
Open heaters and closed deaerating heaters are used for removing oxygen
and carbon dioxide from boiler feed water, but have not been found mentioned
in connection with pre-injection water treatments.
214
-------
TABLE 6-7. TYPICAL INORGANIC CORROSION INHIBITORS (GATOS, 1956).
Inorganic Inhibitors
Borax
Cal gon
Di sodium hydrogen
phosphate
Potassium dichromate
Potassium di hydrogen
phosphate + sodium
nitrate
Potassium permanganate
Sodium benzoate
Sodium carbonate
Sodium chromate
Sodium chromate
Sodium dichromate
Sodium dichromate +
sodium nitrate
Sodium hexametaphosphate
Sodium metaphosphate
Sodium nitrite
Sodi urn ni tri te
Approximate
Cone. , %
2-3
small amount
0.5
0.05-0.2
small amount
+ 5%
0.10
0.5
smal 1 amount
>0.5
0.07
0.025
0.1 + 0.05
0.002
small amount
0.005
20: of sea
water
Corrosion
Environment
alcohol antifreeze
mixtures
water systems
citric acid
tap water
68-194°F
sea water
0.3N NaOh solution
0.03% NaCl solution
gas condensate
wells
cool ing water
CaCl? brine
water
water
water, about
pH = 6
ammonia
water
sea water- di sti 1 1 ed
water mixtures
Metallic
System
automobile
cooling system
steel
steel
iron-brass
steel
al uminum
mild steel
iron
electrical rec-
tifier systems
Cu . brass
air-condition-
ing equipment
heat-exchange
devices
lead
mild steel
condensers
mild steel
mild steel
Sodi urn orthophospha te
Sodi urn s i 1 i rate
Sodi urn r, i 1 ica ti>
1
smalI amount
f!. (..)!
water, pH 7.25
sea water
o i 1 f i el (i !>r i ne
i ron
An, An-AT
alloys
steel pipes
-------
TABLE 6-8. TYPICAL INORGANIC CORROSION INHIBITORS (GATOS, 1956).
Organic Inhibitor
Benzanil ide
Formaldehyde
Formal dehyde
Dioctyl ester of sulfo-
succinic acid
Erthritol
Ethyl am' line
Mercaptobenzothiazole
Morphol ine
Oleic acid
Phenyl acridine
Pyridine + phenylhydra-
zine
Quinol ine eth iodide
Rosin amine-ethylene
Approximate
Cone. , %
0.2
small amount
0.05
0.05
smal 1 amount
0.5
1
0.2
small amount
0.5
0.5 + 0.5
0.1
0.2
Corrosion
Environment
1 ubricants
oil wells
sour crude oil
refined petroleum
oils
i^SO^. solution
HC1 solutions
HC1 solutions
water
polyhydric alco-
hols
^$04 solutions
HC1 solutions
IN H2S04
HC1 solutions
Metallic
System
Cd-Ni, Cu-Pb
bearings
oil well
equipment
Diesel engines
pi pel ines
mild steel
ferrous metal s
iron and steel
heat-exchange
systems
iron
i ron
ferrous metals
steel
mild steel
oxide
Tetramethylarnmoni urn azide
ihiourea
0.5
aqueous solutions
or organic solvents
iron and steel
iron and steel
216
-------
TABLE 6-9. SOME TYPICAL CHEMICALS USED AS BAC-
TERICIDES (OSTROFF, 1965, P. 165).
Type of Chemical
Compound Example Name
Chromi urn
Mercury
Si 1 ver
Amine
Di amine
Quaternary
i 'o n n
AmmO rt i ijm I 0 , 13
Imidazol ines
Chlorinated
A 1 deh /des
Mercurials24
sodium chroma te
mercuric chloride
silver nitrate^
coco primary
amine acetate"'''''
coco trimethy-
lene di amine
alkyl trimethyl
quaternary ammo-
nium chloride
1 -phenyi -4 ,4-
di methyl ,-
imi dazol i ne ^
sodium tetrachlcr-
phena tef-2 >23
ql -jtc?ral dehyde
I'lethyl mer-
Concentration
Physical Range
Compound Formula Form (ppm)
Na?Cr04
HgCl2
AgN03
(R-NH3)+(CH3CO-0)-
C12H25-NH(CH2)3NH
RN(CH3)3C1
C3H5NCHNC(CH3)2CH2
NaOC3HCl4
C^H302
CHvicCOOOCHo
sol id
solid
sol id
sol id
1 iquid
liquid
sol id
sol id
1 i q u i d
sol id
500
50-300
0.05
10-40
5-25
25-- 100
75- -100
12-50
?o-;75
?5~1
-------
Wright and Davies (1966) list deaerating columns using vacuum deaeration
or counter-current gas scrubbing as the most feasible method for removing dis-
solved oxygen down to the level where the remainder can be removed by chemical
scavengers. According to Watkins (1958) disadvantages of vacuum deaeration
are that it is expensive, the mechanical removal of dissolved oxygen to a con-
centration of less than 1 ppm is difficult, and the removal of oxygen is usu-
ally accompanied by the removal of some free carbon dioxide. Carbon dioxide
removal changes the carbon dioxide-bicarbonate balance and promotes precipi-
tation of carbonates. The principals of counter-current gas scrubbing are
discussed by Crawford (1955).
All materials used in deaerating columns should be resistant to a cor-
rosive atmosphere. The shell of the columns should be lined with an epoxy
material, the trays and other internal equipment should be of stainless steel.
Deaerating columns can also serve a small capacity surge tanks between
the supply to the filtration equipment downstream and the discharge to the
injection pumps. Monitors and controls should be provided to throttle the
inlet or outlet and to maintain a liquid level within a predetermined range.
More than one deaerating column should be provided to facilitate service and
repair.
Industrial practice indicates that deaerators can reduce the dissolved
oxygen content to 0.5 ppm or less. With the addition of chemical scavengers,
the level can be reduced to 0.04 ppm or less, which results in effective cor-
rosion control (Blout and Snavely, 1969). Such systems are kept closed down-
stream of the deaeration equipment, which requires that all vessels such as
chemical mixing tanks, surge tanks, etc. be blanketed with an oxygen free,
inert gas.
Chemical methods used to remove a gas from water depend upon a reaction
between the gas and the chemical added to the water. This results in the
selective removal of a specific gas, rather than using degasification to re-
move all dissolved gases, as in vacuum deaeration. The most important appli-
cation of chemical degasification is for the removal of dissolved °xygen from
water.
All chemical methods used to remove dissolved oxygen from water are
based upon the reaction of oxygen with some easily oxidizable substance, the
most commonly used being sodium sulfite (Templeton et. al., 1963) and hydra-
zine (Leichester, 1956). These chemicals are particularly useful for remov-
ing the small amounts of oxygen that remain after one of the physical deaera-
tion processes.
INJECTION PUMPS
There are many different types of equipment available for the pumping
of liquids and for practical purposes they are divided into two distinctive
types: (1) kinetic and (2) positive displacement. These classifications can
be further broken down as illustrated in Table 6-10. The common types of
injection pumps are centrifugal, turbine, piston-type duplex and multiplex
plunger pumps. Centrifugal pumps have been used for low-pressure service
218
-------
TABLE 6-10. GENERAL PUMP CLASSIFICATIONS (CLARK AND GEDDES, 1972).
Positive ;
Displacement Kinetic
Reciprocating Rotary Regenerative Axial
Piston Diaphragm Vane Centrifugal
i
Plunger Gear Screw Mixed Flow
Increasing
Viscosity
-------
(<300 psi), but turbine and single-stage centrifugal (Anon., 1964) pumps cap-
able of operating at relatively high pressures are available (API, 1960).
Duplex piston-type pumps operate satisfactorily at pressures up to 500 psi,
and multiplex plunger pumps are adapted for higher pressures (Logan, 1956).
The pump types to the left of the center line are more suited to handle high-
viscosity liquids and high pressures (Clark and Geddes, 1972).
The most common type of pump used in disposal well systems is the cen-
trifugal type, but reciprocating units also find wide use (Hicks and Edwards,
1971). Centrifugal pumps usually have heavy casing walls which give corro-
sion protection. Design provisions are made to keep corrosive and often very
low pH or acidic liquids from exposure to the pump shaft. Provision for ser-
vicing of wearing parts is an important feature of all modern pumps.
The size, type and number of injection pumps is governed by:
(1) the well-head pressure,
(2j the volume of wastewater to be injected, and
(3) the variability of injection rates.
A few installations do not require an injection pump because the wastewater
in the well column exerts sufficient pressure at the subsurface face of the
formation to drive the fluid into the formation. If the well-head pressure
for waste injection is less than 150 psi, simple, single-stage centrifugal
pumps can be used, but at higher pressures, multiplex piston-type or multi-
stage centrifugal pumps are needed. Therefore, it may be necessary to delay
selection of an injection pump until the well is ready for operation and pump-
ing tests can be made.
EXAMPLES OF INTEGRATED TREATMENT FACILITY DESIGN
Many of the individual components and treatment processes used in the
surface facilities of injection systems have been described. However, it re-
mains to be shown how these are integrated into an overall pretreatment and
injection plant. This will be accomplished by the use of selected examples
for wastes with typical characteristics.
Detailed case histories of surface pre-injection treatment methods are
readily available in the literature. Paper industry surface-treatment appli-
cations in Pennsylvania are described by Brown and Spalding (1966); chemical
industry applications in Texas, Michigan and Alabama are reviewed by Veir
(1969); Henkel (1955), Klotzman and Veir (1966): Texas; Paradise (1955):
Michigan; Tucker and Kidd (1973): Alabama. Steel industry surface-treatment
applications are explored by Hartman (1966, 1968): Indiana; Smith (1969):
Ohio; nuclear-related applications are reported by Arlin (1962): New Mexico;
Halligan (1961): Colorado; Stage! and Stogner (1969): U. S. general.
The single most comprehensive review of a number of case histories in-
volving surface treatment can be found in the works by Donaldson, et. al.
(1974K Warner (1972), the U. S. Environmental Protection Agency (1974). and
220
-------
Reeder (1975) inventoried injection systems in the United States and, where
available, provided brief descriptions of the surface facilities of each sys-
tem.
Simnle Onen System
Figure 6-9 depicts the surface equipment used in the case of an acidic
waste that is not complicated with suspended solids or oilsJ Also, in this
case, the injection interval is a vugular limestone, a type of stratum that
will often accept a wastewater that has had little or no pretreatment.
Because of the high permeability of the injection interval, no injection
pump is needed and the absence of suspended solids precludes the need for
filtration. Only a collecting sump and a metering valve to regulate the flow
of waste into the well are required.
During normal operation, wastewater from various plant streams enters
the sump, which has a metering weir near the outlet end to measure the rate
of flow. A flow-control valve, regulated by a liquid-level meter in the out-
fall below the weir, is present to avoid sudden changes in the rate of flow
into the well that could cause serious water hammer or surging. When the
liquid level in the sump reaches a preset minimum, the control circuit closes
the valve and prevents air from entering the well. A steel-jacketed polyethy-
lene pipe is used to transport the wastewater from the control valve to the
well-head; the fluid pressure in this pipe is monitored. The oil tank is for
storage of light oil that is maintained under pressure in the annulus of the
well to support the fiberglass tubing and to detect tubing leaks. A break in
the tubing will cause an immediate change of pressure in the annulus which
will be recorded by the pressure monitoring equipment.
Semi-CpmpJex pj)e_n System
Figure 6-10 is a schematic drawing of the surface equipment used in han-
dling waste steel pickling liquor produced during the manufacture of steel.
One step in the final processing of steel is the removal of iron oxides from
the surface, just prior to cold rolling, by emersion in a solution of hydro-
chloric or sulfuric acid. The waste pickle liquor is the spent acid solution
containing 13 to 25 percent, iron by weight, principally as ferrous chlori'ie
."'r sulfjte. In the particular example sh'jwn, the wastewater is a ferrous
ine pret.rea tnien t system is only slightly '"ore co:;^ i e.x than fit1 first
example. The waste is <, oiieeted in a 35,000-na 1 1 i>n f
-------
Liquid level meter
Weir.
Valve controller
Pressure recorders
U
Collecting sump
Flow control
valve
Oil tank
-Well annulus
• Injection tubing
Injection
FIGURE 6-9. OPEN SURFACE EQUIPMENT USED IN A
SIMPLE WASTE-INJECTION SYSTEM
(DONALDSON, 1972).
-------
Precoatcd
Itaf filters
80-inch con-/ 35,000"
pickling lm« J gallon receiving]
tank
Lake water to
dilute waste
pickle I iquor
3- way
valve
r-00—Q-
-00-
L^x—^-
Magnetic
f lowmete r
To backup treatment syslem,
neutralizat ion plant
Annulus monitoring
f !u id , water with
biocide
well
FIGURE 6-10. SURFACE EQUIPMENT FOR HANDLING WASTE
HYDROCHLORIC ACID PICKLING LIQUOR
FROM A STEEL PLANT (DONALDSON, 1974).
-------
well that operates under gravity flow at 30 to 50 gpm injection rates. A
backup surface treatment neutralization plant is provided in the event of a
well shut-down.
In this system, wastewater is collected directly in a tank. In other
cases a sump may be used ahead of the tank. According to Bayazeed and Don-
aldson (1971), regardless of the method practiced, the gathering system is
constructed of acid-resistant materials. The sumps are generally constructed
of brick cemented with resin, and the gathering tanks are constructed of rub-
ber-coated steel. Transfer of waste pickle liquor is carried out with pipes
and centrifugal pumps having all wetted parts made of epoxy resins, Teflon,
or other acid-resistant materials.
Complex Open System (basic and acid wastes)
A relatively complex pre-injection treatment system is illustrated in
Figure 6-11. The principal wastewater in this instance is basic and contains
large amounts of suspended solids, some oil, and various inorganic and organ-
ic chemical sJ
The system was designed to treat the wastewater for injection into a
limestone with low permeability. In the collecting pond, the oil is skimmed
from the surface with an automatic skimmer that travels slowly across the
pond, and the skimmed oil is burned in an incinerator. The waste liquor is
then treated with coagulators to accelerate sedimentation of the suspended
solids and with waste hydrochloric acid for pH control. The sludge from the
coagulator and backwash of the filters is sent to a drying bed, and the under-
drain is returned to the collecting pond.
A series of four leaf filters is used to filter the effluent from the
coagulator, and the waste is then stored in a surge tank, The waste is pump-
ed by multistage centrifugal pumps into a manifold at an average 1,100 gpm
flow rate at 1,000 psi pressure (Veir, 1967).
Waste hydrochloric and nitric acid streams are collected in separate
tanks and pumped into the injection-pump manifold. The waste acids are col-
lected separately because the waste streams are not constant; whereas, if the
acids were added directly to the collecting pond, they would cause wide varia-
tions in the pH of the composite waste.
Complex Open System (organic acids)
The surface equipment for pre-injection treatment of an organic waste-
water is shown in Figure 6-12. The waste is an aqueous process waste solu-
tion containing approximately 5% (the percentage varies) water-soluble organ-
wastewater is a stream of containing NaHC03 (395 ppm); NaCl
(9,100 ppm); CaS04 (1,360 ppm); Mg S04 (1,500 ppm); NH3 (1,000 ppm); adipic
acid (1,500 ppm); soluble organics (1,000 ppm); pH = 8.5. Waste HC1 (6.0%)
and HN03 (4.0%) are added at the injection pump manifold (Donaldson, 1972).
224
-------
Waste HC
Waste HN03
Oil to rc.!rerator l& ]
Solids to land fill
iGURE 6-11. EXAMPLE OF A COMPLEX OPEN WASTEWATER
PRE-TRF:ATMENT SYSTEM FOR A MIXED
WASTE (DONALDSON, 1972).
-------
pH control
Waitt in
r-o
r-o
CT>
Pond 3
Aerator
©
Pond 2 ^*-S
Pond
Pumps
K>
Filters
-o
FIGURE
SURFACE PRE-INJECTION TREATMENT
SYSTEM FOR PREPARATION OF THE
WASTEWATER CHARACTERIZED IN
TABLE 6-11 (DONALDSON, 1974).
-------
ics after treatment. An analysis of a composite sample of the effluent being
injected is given in Table 6-11.
The waste being injected originates from the manufacture of a polymer
from acetylene and formaldehyde and is considered toxic. Pilot testing of
compatibility was conducted and indicated that by controlling pH and by fil-
tering, compatability could be achieved. The wastewater from the processing
units enters pond 1 where it is aerated to terminate the polymerization reac-
tion. The fluid is then discharged over a weir into pond 2 where it is treat-
ed with lime and aerated a second time. Pond 3 is a sedimentation pond equip-
ped with baffles. The waste is made slightly acidic (pH about 6.0) by auto-
matic equipment that controls a valve on a hydrochloric acid storage tank.
Some sludge-type organic material is precipitated in pond 3 and this is per-
iodically vacuumed by a service company for land disposal. Waste water from
pond 3 is filtered in an anthracite-sand pressure filter and stored in a 15-
foot-diameter by 20-foot high tank. Two single-stage centrifugal pumps are
connected in parallel for injection at the well. The injection rate ranges
from 100 to 150 gpm.
Complex Closed System
A somewhat complex system designed for the pretreatment of an acidic
wastewater containing volatile chlorinated hydrocarbons is shown in Figure
6-13. The wastewater is very low in pH, and contains hydrochloric acid, ace-
tic acid, chloroacetaldehydes, and chloroacetic acids. The presence of low-
boiling chlorinated hydrocarbons makes this a very reactive solution, which
is extremely irritating to mucous membranes and to skin. Therefore, the
waste is handled in a completely closed system.
The wastewater in the collection sump is not stable, forming polymers
that precipitate upon standing. At a pH greater than 5.0, a tar-like
polymer would be formed by condensation of the aldehydes. Therefore, the
wastewater is pumped from the sump to a mixing tank where sodium hydroxide
is used to stabilize the waste by increasing the pH from 2.5 to between 4.0
and 5.0.
Following pH control, the waste liquor is filtered in rack-type pressure
filters that are designed for backwash and precoat operation as completely
closed systems. The processed wastewater is stored in a surge tank equipped
with a liquid-level meter that controls the operation of the injection pump.
As a final precaution, just prior to injection into one or more wells, the
wastewater is passed through a cartridoe filter to remove any suspended so-
lids that may have accumulated or formed during retention in the surge tank.
Two single-stage centrifugal pumps connected in series are used to inject
the waste at an average flow rate of 3!>0 g:.im and average well-head pressure
of 400 ;>s-i .
Ihe selec' ion oi na for i a 1 s for i ens t.ru; t ion of the ssjrfate sire •! n \r; ' ; m
treatment system was a critical design i ons i dera t. i on hecauso the was t.ewa ter
is !.'>.'. rei:ie I y corrosive 1o standard cons' rut. ! ion materials. ! pox1,' ;>las!t:
i'ilie, Has to 11oy (', :! >.-, stainless s'oel, and titanium alloys were used where
r i •' ]iri t' e'!.
-------
TABLE 6-11. ANALYSIS OF AN ORGANIC WASTEWATER TREATED IN
THE SURFACE SYSTEM SHOWN IN FIGURE 6-12
(DONALDSON, 1974).
Component Concentration, ppm
Sodium hydroxide 1,297
Sulfuric acid 2,397
Hydrochloric acid 25.
Acetylene 96.
Formaldehyde 500
Propargyl alcohol 499
Methanol 2,305
Benzene 420
Butyl alcohol 92.
Butanediol 918
Butyrolacetone 425
Tetrahydrofuran 518
Butyric acid 11
Ammonia 2,642
Pyrrolidone 268
Vinyl pryrrolidone 498
C-2's 122
Light ends 104
Gunk 114
228
-------
pH Control
COuS'iC
Storage
Treated water
to annulus
AŁ±±
Waste
Mixing
tank
Filters
Surge
tank
Injection ''
pump
Filler
Well No.I Well No 2
bump
. r.LOSFD SURrACE PRE-INJECTION EQUIPMENT USED FOR A WASTE CONTAINING VOLATILE ORGANIC
COMPONENTS (DONALDSON, 1972).
-------
REFERENCES
CHAPTER 6
Anonymous. "Single-Stage Centrifugal Pump Gives Big Boost in Pressure."
Oil & Gas Journal. Vol. 74. August 10, 1964.
Anonymous. "Water Pollution Control." Chemical Engineering Deskbook on
Environmental Engineering. October 14, 1968.
American Petroleum Institute. Investigation of the Behavior of Oil-Water
Mixtures in Separators. API, New York. 1951.
American Petroleum Institute. Determination of Susceptibility of Oil to
Separation. API Method 734-43. API, New York. 1953. 1 p.
American Petroleum Institute. Subsurface Salt Water Disposal. Div. Produc-
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American Petroleum Institute. Manual on Disposal of Refinery Wastes. Vol-
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First Edition. API, New York. 1969.
American Water VJorks Association. Water Quality and Treatment. 3rd Edition.
McGraw-Hill Book Co., New York. 1971.
Arlin, Z. E. "Deep Well Disposal of Uranium Tailing Water." in 2nd Confer-
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1961. J. M. Morgan et. al., eds. U. S. Atomic Energy Commission Rept.
TID-7628. 1962. pp. 356-362.
Baumann, E. R. "Diatomite Filtration of Potable Water." in Water Quality and
Treatment. McGraw-Hill Book Co. 1971. pp. 280-294.
Bayazeed, A. F., and Donaldson, E. D. "Deep-Well Disposal of Steel Pickling
Acid." Society of Petroleum Engineers Paper. Number SPE 3615. 1971.
Blout, F. E., and Snavely, E. S. "Use of Oxygen Meter in Corrosion Control."
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Paper No. 44. 1969.
Brown, R. W., and Spalding, C. W. "Deep Well Disposal of Spent Hardwood
Pulping Liquors." Water Pollution Control Fed. Vol. 38, No. 12.
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230
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Clark, R. A., and Geddes, G. "Which Pump?" Engineering. November, 1972.
pp. 1089-1092.
Cohen, J. M., and Hannah, S. A. "Coagulation and Flocculation." in Hater
Quality and Treatment. McGraw Hill Book Co. New York. 1971. pp. 66-
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Crawford, P. B. "Aeration with Combustion Gases." Producers Monthly.
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Dillingham, J. H., and Baumann, E. R. "Hydraulic and Particle Size Character-
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Donaldson, E. C. "Injection Wells and Operations Today." Underground Waste
Management and Environmental Implications. AAPG Memoir 18. 1972.
pp. 24-26.
Donaldson, E. C., et. al. "Subsurface Waste Injection in the United States --
Fifteen Case Histories." U.S. Bureau Mines I. C. 8636. 1974. 72 pp.
Eckenfelder, W. W. Industrial Water Pollution Control. McGraw-Hill Book Co.
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Gratos, H. C. "Inhibition of Metallic Corrosion in Aqueous Media." Corro-
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Gurnham, C. F. Principles of Industrial Waste Treatment. John Wiley and
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Halligan, E. G. "Deep Well Fluid Waste Disposal." in 2nd Conference on
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Gan, et. al. TedsTJ. U.S. Atomic Energy Commission Rept. TID-7628.
1961. pp. 368-375.
Hartman, C. D. "Deep-Well Waste Disposal at Midwest Steel." Ij"pn Uld_.._S_t_eeJ_
Engineering. December, 1966. pp. 118-121.
Hartman, C. D. "Deep-Well Waste Disposal of Steel-Mill Wastes." Jj?jy/_naj[
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Henkel , H. 0. "Deep Well Disposal of Chemical Wastes." Chemical Engineering
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Inqprso'll, A. C. "The Fundamentals and Performance of Gr.wity Separation, A
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Klotzman, M., and Veir, B. "Celanese Chemical Pumps Wastes Into Disposal
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Krikau, F. G. "Neutralization is the Key to Acid-Liquor Waste Disposal."
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Slagle, K. A., and Stogner, J. M. "Oil Fields Yield New Deep Well Disposal
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-------
CHAPTER 7
INJECTION WELL DESIGN AND CONSTRUCTION
After the suitability of a possible injection well site has been con-
firmed regionally and locally, and the suitability of the wastewater to be
injected has been determined, it is appropriate to develop a well design and
construction program. Since the well is such an important part of the injec-
tion system, its proper design and construction are obviously fundamental to
the success of the injection program. As has been found by experience, minor
mistakes in design or construction can result in damage to the well and sub-
sequent economic loss and possible degradation of the environment. The most
common deficiency in well design has been inadequate provision for corrosion
protection. In construction an oversight as small as improper selection of
the drilling fluid used while drilling the injection interval can result in
irreversible loss of permeability and possibly even in well abandonment.
PLANNING A WELL
The first step in planning a well is the acquisition of geologic and
engineering information for the well site and for any previously constructed
wells in the area. Determination of the geologic and engineering character-
istics of the site will have been accomplished during the regional and local
site evaluation. These characteristics must now be evaluated in view of their
significance to well design and construction. Local experience in well design
and construction is an invaluable aid in planning a well and the importance
of obtaining information concerning local design and construction practices
cannot be overemphasized.
Projected Geological and Engineering Conditions
Prior to the initiation of the well design phase, geological and engi-
neering conditions will have been considered with regard to the feasibility
of injecting the wastewater of concern and with regard to the environmental
suitability of the site. The well designer must now consider how to match
the well design and construction procedures to the expected conditions.
Briefly, the designer should know the anticipated maximum total well
depth; the lithologic sequence to be penetrated; the anticipated location,
thickness, and lithology of possible injection and confining intervals; the
location of fresh-water-bearing aquifers; and the location of any possible
mineral resources. These site characteristics are obtained in the ways pre-
viously discussed in Chapter 3.
234
-------
Previous Drilling Experience
The designer should take maximum advantage of information concerning
wells previously drilled in the area. Such information includes bit records,
drilling mud records; casing and cementing programs, and the driller's logs
and drilling-time logs that are discussed in Chapter 3. Moore (1974) explains
the nature and value of these various sources of information in some detail.
One of the items sought in the records of previous wells is the exis-
tence of any drilling hazards. Drilling hazards include lost circulation
zones, zones of abnormal hole enlargement and sloughing and zones in which
hole deviation or pipe sticking are problems. In an area where no wells have
previously been drilled, the possibility of such hazards must be inferred
from the projected subsurface geologic conditions.
Completion Method
A major decision that is made early in the planning of a well is the
choice of the bottom-hole completion method. When considered in detail, a
wide variety of bottom-hole completion methods are used, but in general they
can be categorized as methods applied to wells completed in competent forma-
tions and methods applied to wells completed in incompetent formations. Com-
petent formations are limestones, dolomites, and consolidated sandstones that
will stand unsupported in a borehole. The most commonly encountered incom-
petent formations are unconsolidated sands and gravels. They will cave read-
ily into the borehole if not artificially supported. There are, of course,
intermediate cases of formations that are generally competent but require
some support for such purposes as preventing sloughing of occasional incom-
petent intervals or preventing fractured blocks from falling into the bore-
hole.
The American Petroleum Institute (1955) described nine completion prac-
tices considered common in the petroleum industry, five methods applicable to
caving formations and four applicable to competent formations. Examination
of the records of wastewater injection wells that have been constructed in the
United States (see the bibliography for Chapter 1) shows that almost all of
the wells constructed thus far have been completed by one of three methods or
close variations of them. The methods are:
1. Open hole completion in competent formations.
2. Screened,or screened and gravel-packed in incompetent
sands and gravels.
3. Fully cased and cemented with the casing perforated
in either competent or somewhat incompetent formations.
f'inures 7-la, b, and c are examples, respectively, of well1-, completed
by the open hole, screen and gravel pack, and fully cased and perforated
met hods.
-------
OPEN-HOLE DESIGN
PITTA PLF *ATKK
NONPOTABLE A'ATER
LIMESi'JNE
18" HOLE
LOLuMITIG
LIMESTONE
LIMESTONE
BASEMENT RCCK
24" STEEL CONDUCTOR CASING
(
9-5/8" STEEL PROTECTION CASING
HOLE
— COMMON CEMENT
6-5/8" GLASS-REINFORCED PLASTIC
INJECTION TUBING
— D.V. TOOL
KEROSENE-FILLED ANNULUS
UNDERREAMED 13-3/4" HOLE
ACID-PROOF CEMENT
INTERFACE
9-5/8" GLASS-REINFORCED
PLASTIC CASING
WASTE
7-7/8" OPEN HOLE
FIGURE 7-1 a. EXAMPLE OF BOTTOM-HOLE COMPLETION BY OPEN HOLE
METHOD (BARLOW, 1972).
236
-------
SCREENED OPEN-HOLE DESIGN
POTABLE WATER
NONPOTABLE WATER
UNDIXFERENTIATED
SANDS,
CLAYS
AND
SHALES
JHALE.
17-1/2" HOLE
13-3/8" STEEL CASING
COMMON CEMENT
12-1/u" HOLE
9-5/8" STEEL CASING
DIESEL-OIL-FILLED
^NNULUS
5-1/2" STAINLESS STEEL
INJECTION TUBING
_ D.V . TOOL
^CID-PRCOF CEMENT
FROM D.V. TOOL TO
JNDERfiEAMED SECTION
ACKEh
.')" HC'LE
ACKED WITH
: •-(.> KKSH GRAVEL
-------
CASED-HOLE DESIGN
POTABLE WATER
NONPOTABLE WATER
UN-DIFFERENTIATED
SANDS,
CLAYS
AND
SHALES
H'1 HOLE
STKEL CASING
DIESEL-OIL-FILLED
ANNULUS
3-1/2" CLASS-REINFORCED
PLASTIC TUBING
D.V. TOOL
ACID PROOF CEMENT !
FROM D.V. TOOL TO BOTTOM I
-5/8" GLASS-REINFORCED
LASTIC CASING
PACKER
PERFORM i'lv NS
^000'
FIGURE 7-lc. EXAMPLE OF BOTTOM-HOLE COMPLETION BY FULLY CASED
AND PERFORATED METHODS (BARLOW, 1972).
238
-------
Open-hole completions are advantageous where they can be used, because
all of the formation is open to receive wastewater, and little casing and no
screen is subject to the corrosive action of the injected waste. Most wells
in hard-rock areas such as Illinois, Indiana, Kansas, Michigan, Ohio, and Okla-
homa are completed in this way.
Screened and gravel-packed wells are used principally in areas where
partially consolidated or unconsolidated sands are the injection intervals.
Such areas are the Gulf Coasts of Texas and Louisiana, and California.
In the third method, the injection casing is installed through the full
depth of the well, and selected intervals are then opened up by perforating
the casing and cement with a series of solid projectiles or small shaped ex-
plosive charges. Perforating is accomplished by lowering a perforating gun
to the desired depth in the cased well, then firing it. Guns available from
one service company are up to 15 feet in length and fire one to four shots
per foot. If intervals thicker than 15 feet are to be perforated, multiple
guns are used. Shot holes are generally less than one-half inch in diameter
and the shots will penetrate the casing and several inches of concrete and/or
rock. This method has been applied to wells in both hard and soft rock areas.
It is relatively easy to construct wells in this way, but the performance of
cased and perforated wells has not been as good as that of wells constructed
by the other two methods. Probably the best use of the method is for recom-
pleting wells at a shallower depth when additional injection capacity is need-
ed or when it is necessary to abandon the original deeper injection interval.
Tubing, Casing & Borehole Program
Most wastewater injection wells will be constructed with injection tub-
ing inside the long casing string, and with a packer set between the tubing
and the casing near the bottom of the casing (Figure 7-2). This design is
not entirely free of problems, particularly with the packer, but experience has
proved it generally superior to other designs. Some wells are completed with
an annulus open at the bottom. The annulus is filled with a lighter-than-
water liquid which "floats" on the aqueous waste (Figure 7-la). With wells
completed with tubing, the first step in establishing the borehole and casing
program is determination of the tubing size.
Tubing size is based on the volume to be injected, but there is no
fixed relation between the two. For a specified waste volume, an increased
tubing size requires less energy to force the wastewater through the tubing,
but increases tubing cost. The optimum tubing size would minimize the
cost of operation and still meet the enqineerinq requirements of the system.
After determination of the tubing size, the inside diameter of the long
or injection string is selected based on the following considerations:
1. Tubinq diam"t.f?r. The inside diameter of the casinq
(liust be (]TTYI( enough t.o dccoinniodc) te trie j Mrk.fr riii'.l
tubinq (coupling dui;nc.kt ,cr) .
-------
PRESSURE GAGE
WELLHEAD PRESSURE
FRESH WATER BEARING —
SURFACE SANDS AND 0 " o ' °
GRAVELS . 0 ; • o
, - ' ' o
o • . ' ° . o
IMPERMEABLE SHALE ^ — - '•
CONFINED FRESH-WATER
BEARING SANDSTONE ; .
IMPERMEABLE ~ -
bHALh \~ — *- , - — . — , —
y
/
/
/
/
/
/
/
/
y'
/
/
/
/
/
/
/
/
/
/
/
^
1
\
\
\
\
^
r>
*
\
s
\
\
\
\
\,
.\
\
\
^
-~^f
4
r^
(
^
V
\
\
\
\
\
\
\
\
iS
\
\
\
\
\
N
\
|\,
s
X
\
\
\
\
\
/
(
'/>
/
/
/
/
/
/
/
/
,/
/
/
/
/
/
y
/
/
/
/
d
t j PRESSURE GAGE
'7~~^7~~T~
o " - , ° • o
0 - 0 • 3
o ' " -
0 , ,.
o ' J
0 -' V
_ — » ^.^ .-
-r SURFACE CASING SEATED
-S BELOW FRESH WAI fcK AN
XL1 CEMENTED TO SURFACE
PERMEABLE SALT-WATER-
BEARING SANDSTONE
INJECTION HORIZON
INNER CASING SEATED IN OR
ABOVE INJECTION HORIZON
AND CEMENTED TO SURFACE
INJECTION TUBING
ANNULUS FILLED WITH
NONCORROSIVE FLUID
PACKERS TO PREVENT FLUID
CIRCULATION IN ANNULUS
OPEN-HOLE COMPLETION IN
COMPETENT STRATA
IMPERMEABLE SHALE
"IGURE 7-2. SCHEMATIC DIAGRAM OF AN INDUSTRIAL WASTE
INJECTION WELL COMPLETED IN COMPETENT
SANDSTONE (MODIFIED AFTER WARNER, 1965).
240
-------
2. Cost of drilling and casing. Since the cost of
drilling and casing increases with hole diameter,
the size should be minimized.
3. Workovers. Since remedial work is frequently
necessary in wastewater injection wells, the casing
size must accommodate workover equipment. During
their lifetimes, many injection wells require some
form of maintenance (''workover" in the terminology
of the petroleum industry). Workovers are commonly
attempted for the following purposes:
a. Well repair
1) Replace damaged tubing and/or packers
2) Repair damaged or corroded casing
3) Perform remedial well cementing
4) Install additional liners or casing
b. Maintenance of injection capacity
1) Reperforating
2) Acidizing
3} Fracturing
4) Mechanical or hydraulic cleaning of the
wel1 bore
c. Recompleting or deepening to a new injection
interval
4. Common practice. The experience of others in the
geologic area of interest and in similar operating
situations should guide the final choice.
Once the inside diameter of the injection string has been selected, then its
other characteristics are determined as discussed in the casing design sec-
tion of this chapter. The decision on the size of the injection casing fixes
the minimum size of the hole and of all other casing strings, '.he hole dia-
meter should be at least two inches gr'Hter than The casing coupling outside
diameter to allow at least a one-inch sneat.h oF •,. ^"ent around the casino
(Amsriran Pptroleuir Insti tutp, 195-V.
-------
Samples
Samples of the rocks penetrated during drilling are always obtained
either in the form of cuttings or as cores, as discussed in Chapter 4 except
in unconsolidated formations, where they may not be obtainable. Cuttings are
routinely obtained, but the number of sets and the collection frequency must
be specified. The collection interval is normally 5, 10, or 20 feet, with
10 feet probably the most common. At least two sets of cuttings are usually
obtained, one set for the well operator and a second set for the appropriate
state agency.
Cores are expensive and time consuming to take and, normally are selec-
tively taken only from the potential injection and confining intervals. In
planning a well, the probable depth and footage of cores should be projected
and arrangements made for the packaging and shipment of the cores to a core-
analysis laboratory.
As with cores, samples of water are selectively taken and the approxi-
mate depth and number of water samples should be projected and the procedures
for sample preservation, shipping, and analysis defined. Samples will usually
be taken by drill-stem testing and it is advisable to contact the service com-
pany that will be performing the testing to establish that equipment and per-
sonnel will be available when needed.
Geophysical Logging Program
The variety of available borehole geophysical logs is outlined in
Chapter 3. In planning the well, the particular logs for determination of
lithology and rock and formation fluid properties are selected. When choos-
ing the suite of logs to be run, it is advisable to consult the logging
companies that operate in the area to determine which logs have been found to
be most suitable to the local geologic conditions and to insure that the sel-
ected service will be available when needed.
Well Tests
At some stage in well construction, possible injection intervals will
be tested. Initial testing will normally be drill-stem testing, during which
reservoir properties are determined in a preliminary way and water samples
are obtained. Later in well development, the most promising injection inter-
val or intervals are tested more thoroughly by injectivity and/or pumping
tests. Each of these types of tests and its interpretation is discussed in
Chapter 3. In planning the well, thought should be given to the types of
equipment needed to perform the injectivity and/or pumping tests and sources
for the equipment identified. Arrangements for on-site facilities and mat-
erials needed for such tests also must be planned. For example, where will
water be obtained for injectivity testing, how will the water be pretreated,
and where will it be stored prior to injection?
242
-------
TUBING AND CASING DESIGN
Tubing
It is recommended that wastewater injection be through tubing, which
can be replaced, rather than through casing which cannot. Also, injection
through tubing provides another level of protection to resources outside of
the borehole and provides an additional opportunity for monitoring in the
tubing-casing annulus.
Selection of injection tubing size is the first step in the actual well
design. As previously mentioned, tubing size is based on the volume of waste-
water to be injected. This is because the injection rate and tubing size
determine the velocity of flow and, thus, the amount of pressure dissipated
during flow through the tubing. Figure 7-3 gives the friction pressure loss
per 100 feet of tubing for various sizes of tubing and casing and for water
with a viscosity of one centipoise. Calculations for the chart also assume
an "average" friction factor for the tubing and laminar flow. Friction pres-
sure losses for circumstances significantly different than the assumed ones
would have to be calculated from friction loss equations given in texts on
fluid mechanics or petroleum engineering.
As a design example, the tubing and casing will be selected for the
Midwest Fuel Recovery Plant site which is discussed in detail in Chapter 5.
As discussed by Trevorrow et. al. (1977), the volume of tritium-bearing low-
level radioactive aqueous waste that would be produced at such a plant would
probably be about 35 gallons/minute, which is about 0.83 barrels/minute.
Rounding this off to one barrel/minute, the friction loss for 1 1/4"
tubing would be about 11 psi/100 feet and the total loss over the approximate
2000 of required tubing would be about 220 psi. This would be tolerable, but
it would also probably increase surface injection pressures from 50 to 100
percent, thus requiring a larger and more expensive pump and motor. By going
to 2 3/8 inch tubing, the total friction loss can be reduced to less than 40
psi and by going to 2 7/8 inch tubing, friction losses would be less than
20 psi. Either size would be suitable, and both are commonly used.
Tubing grade and weight are selected in the same manner as casing grade
and weight, as is discussed in the next section.
Materials used for tubing range from ordinary steel, through plastic,
to the more costly metals such as the various stainless steels; the nature of
the waste is the determining factor. Commonly, sprayed-on plastic linings
are adequate, provided a satisfactory seal can be made at the tubing couplings.
Plastic tubing, particularly of the glass-reinforced type, is being used con-
siderably. This tubing is ideal for some uses.in wells which are not too deep.
The nain difficulty with plastic tubing is its low resistance to collapse and
b u r s t. i n <}.
Bimetallic tubinq has been used successfully in some wells. This type
uf tubinq has a thin-qaqe liner of resistant metal swedqed to the base-metal
wall. The liner is folded over the end of the pipe and welded in position.
-------
1,000
900
800
700
600
500
400
300
ZOO
FRICTION PRESSURE vs FLOW RATE
FOR VARIOUS PIPE DIAMETERS
FLUID VISCOSITY - I cp
TUBING
A - I 1/4 - 1.380"
B - I 1/2" - 1.610"
C -2 3/8 - 1.995"
D -2 7/8-2.441
E-3 1/2"-2.992
DRILL PIPE
F -3 1/2" - 13.3* -2.764"l.D.
CASING
G - 4 1/2 - I I. 6* - 4.000" I.D.
H -5 1/2" -17.0* -4.892" I.D.
I -7" -23.0* -6.366" I.D.
4 5 6 7 8 10 ZO
FLOW RATE — BPM
30 40 60 80 100
FIGURE 7-3. FRICTION PRESSURE LOSS VS. INJECTION RATE FOR COMMON TUBING
AND CASING SIZES. (HALLIBURTON, 1963).
244
-------
As with plastic-lined steel pipe, couplings utilizing a liquid-tight gasket
seal mush be used to prevent access of the waste to the unprotected steel
of the coupling threads (Barlow, 1972).
Casing
In constructing an injection well, the wall of the hole is lined with
a heavy steel pipe, called casing. The primary functions of casing are to
prevent the hole from caving in, confine injection to the wellbore and pre-
vent contamination of upper fresh water bearing zones, and to provide a method
of pressure control. Casing lengths of uniform outside diameter are called
casing strings. Three types of strings may be used (but are not always nec-
essary) in injection wells: a surface string, one or more intermediate
strings (as dictated by geologic conditions), and an injection string.
Six properties determine casing type: wall thickness, outside diameter,
nominal weight, length, joint specification, and construction material. A
section of a casing string is a length of casing having the same wall thick-
ness and joints, and being constructed of the same construction material (i.e.
the same grade of steel); a string of varying sections is a combination string.
When selecting casing, it is necessary to design for three main forces:
internal pressure, external pressure, and axial loading. Internal pressure
would cause the casing to burst whereas external pressure would collapse the
casing. Axial loading may be compressive due to buoyancy or tensive due to
the hanging weight. In the case of axial tension, the hanging weight may
cause the casing to "pull out" at a joint, or collapse due to decreased ex-
ternal pressure resistance.
The grade of steel casing is based on minimum yield strength as stan-
dardized by the American Petroleum Institute (API). Yield strength is the
tensile stress which produces a total elongation of 0.5r; of the length.
Yield strengths of the API casing are given in Table 7-1.
TABLE 7-1. API CASING GRADES AND YIELD STRENGTHS,
(AMERICAN PETROLEUM INSTITUTE, 1975).
YIELD STRENGTH '
GRADE (PS I)
11-40
-------
Other API standards have been established for the remaining casing
properties (American Petroleum Institute, 1975). Normally, in designing cas-
ing strings, it is unwise to subject the casing to its maximum allowable stress
and for this reason, design factors are used. The four main design factors
are for yield strength, joint strength, collapse and burst. A study of design
factors is reported by the American Petroleum Institute (1955-a).
The first step in casing design is selection of the diameter of the long
or injection string, based on the tubing size previously chosen and on the
criteria listed in the discussion of the tubing, casing, and borehole program.
In this example, 7-inch OD casing is suggested. Although a smaller size could
be used, it would limit the choice of packers and make remedial workovers more
difficult. A decision on the size of the injection casing fixes the minimum
size of the hole and all larger casing (Tables 7-3 and 7.4 ). The grade and
weight of the casing will now be determined.
Design for internal pressure is the first step. As a general criterion,
injection wells should be designed for the maximum possible internal stress
that might be developed. This would be reservoir fracturing pressure. For
this calculation, the fracturing pressure gradient will be assumed to be
1.5 psi/ft, with a balancing external reservoir pressure gradient of 0.5
psi/ft, leaving a net internal stress of 1.0 psi/ft. The total net internal
stress in our 2,000 ft. injection casing would then be:
PJ = 2,000 ft x 1.0 psi/ft = 2,000 psi
If a design factor of 1.5 is applied, to allow for possible pressure
surges and to avoid stressing the casing to near its yield point, maximum
internal bursting pressure to design would be:
P-jd = 2,000 x 1.5 = 3,000 psi
If J-55 and N-80 grades of casing are used, the following data apply:
TABLE 7-2. CHARACTERISTICS OF J AND N GRADES OF CASING
(AMERICAN PETROLEUM INSTITUTE, 1975).
Grade
Min. Yield
Strength
Nominal
Weight
Ib/ft
Collapse
Resistance
Internal
Yield
55,000
55,000
55,000
80,000
80,000
80,000
80,000
80,000
80,000
20
23
26
23
26
29
32
35
38
2270
3270
4320
3830
5410
7020
8600
10,180
11,390
3740
4360
4980
6340
7240
8160
9060
9960
10,800
246
-------
TABLE 7-3. RELATIONSHIP BETWEEN CASING SIZE, MINIMUM HOLE SIZE,
AND MINIMUM RECOMMENDED BIT SIZE (BLUM, 1959).
Casing
OD "
4 1/2
5
5 1/2
6
6 5/8
7
7 5/8
8 5/8
9 5/8
10 3/4
11 3/4
13 3/8
16
20
3 3/4
3 7/8
4 1/4
4 5/8
4~i / ,1
j/ '4
Couol inq
OD
5.000
5.563
6.050
6.625
7.390
7.656
8.500
9.625
10.625
11 .750
12.750
14.375
17.000
21.000
TABLE 7-4.
6
6 1/8
6 1/4
6 3/4
7 3/8
Recommendec
Clearance
1.000
1.250
1.250
1.750
1 .750
2.000
2.500
3.000
3.250
3.250
3.500
3.500
3.500
3.500
COMMON BIT SIZES
7 3/4
7 7/8
a 1/2
8 5/H
M 3/4
i Minimum
Hole Siz
6.000
6.813
7.300
8.375
9.140
9.656
11.000
12.625
13.875
15.000
16.250
17.875
20.500
24.500
(BLUM, 1959).
9 5/8
9 7/8
10 5/8
11
i /
Minimum
e Bit Size
6
7
7 3/8
8 3/8
9 1/2
9 3/4
11
13 3/4
14 3/4
15
17
18
20 3/4
25 1/2
12 3/4
15
17 1/7
17 I/?
?3
-------
By checking the internal yield column of Table 7-2, it can be seen
that all of the casing listed will meet the internal yield pressure require-
ments.
Next, the external collapse pressure is determined from:
Pcd = 0.052 Nc x Pc x L
where :
PCCJ = external collapse design pressure
Nc = design factor for collapse
PC = expected external collapse pressure gradient
L = casing length
for this example:
Pcd = 0.052 x 1.125 x 12 x 2000
= 1404 psi
Pc was chosen on the basis of the expected drilling mud weight of 12 Ib/ft3.
The design factor was obtained from Craft, et. al . (1962). Again, from
Table 7-2, all of the casing meets the requirements in the collapse resistance
criteria. Since all weights of casing will satisfy the pressure requirements
thus far, select the lightest weight, J-55, 20 Ib/ft. and calculate the maxi-
mum allowable length of this section. First, determine the maximum allowable
suspended weight based on joint strength:
Wj = Fj/Nj
- 254,000/2.00
= 127,000 Ib.
where:
F,- = joint strength of API J-55,
20 Ib/ft casing, with short
thread and coupling
N, = design factor (Craft, et. al., 1962)
U
Second, determine the maximum allowable suspended weight based on yield
strength:
Wy = m = 55,000 X . = 184.7121bs.
Na i . Ło
248
-------
where:
Y = minimum yield strength of J-55,
20 Ib/ft casing (Table 7-4)
A,- = root thread area (Craft, et. al.,
J 1962)
Na = design factor (Craft, et. al.,
1962)
Therefore, the maximum suspended weight is limited by joint strength and the
maximum length that can be suspended is
127'000 = 6350 ft.
20
which is greater than the setting depth. For this example, the injection
string would consist entirely of J-55, 20 Ib/ft, short thread casing. Although
F-25 or H-40 casing grades are available in 7" outside diameter, only J-55 and
N-80 grades were considered due to common usage.
Finally, the surface string must be designed. Since the surface casing
is set in the hole prior to drilling for the injection string, the surface
casing size will be determined so as to accommodate the drill bit for the in-
jection string. Having selected a 7" outside diameter casing for the injec-
tion string, the minimum hole size for the injection string is found to be
9 7/8" from Table 7-3. API specifications indicate the minimum surface cas-
ing size that will allow the 9 7/8" drill bit is 10 3/4". Since this string
will be only 100' long, to support the Maquoketa shale section, and is not
dependent on the injection string weight, J-55 grade will be considered due
primarily to availability (N-80 is eliminated due to the short length require-
ment) .
Determining the necessary data as in the injection string, but for
10 3/4" OD casing:
TABLE 7-5. PROPERTIES OF J-55, 10 3/4 IN. CASING
(AMERICAN PETROLEUM INSTITUTE, 1975 AND
CRAFT ET. AL., 1962).
Grade
Win.
Str
- P.5
55,
F,b ,
Yield
enqth
~i
000
000
,'ljVi
Nominal
Wei qht
Ib/ft.
40 . :.;,
4 r; . i-,
' , l :'
Col lapse
Re si stance
P s i
i,;::;0
?300
9 0 7 ;•
Internal
Yield
P.si
31 30
3580
," '';'-"",
(Continued
-------
TABLE 7-5. CONTINUED
Root
Thread Area
in?
9.045
10.616
12.171
Minimum Joint
Short Thread
Ib.
450,000
518,000
585,000
Strengths
Long Thread
Ib.
NA
NA
NA
Following the same general design procedures as for the injection
string, J-55, 40.5 Ib/ft casing with short threads and coupling is selected.
The final casing design for the Midwest Fuel Recovery Plant is:
Injection Well Casing Design
Type Grade Weight Interval Coupling
Ib/ft. ft.
Surface J-55 40.5 0-100 short
Injection J-55 20 0-2500 short
A thorough casing design analysis including necessary casing data is
presented by Craft, et. al. (1962).
Because injection tubing and a packer are to be used, the majority of
the casing can be of ordinary steel, but the last joints should be of a corro-
sion resistant metal. According to Long (1967), past experience in the nu-
clear industry has shown that stainless steels of types 309 SCb, 347, and 304
L are suitable in reprocessing operations and these metals would, thus, be
ones to consider. Corrosion is discussed in detail in Chapter 5.
PACKER SELECTION
Packers are designed to seal off, or "pack off" certain sections in
an injection well. They may be used to separate multiple injection zones,
for casing protection from formation pressure and fluids, to isolate given in-
jection zones, and as a subsurface safety control. There are three main types
of packers: mechanical-set, hydraulic-set, and permanent packers. In order
to set a packer and effectively seal off a reservoir zone, metal wedges, call-
ed slips, are forced against the casing wall to hold the packer in position
and then the packing element is expanded to form a seal with the casing.
Mechanical set packers are seated by movement of the tubing. This may
be accomplished by use of the tubing weight as in the case of a compression
or weight-set packer; this packer may be retrieved by simply lifting up on
the tubing.
250
-------
Tension-set packers (as shown in Figure 7-4) are set by a pulling ten-
sion on the tubing; they are released by slacking off on the tubing. As can
readily be seen, tension-set packers will be set even tighter by pressure
from below and therefore work well in injection wells.
Rotational-set packers are set using a left-hand rotation to extend the
slips; this procedure is reversed to release the packer. The primary ad-
vantage of rotational packers in injection wells is that the tubing may be
landed in a neutral-weight situation, thus eliminating the possibility of un-
seating the packer due to tubing elongation (as when using a tension-set
packer) or separating due to contraction (as when setting a weight-set packer.)
The main disadvantage of rotational-set packers is that solids tend to settle
out on top of the packer which prevents any rotational action; thus, on at-
tempting to release the packer, the tubing is unscrewed. A brine water flush
prior to retrieval will facilitate packer release.
The second major type of packer is the hydraulic-set packer which em-
ploys fluid pressure to wedge the slips; once set, this type of packer is
usually held by a mechanical lock. Retrieval is by either rotation or tension.
Hydraulic set packers are used particularly where tubing movement is limited.
This type of packer also allows the tubing to be in a neutral-weight state.
A special type of the hydraulic-set packer is the inflatable or "bal-
loon" packers which are used in open hole or cased wells. The packer element
is set by applying fluid pressure. Primary usage occurs in wells with par-
tially collapsed casing. Inflatables will not withstand high pressure dif-
ferential s.
Permanent packers are set by either wireline, tubing, or even drill
pipe. Normally, they are nonretrievable, but will withstand high pressure
differentials. When set by wireline, a powder charge is ignited and the gas
pressure sets the packer; when set with tubing or drill pipe, either hydraulic,
tension, rotation or a combination of these methods may be used.
Another type of permanent packer is a cement plug; however, this tech-
nique is obviously very permanent. Packer expense is eliminated and leaks
may be sealed by spotting cement. This technique consists of cementing the
tubing in place and thus limits future workover possibilities.
DRILLING THE WELL
Oil and gas wel1s are drilled primarily with rotary drills and this
type of equipment is, therefore, the most readily available and widely used
for drilling injection wells. Rotary drilling involves boring a hole by us-
ing a rotating bit, to which a downward force is applied. The bit is attached
to and rotated by steel drill pipe and collars through which a drilling fluid
is circulated. Generally, the fluid leaves the drill string at the bit,
thereby cooling and lubricating the cutting face of the bit. By flowing
across the cutting surface, the drilling fluid drags rock cuttings from the
hole bottom and transports them to the surface through the annul us between
the drill string and the borehole wall. Figure 7-b shows the components of
r! rot a ry iir i 1 ! s t. r i MCJ .
-------
en
73
3= t—t
s i
m ,
" C/O
-------
lli/ mini
llJ JV/ll ii
Mud
To pits
FIGURE 7-5.
Tool joint
Drill pipe
Drill collars
SCHEMATIC DIAGRAM OF THE
COMPONENTS OF A ROTARY DRILL
STRING. BIT LOAD IS
FURNISHED BY HEAVY-WALLED,
LARGE-DIAMETER DRILL COLLARS
(GATLIN, I960).
-------
Drilling Fluids
The fluid circulated in the borehole is extremely important in the ro-
tary drilling operation. The drilling fluid may be plain water, water mixed
with various additives, air or gas, or an oil-base fluid. The most common
drilling fluid is water mixed with clays and other additives, which has led
to the commonly used term "drilling mud." According to Gatlin (1960) and
Moore (1974) the primary functions of the drilling fluid are:
Lifting cuttings from the bottom of the hole to the
surface and to suspend cuttings at times when drill it
ic ctnnnorl
2. To cool and lubricate the drill bit and drill string.
3. To control subsurface pressures.
4. To wall the hole with an impermeable mud cake.
5. To provide an aid to formation evaluation and to protect
formation permeability.
Gatlin (1960) and Moore (1974) expand on these functions and discuss
the properties and technology of drilling fluids. Planning of the drilling
fluid program and control of the drilling fluids during drilling is extremely
important to the success of an injection well. Moore (1974) states that
"Many believe that any problems in drilling can be related to the drilling mud,
As a general answer, mud cannot be blamed with all the problems; however, mud
has been properly termed the heart of the drilling operation." Davis and
Funk (1972) stress the importance of drilling fluid selection in order to min-
imize loss of permeability in the injection zone. Figure 7-6 shows the drill-
ing mud circulation and treating system of a rotary drill rig.
Drilling Hazards
Major hazards encountered during drilling are often spoken of as hole
problems. Common hazards or hole problems include deviation from the verti-
cal, lost circulation, hole enlargement and sloughing, and pipe sticking.
Deviation --
No wells are truly vertical, but wells that deviate only slightly are
considered vertical, for practical purposes. Severe hole deviation is un-
desirable because it creates difficulties in drilling, well completion, and
well maintenance. While hole deviation cannot be entirely eliminated, it can
be controlled. Gatlin (1960) and Moore (1974) discuss hole deviation and its
control in detail.
Lost Circulation --
Lost circulation is defined as the loss of substantial quantities of
whole mud to a formation while drilling. This is evidenced by the complete
254
-------
DRILL PIPE
:' •-X^.^. :-,v:--:v V "*\-vN^ /^.::
M ^ -• ^^'\^m^
S.yXL'LLS
MIL I. COLLAR
/'•(>. HOTARY RIC, l)K]l.ll'it] MUD A'JU C I RC.l',1 A f ION AND
-------
or partial loss of return flow of mud. The annular mud level may drop out of
sight and stabilize at a pressure in equilibrium with formation pressure.
Lost circulation occurs when formation permeability is sufficiently great to
accept whole mud. That is, the interconnected voids are too large to be
plugged by the solids in the mud. A further obvious requirement is that the
mud column pressure must exceed the formation pressure. Some of the undesir-
able effects of lost circulation are the following:
1. Mud costs prohibit continuance of drilling without returns.
2. No information on the formation being drilled is available
since no cuttings are obtained.
3. The possibility of sticking the drill pipe with a resulting
fishing job is increased.
4. Loss of drilling time and consequent cost increase is in-
curred.
5. If the lost circulation zone is a potential injection zone,
considerable injectivity impairment may result.
The types of formations to which circulation may be lost have been
classified in three groups:
1. Coarsely permeable rocks, such as gravels
2. Faulted, jointed, and fissured formations such as:
a. those with naturally occurring fractures
b. those in which the fractures are induced
or caused by mud column pressures
3. Cavernous and open fissured formations.
Table 7-6 lists some identifying features of the types of lost-circu-
lation zones.
Lost circulation is commonly combatted by introduction of "lost circu-
lation" materials to plug or bridge the formation openings. Some types of
lost circulation materials are:
1. Fibrous materials: hay, sawdust, bark, cottonseed hulls,
cotton bolls, cork.
2. Lamellated (flat, platy) materials: mica, cellophane.
3. Granular bridging materials: nut shells, perlite, pozzo-
lanic materials, ground plastic.
Fibrous and lamellated materials are most effective in coarsely per-
meable rocks where the voids are relatively small. Larger openings require
256
-------
TABLE 7-6. IDENTIFYING FEATURES OF LOST CIRCULATION
ZONES (HOWARD AND SCOTT, 1951).
Unconsolida ted
For~a t ions
Gradual lowering
cf ---jd level in
_Natiira]_F>^tures Induced Fractures
Loss :;iay become
complete if dril-
ling :5 continued.
Since it is known
trial the rock per-
meabi1i ty must ex-
ceed about 10 darcys
before 'nud can pen-
etrato and that oil
or qas sand permea-
bility seldom exceeds
about 3.5 darcys, it
is i-prohable that
loose sands are the
cause of mud loss to
an oi i or gas sand,
unless the loss can
be attributed to the
ease wi th which thi s
tvne of fornation
Cavernous Zones
1. May occur in any
type rock.
2 . Loss i s evidenced
by gradual lowering
of mud in pits. If
drilling is continued
and more fractures
are exposed, complete
loss of returns may
be experienced.
4.
May occur in any
type rock, but
would be expected
in formations with
character!stically
weak planes.
1 . Normally confined
to limestone.
2.
5.
Loss is usually sud- 3.
den and accompanied
by complete loss of
returns. Conditions
are conducive to the
forming of induced 4.
fractures when mud
weight exceeds 10.5
Ib/gal.
Loss may follow any
sudden surges in
pressure.
When loss of circu-
lation occurs and
adjacent wel1s have
not experienced lost
circulation, induced
fractures should be
suspected.
Can be competent or
incompetent formations.
Loss of returns
may be sudden and
complete.
Bit may drop from
a few inches to
several feet just
preceding loss.
Drilling may be
"rough" before
loss.
-------
TABLE 7-7. SUMMARY OF WELL CEMENTING
ADDITIVES (SMITH, 1976)
Type of Additive
Use
Chemical Composition
Benefit
Type of Cement
Accelerators
Retarders
en
O3
Weight-reducing
additives
Heavy-weight
additives
Additives for
control 1 ing
lost circula-
tion
Reducing WOC time
Setting surface pipe
Setting cement plugs
Combatting lost
circulation
Increasing thick-
ening time for
placement
Reducing slurry
viscosity
Reducing weight
Combatting lost
circulation
Combatting high
pressure
Increasing slurry
weight
Bridging
Increasing fillup
Combatting lost cir-
culation
Calcium chloride
Sodium chloride
Gypsum
Sodium si 1icate
Dispersants
Sea water
Lignosulfonates
Organic acids
CMHEC
Modified ligno-
sulfonates
Bentonite-atta-
pulgite
Gilsonite
Diatomaceous earth
Perlite
Pozzolans
Hematite
Ilmenite
Barite
Sand
Dispersants
Gilsonite
Walnut hulls
Cellophane flakes
Gypsum cement
Bentonite-diesel
oil
Nylon fibers
Accelerated setting
High early strength
Increased pumping
time
Better flow prop-
erties
Lighter weight
Economy
Better fillup
Lower density
Higher density
Bridged fractures
Lighter fluid columns
Squeezed fractured
zones
Minimized lost circu-
lation
All API Classes
Pozzolans
Diacel systems
API Classes D, E,
G, and H
Pozzolans
Diacel systems
All API Classes
Pozzolans
Diacel systems
API Classes D, E,
G, and H
All API Classes
Pozzolans
Diacel systems
(Continued)
-------
Conti nued
Use
Chemical Composition
Benefit
Type of Cement
^d-
i me
Squeeze cementing
Setting long liners
Cementing in water-
sensitive formations
Reducing hydraulic
horsepower
Densifying cement
slurries for plug-
ging
Improving flow prop-
erties
Primary cementing
High-temperature
cementi ng
Neutrali zing mud-
treating chemicals
Tracing flow patterns
Locating leaks
High-temperature ce-
ment i ng
High-temperature ce-
menting
Polymers
Dispersants
CMHEC
Latex
Organic acids
Polymers
Sodium chloride
Lignosulfonates
Sodium chloride
Silicon dioxide
Paraformaldehyde
Sc 46
Silica-1ime re-
actions
Silica-1ime re-
actions
Reduced dehydration
Lower volume of
cement
Better fill-up
Thinner slurries
Decreased fluid loss
Better mud removal
Better placement
Better bonding to
salt, shales, sands
Stabilized strength
Lower permeability
Better bonding
Greater strength
Lighter weight
Economy
Lighter weight
All API Classes
Pozzolans
Diacel systems
All API Classes
Pozzolans
Diacel systems
All API Classes
All API Classes
API Classes A, B,
C, G, and H
All API Classes
(Continued)
-------
en
o
TABLE 7-7. Continued
Type of Additive Use Chemical Composition Benefit Type of Cement
Gypsum cement Dealing with special Calcium sulfate Higher strength
conditions Hemihydrate Faster setting
Hydromite Dealing with special Gypsum with resin Higher strength
conditions Faster setting
Latex cement Dealing with special Liquid or powdered Better bonding API Classes A, B,
conditions latex Controlled filtra- G, and H
tion
-------
TABLL
DIGEST OF CONDITIONS AND RECOMMENDED PRACTICE IN PRIMARY CEMENTING (SMITH, 19761
••I'VMvs S'jc, in.
-.<•-tti n<:: deoth, ft.
nt i.iuniped to
T-U API Class
ti VPS norna 1 1 y
d wi V" r onion t
Conductor P_ij)e_
7 to 20
40 to 4,500
Probably enlarged
Native
Viscous,
Surface
thick cake
20 to 30
30 to 1,500
Probably enlarged
Na ti ve
Viscous, thick cake
Surface
A, G, H
2 to 3 percent CaCl
Like initial slurry,
densified (ready-
mix concrete may be
dumped into annul us)
Through drillpipe using
small plugs and seal-
ing sleeve, or down
casing wi th 1arge
plugs, or into annu-
1 us; f1 oat collar may
or may not be used.
Generally less than 30 Generally less than 45 min.
in in.
A, G, H
Bentonite or pozzolan
Densified for high strength
(deep well may use high-
strength slurry for entire
job)
Same as for conductor pipe
Centralize lower casing
Intermediate and/or
Production String
4 1/2 to 11 3/4
1 ,000 to 15,000
Probably enlarged (particu-
larly in salt)
Native or water-base
Controlled viscosity and con-
trolled fluid loss
Surface pipe or lower, de-
pending on conditions
A, C, G, H
High gel, filter, or pozzolan
bentonite; dispersant + re-
tarder if needed; salt, for
cementing through salt sec-
tions
Densified for high strength
over lower 500 to 1,000 ft
Down casing with plugs (top
and bottom), or in stages,
depending on fracture gra-
dient. If string is very
heavy, it may be set on bot-
tom and cemented through
ports. Use float collar and
guide shoe; centralize in
critical areas.
Variable, depending on cement
volume--45 min.to 2 1/2 hrs
'ContinuedT
-------
TABLE 7-8. Continued
Conductor Pipe
Surface Pipe
Intermediate and/or
Production String
Placement rate
WOC time
Mud/Cement spacers
Cementing hazards
Low or high
6 to 8 hours, depend-
ing on regulations
Plugs and water flush
Casing can be pumped
out of hole; cement
may fall back down
the hole after it
has been circulated
to surface.
High
6 to 12 hours, depending
on regulations
Plugs and water or thin
cement
Same as for conductor.
Lower joints may be lost
down the hole with deeper
drilling; casing can
easily stick.
01
ro
High
6 to 12 hours, depending on
regulations
Plugs and thin cement, or
spacer compatible with mud
There may be both weak and
high-pressure zones, re-
quiring variable-weight
cement slurries. Prolonged
drilling may damage casing.
Wells may be hot, necessi-
tating measurement of bot-
tom-hole temperatures.
-------
use of a granular material having sufficient strength to form a bridge across
the void. These effects are well illustrated by the work of Howard and Scott
(1951). In their experiments, mud containing various concentrations and types
of lost circulation materials was circulated through different sizes of slots
or simulated fractures. The slots were considered sealed when the plugging
materials withstood 1000 psi differential across the fracture. The main con-
clusions of this study were:
1. Granular bridging materials are the most effective
lost circulation agent in fractured rocks.
2. Concentrations of 20 Ib/bbl gave maximum results
and little increase in plugging will result from
higher concentrations.
The materials evaluated and the maximum size fractures sealed by each
are shown in Figure 7-7.
Hole Sloughing and Enlargement
Hole sloughing and enlargement are problems generally associated with
shale. Some areas are characterized by shale sections containing bentonite
or other hydratable clays which continually adsorb water, swell, and slough
into the hole. Such beds are referred to as heaving shales and constitute
a severe drilling hazard when encountered. Pipe sticking, excessive solid
buildup in the mud, and hole bridging are typical resultant problems. Various
treatments are sometimes successful, such as (Gatlin, 1960):
1. Changing mud system to inhibitive (high calcium content)
type such as lime or gypsum which reduces tendency of
the mud to hydrate water-sensitive clays.
2. Increasing circulation rate for more rapid removal of
particles.
3. Increasing mud density for greater wall support.
4. Decreasing water loss of mud.
5. Changing to oi1-emulsion mud.
6. Changing to oil-base mud.
Moore (1974) cites the addition of Chrome Lionosulfonate to drilling muds and
the use of potassium chloride-polymer muds as relatively recent developments
in the control of sloughinq shales.
Hole cnlargenen! can a 1 so be a problcr; in are as where soluble PVfiporit.es.
as salt, are present in the geologic section. Hole enl argei'ient increases
required volumes of drill inn cujcl and casing oenent and may make it diffi-
!.o obtain a good cementing .job. The principal [".pan1, of "' '"' * sa 1 t •• sa t.;;ra * eel '"u : .
-------
MATERIAL
TYPE
DESCRIPTION
CONCEN-
TRATION
Lb/bbl
LARGEST FRACTURE SEALED
Inches
0 .04 .08 .12 .16 .20
ro
CTi
Nut shell
Plastic
Limestone
Sulphur
Nut shell
Expanded Perlite
Cellophane
Sawdust
Prairie hay
Bark
Cotton seed hulls
Prairie hay
Cellophane
Shredded wood
Sawdust
Granular
Lamellated
Fibrous
Granular
Fibrous
Lamellated
Fibrous
50%-3/16+10 Mesh
50%-10+100 Mesh
50%-10+16 Mesh
50%-30-1-100 Mesh
50%-3/16+10 Mesh
50%-10+100 Mesh
3/4 inch Flakes
1/4 inch Particles
1/2 inch Fibers
3/8 inch Fibers
Fine
Ve inch Particles
1/2 inch Flakes
1/4 inch Fibers
Vie inch Particles
20
20
40
120
20
60
8
10
10
10
10
12
8
8
20
FIGURE 7-7. SUMMARY OF RESULTS OF TESTS OF LOST CIRCU-
LATION MATERIALS (HOWARD AND SCOTT, 1951).
-------
Pipe Sticking --
The drill string may become stuck in the hole during drilling for a
variety of reasons. Gatlin (1960) lists some of the causes of stuck pipe as:
1. Foreign objects or so called "junk" in the hole.
2. Sloughing formations (see above).
3. Cuttings settling above the drill bit or drill
collars.
4. Bit and drill collar balling.
5. Key seating.
6. Pressure-differential sticking.
The first four of these are self-explanatory.
Key seating occurs when drilling below a dog-leg in a hole. The drill
pipe presses against the hole, wearing a groove in it. On coming out of the
hole, the drill collars may jam in this groove or seat and become stuck.
Pressure-differential sticking is caused by the greater pressure in the
mud column literally gluing drill pipe to the borehole wall adjacent to a
permeable formation.
Moore (1974) and Gatlin (1960) discuss methods of preventing pipe stick-
ing and dealing with stuck pipe.
Casing_I_nsta11ati on_
Prior to installation of casing, the borehole must be conditioned to
prepare it for cementing. Conditioning is accomplished by circulating mud to
clean the borehole. If the hole has been sitting open for a long period dur-
ing logging and testing, it is also good practice to make a clean-up run with
the drilling string before running casing.
After conditioning the hole, casing is "run11 into the hole and then
cemented, as discussed in the next section.
CEMFNTING
Primary cementing of deep wells i'. the process of mixing a slurry of
cement and water and pumping it down, usually through casing, into the open
hole below the casing. The lenient is then forced upward, under pressure, ir.'to
the annulus between the casing and the borehole or between the i, as JIT.: and pre-
viously installed larger rasing (figure' 7-H). Although cenent is ns>c::-.allv
r-iiip 1 aced through the casing, sevets.il other" methods are available lor special
s i t ua ! i ni>s , as shown i n F igure /-''.
-------
SURFACE CASING
PRODUCTION CASIN
DISPLACEMENT FLUID
GUIDE SHOE JOS i-. ri-OCESS
CO
o
C_3
>-
Cd
CSL CTi
D- i—
oo
i
oi
CD
-------
Cement
Lost to
Weak
Zone
fr^gZazE*
'/A.
Set Cement
NORMAL
DISPLACEMENT
METHOD
TWO
STAGE
CEMENTING
INNER
STRING
CEMENTING
OUTSIDE
CEMENTING
'•!
•$
if - 4
•
- ji
"•
•'
Weak
Zones
IJffiS -Speoal
Floal
Shoe
O
REVERSE
CIRCULATION
CEMENTING
DELAYED SET
CEMENTING
I
M'uiTiPLF
STRING
CEMENTING
FIGURE: 7-9. ••IITHODS or FMPIACING CTMINT nufUNG
-------
The two principal functions of primary cementing are to restrict fluid
movement between formations and to bond and support the casing. Cement also
aids in protecting the casing from external corrosion and isolates high pres-
sure or lost circulation zones. Another type of cementing procedure, squeeze
cementing, is used to correct defective primary cementing jobs. In squeeze
cementing, cement is selectively placed to fill intervals not completely cem-
ented during primary cementing. Squeeze cementing can also be for other pur-
poses, such as selective plugging of an injection interval without abandonment
of the entire well.
A comprehensive monograph concerning well cementing has recently been
published by the Society of Petroleum Engineers (Smith, 1976). Much of the
material in this section is drawn from that publication.
Cements and Cement Additives
Oilwell cements are classified by the American Petroleum Institute
(1975-a) into eight categories (A to H) according to their suitability for use
at various depths and temperatures and according to other characteristics as
described below:
Class A: Intended for use from surface to a depth of 6,000
feet when special properties are not required.
Available only in Ordinary type (similar to ASTM
C150, Type I).
Class B: Intended for use from surface to a depth of 6,000
feet when conditions require moderate to high sul-
fate resistance. Available in both Moderate (sim-
ilar to ASTM C150, Type II) and High Sulfate Re-
sistant types.
Class C: Intended for use from surface to a depth of 6,000
feet when conditions require high early strength.
Available in Ordinary type and in Moderate and
High Sulfate Resistant types.
Class D: Intended for use at depths from 6,000 to 10,000
feet and at moderately high temperatures and
pressures. Available in both Moderate and High
Sulfate Resistant types.
Class E: Intended for use at depths from 10,000 to 14,000
feet and at high temperatures and pressures.
Available in both Moderate and High Sulfate Re-
sistant type.
Class F: Intended for use at depths from 10,000 to 16,000
feet and at extremely high temperatures and pres-
sures. Available in High Sulfate Resistant type.
263
-------
Class G: Intended for use as a basic cement from surface
to a depth of 8,000 feet as manufactured. With
accelerators and retarders it can be used at a
wide range of depths and temperatures. It is
specified that no addition except calcium sul-
fate or water, or both, shall be interground
or blended with the clinker during the manu-
facture of Class G cement. It is available in
Moderate and High Sulfate Resistant types.
Class H: Intended for use as a basic cement from surface
to a depth of 8,000 feet as manufactured. This
cement can be used with accelerators and retard-
ers at a wide range of depths and temperatures.
It is specified that no additions except calcium
sulfate or water, or both, shall be interground
or blended with the clinker during the manufac-
ture of Class H cement. Available only in Moder-
ate Sulfate Resistant type.
In addition to the cements listed above, there are a number of cementing
materials with special characteristics for which API standards do not exist.
Their uniformity and quality are controlled by the supplier. These materials
include (Smith, 1976):
1. pozzolanic-portland cements
2. pozzolan-1ime cements
3. resin or plastic cements
4. gypsum cements
5. diesel oil cements
6. expanding cements
7. refractory cements
8. latex cement
9. cement for permafrost environments
Several of these special cements have properties that make them of particular
interest in wastewater injection well cementing. Resin and plastic cements
are particularly chemically resistant and are recommended for cementing the
bottom of injection casing, where injected chemical s are in contact with the
c(.'merit (Barlow, lf*7?; Smith, 1976). ixpandinq cements hove been recommended
for- injection wells because of the particularly 1 ighf seal they can forn
atiainst the cacincj and borehole.
-------
According to Smith (1976), more than 40 additives are in use to provide
optimum cement slurry characteristics for any downhole condition. Cement addi-
tives are classified as:
1. Accelerators
2. Light-weight additives
3. Heavy-weight additives
4. Retarders
5. Lost-circulation-control agents
6. Filtration-control agents
7. Friction reducers
8. Specialty materials
Table 7-7 summarizes the most common additives, their uses and benefits,
and the cements to which they can be added.
Primary Cementing
A successful primary cementing job is considered to be as important as
any aspect of injection well construction. A poor cement job can allow mi-
gration of wastewater in voids between injection casing and the borehole. In
some cases freshwater-bearing formations could even be endangered, but perhaps
the greatest danger is from external corrosion of injection casing that can
lead to loss of the well. Smith (1976) discusses primary cementing in de-
tail; the most important points of which are summarized in Table 7-8. The
information in Table 7-8 is directed toward oilfield operations and this must
be considered when applying the recommendations to injection wells.
In injection well operations, the primary cement job should always be
checked. Methods of checking include temperature surveys, cement bond logs,
and radioactive tracer surveys. Temperature surveys and radioactive tracer
surveys are used for locating the top of cement behind casing. Cement bond
logs are used to indicate how successfully the cement has been placed behind
the casing. These logs are discussed further in Chapters 3 and 9.
It should be noted that the drilling and cementing of wells is regula-
ted in many states. Such aspects of casing and cementing are regulated as:
1. The method of setting casing
2. The volume of cement emplaced
3. The time that cement must be allowed to harden
(waiting on cement time - WOC time) before
drilling resumes or the well is completed.
270
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4. The testing of cement jobs.
Many of the applicable laws and regulations are summarized by the American
Petroleum Institute (1975-b).
Casing Equipment
Casing design has been discussed earlier in this chapter. Supplemen-
tary equipment that is used with casing to assist in its emplacement and ce-
menting includes flotation equipment, cementing plugs, stage tools, cementing
baskets, centralizers, and scratchers. Of these items, casing centralizers
and scratchers are of particular interest here because of their importance in
obtaining a good cement job.
Casing centralizers are, as their name implies, used to center a casing
string in the borehole. Types of casing centralizers are shown in Figure 7-10.
Because the success of a primary cement job hinges on the proper centralization
of casing (Smith, 1976), centralizers are essential in injection well construc-
tion. The American Petroleum Institute (1973) has published specifications on
the proper placement of centralizers. Recommendations for the use of centrali-
zers is also available from oilfield supply companies.
Casing scratchers or wall cleaners are devices that attach to the out-
side of casing to remove loose drilling-mud cake from the wellbore so that
the cement can bond to the formation. Scratchers also, like centralizers,
help to distribute the cement uniformly around the casing. Scratchers are
classed as either rotating or reciprocating types, depending on whether they
are used as the casing is either rotated or worked up and down. Examples of
the two types are shown in Figure 7-11. Reciprocating scratchers can be used
in any well, but rotating scratchers are subject to damage in wells where cas-
ing cannot be freely rotated, such as deviated holes.
CASING LANDING
Landing of casing is the transfer of its weight to the well head or cas-
ing hanger after cementing.
An American Petroleum Institute Committee on Casing Landing Practices
(1955-b) reviewed the records of 3700 wells ranging in depth from 2,000 to
14,000 feet. The casing strings in these wells were landed by one of the
four following methods:
1. Landing as cemented
2. Landing in tension at the freeze point (top of cement)
3. Unstressed landing at the freeze point
•"( . Landing in compression at the freo/o point.
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FIGURE 7-10. TYPES OF CASING CENTRALIZERS
(SMITH, 1976).
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FIGURE 7-11.
TYPES OF SCRATCHERS: a.
TING, b. RECIPROCATING
ROTA-
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274
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Based on the committees review, it was recommended that casing be landed as
cemented in all but exceptional cases. That is, the weight of the casing be
supported at the wellhead, just as it was prior to cementing.
WELL STIMULATION
The term stimulation is used in the petroleum industry to include treat-
ment methods applied to a well bore and to the immediately adjacent rock re-
servoir to improve the flow characteristics of the well and the reservoir.
Stimulation methods may be mechanical or chemical or a combination of both.
Terms comparable to stimulation, as used by the water-well industry, are dev-
elopment, redevelopment, rehabilitation, and reconditioning. In this chap-
ter, the discussion of stimulation focuses on well development methods applied
during well construction. Redevelopment, rehabilitation, and reconditioning
techniques are used to improve the performance of operating wells that have
suffered loss of efficiency.
Koenig (1960) performed a systematic review of stimulation methods used
in the petroleum and water-well drilling industries and grouped them into five
major categories. His categories are: surging, shooting, vibratory explosion,
pressure acidizing, and hydraulic fracturing. Koenig's (I960) order of list-
ing supposedly was from the most familiar to the less familiar. The listing
may very well reflect the order of familiarity of the methods to workers in
the water-well industry, but acidizing and hydraulic fracturing are by far
the most widely used stimulation methods in the petroleum industry today.
Gatlin (I960) classifies acidizing, hydraulic fracturing, and nitro-shooting
as large-area penetrating methods. That is, they can increase formation per-
meability for a considerable distance away from the well bore. Gatlin (1960)
classifies perforating, mud-acid washing, jet acidization, and detergent wash-
ing as skin-breaking methods. Skin-breaking techniques are used to remove
drilling mud or other deposits from the formation face or to improve permea-
bility within a few inches of the formation face in the zone where drilling
mud infiltration or other damage may have occurred.
Acidizing
Acidizing involves the injection of acid into an acid-soluble reservoir
rock where its dissolving action enlarges existing voids and thereby increases
the permeability of the reservoir. The acid most commonly used is 15 percent
hydrochloric acid, which reacts with limestone and dolomite. Hydrochloric
acid does not dissolve noncarbonate minerals, such as the silicates in sand-
stone reservoirs, but some sandstones contain sufficient calcite or dolomite
so that acidizing is useful. Numerous additives are used along with the hydro-
chloric acid for particular reasons. Inhibitors are often used to retard cor-
rosion of tubing and casing during acid injection. Hydrofluoric acid is com-
monly combined with hydrochloric acid to form a mud acid. The mud acid is so
named because the hydrofluoric acid reacts with the silicate minerals present
in drilling muds. Mud acid may be used in small volumes to prepare a well
for a larqer convent, in rial acid treatment or it may be the only treatment used.
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Hydraulic Fracturing
Hydraulic fracturing was first introduced to the petroleum industry in
1948 (Clark, 1949). The basic procedure, which is described in detail in
Chapter 3, is the injection of a fracturing fluid into the reservoir zone
under sufficient pressure to open existing fractures and create new ones. Be-
cause the fractures tend to close when the pressure is allowed to return to
normal, propping agents are injected with the fluid to keep the fractures open.
Silica sand of a carefully selected size is a common propping agent. Various
fluids are used for fracturing, including acid, as described above. The
treatment is then referred to as acid-fracturing.
Hydraulic fracturing is a controversial stimulation procedure to some
because it is thought that there may be a danger of opening fractures across
confining beds as well as within the injection interval itself. There would
be little concern about fracturing of confining beds where thousands of feet
of confinement exists and where the fracture treatment is of limited scope.
On the other hand, an extensive fracture program in an injection interval
overlain by thin confining beds would probably be unwise. It is universally
considered that continuous injection of the wastewater at pressures above the
fracturing level is poor practice.
Other Stimulation Methods
The third large-area stimulation method listed above is nitro-shooting.
The use of explosives to shatter the rock adjacent to the borehole is practi-
cally as old as the oil industry. However, stimulation with explosives is
little used today, as it has been almost entirely replaced by hydraulic frac-
turing and perforating, which is described earlier in this chapter.
Mud-acid washing is treatment of the borehole wall with mud acid, as
described above, to reduce formation damage from coating and invasion of drill-
ing mud. A high velocity jet may be used to obtain a more effective result,
in which case the treatment is jet acidization. Jetting is also performed
without acid.
Chemicals other than acid are also used for stimulation. Surface active
agents, for example, have been found useful in removing flow restrictions re-
sulting from emulsions and/or swelling of clays (Gatlin, 1960).
Campbell and Lehr (1973) provide a well-referenced summary of petroleum
and water-well industry stimulation technology.
COMPLETION REPORTS
The preparation of a wel1-completion report is considered to be an es-
sential step in the proper engineering and regulatory processes. Well com-
pletion reports describe in detail all aspects of the drilling, logging, cas-
ing, cementing, stimulation, and initial testing of a well. This information
is necessary for the regulatory agency to determine whether or not wastewater
injection should be allowed. It also provides the well operator and the reg-
ulatory agency with a record of the well as a basis for interpreting the
276
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cause of any operational difficulties that may arise and for making future
engineering decisions. The Ohio River Valley Water Sanitation Commission
(1973) provides an example of a well completion report form.
DESIGN EXAMPLES
Numerous examples of injection well design appear in the literature,
including those given by Baffa, 1969; Barraclough, 1966; Batz, 1964; Bayazeed,
1971; Bergstrom, 1968; Black, Crow and Eidsness, 1972; Brown and Spalding,
1966; Davis and Funk, 1974; Dean, 1965; DeRopp, 1951; DeWitt, 1960; Donaldson,
1972; Foster, 1972; Goolsby, 1971; Hartman, 1966, 1968; Herndon, 1970; Hund-
ley and Matulis, 1962; Klotzman and Veir, 1966; Leenheer and Malcolm, 1973;
Luff, 1960; Lynn and Arlin, 1962; MacLeod, 1961; McChem and Garnet, 1967;
Ostroot and Donaldson, 1970; Paradiso, 1956; Talbot, 1968; Tucker and Kidd,
1973; Veir, 1967; and Warner, 1972. A comprehensive and well-indexed annotated
bibliography has been published by the U. S. Geological Survey covering the
period prior to 1971 (Rima, et. al. , 1971).
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REFERENCES
CHAPTER 7
American Petroleum Institute. "Specification for Casing, Tubing, and Drill
Pipe. 33rd edition. API Std. 5A. Dallas, Texas. 1975.
American Petroleum Institute. "Specifications for Oil-Well Cements and Cement
Additives." API Standard 10A. Amer. Petroleum Institute. Dallas,
Texas. 1975-a.
American Petroleum Institute. "Environmental Protection Laws and Regulations
Related to Exploration, Drilling, Production, and Gas Processing Plant
Operations." API Bulletin D18. API, Dallas, Texas. March, 1975-b.
American Petroleum Institute. "Casing Centralizers." API Specification 10D.
API, Dallas, Texas. 2nd ed. February, 1973.
American Petroleum Institute. Problems in the Disposal of Radioactive Waste
in Deep Wells. A Report Prepared by the Subcommittee on Disposal of
Radioactive Waste. API, Dallas, Texas. October, 1958.
American Petroleum Institute. Selection and Evaluation of Well-Completion
Methods. API Bull. D6, Division of Production, Dallas, Texas. 1955.
American Petroleum Institute. Survey Report on Casing-String Design Factors.
API, Dallas, Texas. 1955-a.
American Petroleum Institute. "Casing Landing Recommendations." API Bulletin
D7. Dallas, Texas. 1955-b.
Baffa, J. L. "Injection Well Experience at Riverhead, New York." Journal
American Water Well Association. January, 1969. pp. 41-46.
Barlow, A. C. "Basic Disposal-Well Design." in Underground Waste Management
and Environmental Implications. T. D. Cook, ed. Amer. Assoc. Petroleum
Geologists Memoir 18, AAPG, Tulsa, Oklahoma. 1972. pp. 72-76.
Barraclough, J. T. "Waste Injection Into a Deep Limestone in Northwest Flor-
ida." Ground Water. Vol. 4, No. 1. 1966. pp. 22-24.
Batz, M. E. "Deep Well Disposal of Nylon Waste Water." Chemical Engineering
Progress. Vol. 60, No. 10. 1964. pp. 85-88.
278
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Bayazeed, A. F., and Donaldson, E. C. "Deep-Well Disposal of Steel Pickling
Acid." presented at 46th Annual Fall Meeting of the Soc. of Pet. Eng.
of AIME, New Orleans, La., Oct. 3-6. Paper No. SPE 3615. 1971. 5 pp.
Bergstrom, R. E. "Feasibility of Subsurface Disposal of Industrial Wastes
in Illinois." Illinois Geological Survey Circular 426. 1968. 18 pp.
Black, Crow & Eidsness, Inc. Engineering Report on Modification to Deep-Well
Disposal System. Effect of_Mojritoring_We! Is and Future Monitoring Re-
quirements for Sugar Cane Growers Coop, of Florida, Belle Glade, Palm
Beach County, Florida. Engr. Report Project No. 387-71-01. 40 pp.
Blum, H. "Casing Program." Fundamentals of Rotary Drilling. The Petroleum
Engineering Publishing Company, Dallas, Texas. 1959.
Brown, R. W., and Spalding, C. W. "Deep Well Disposal of Spent Hardwood
Pulping Liquors." Water Pollution Control Federation. June, Vol. 38,
No. 12. 1966. pp. 1916-1925.
Buzarde, L. E., Kastor, R. L., Bell, W. T., and DePriester, C. L. Production
Operations Course I - Well Completions. Society of Petroleum Engineers.
1972. pp. 66-109.
Campbell, M. D., and Lehr, J. H. Water Well Technology. McGraw-Hill Book
Company, New York. 1973. 681 pp.
Clark, J. B. "A Hydraulic Process for Increasing the Productivity of Wells."
Transactions Am. Inst. of Mining Engineers. Vol. 186. 1949. pp. 1-3.
Craft, Holden, & Graves. Well Design: Drilling and Production. Prentice-
Hall, Inc., Englewood Cliffs, New Jersey. 1962. pp. 101-157.
Davis, K. E., and Funk, R. J. "Control of Unconsolidated Sands in Waste-Dis-
posal We11s." in Underground Waste Management and Environmental Impli-
cations. T. D. Cook, ed. Am. Assoc. Petroleum Geologists Memoir 18.
A.A.P.G., Tulsa, Oklahoma. 1972. pp. 112-118.
Dean, B. T. "Design and Operation of a Deep Well Disposal System." Water
PoJJution CpntroJ Fede_ratio_n_ Journal. Vol. 37, No. 2. 1965. p~p."245-
254.
DeRopp, H. W. ''Chemical Waste Disposal at Victoria, Texas. Plant of the Du-
Pont Company," Sewage and Industrial Wastes. Vol. 23, No. 2. 1951.
pp. 194-197. """ " "
DeWitt, W. Geology of the Michigan Basin with Reference tp_ Subsurface Disposal
of Radioacti ve Waste. Atomic Energy Commission Report TFI-771. 'I960.
Too pp
Donaldson, L. C. "!)ee;> Well Disposal of Liquid Mine Waste." I). 5. Bureau
of Mines I . C. 70. pp. W~(A.
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Foster, J. B., and Goolsby, D. A. "Construction of Waste-Injection Monitor
Wells Near Pensacola, Florida." Florida Bureau Geologic Information
Circular, No. 74. 1972. pp. 34.
Gatlin, Carl. Petroleum Engineering, Drilling and Well Completions. Prentice
Hall, Inc., Englewood Cliffs, N. J. 1960. 341 pp.
Goolsby, D. A. "Hydrogeochemical Effects of Injecting Wastes into a Limestone
Aquifer Near Pensacola, Florida." Ground Water. Vol. 9, No. 1. 1971.
pp. 13-19.
Halliburton. Handbook of Applied Rheology Section One, Newtonian Fluids.
Halliburton Company, Duncan, Oklahoma. 1963.
Hartman, C. D. "Deep Well Disposal at Midwest Steel." Iron and Steel Engineer-
ing. No. 12. 1966. pp. 118-121.
Hartman, C. D. "Deep Well Disposal of Steel-Mill Wastes." Journal Poll. Con-
trol Fed. Vol.40, No. 1. January, 1968. pp. 95-100.
Herndon, J. "Deep-Well Disposal - Prerequisites, Priorities and Practices"
presented at 17th Annual Southwestern Petroleum Short Course, Texas
Tech University, Lubbock, Texas, April 16-17, 1970. 1970. 17 pp.
Howard, G. C.5 and Scott, P. 0. "An Analysis and the Control of Lost Circu-
lation." Petroleum Transactions. Am. Institute of Mining Engineers.
Vol. 192. 1951. pp. 171-182.
Hundley, C. L., and Matulis, J. T. "Deep Well Disposal of Industrial Waste
by FMC Corp." Indust. Water and Waste. September-October, 1962,
pp. 128-131.
Klotzman, M., and Veir, B. "Celanese Chemical Pumps Wastes Into Disposal Wells,
Oil and Gas Journal. Vol. 64, No.15. 1966. pp. 84-87.
Koenig, Louis. "Survey and Analysis of Well Stimulation and Performance."
Journal Am. Water Works Assoc. Vol. 52, No. 3. March 1960. pp. 333-350.
Leenheer, J. A., and Malcolm, R. L. "Case History of Subsurface Waste Injec-
tion of an Industrial Organic Waste." AAPG Gulsa, Oklahoma. 1973.
pp. 565-584.
Long, J. T. Engineering for Nuclear Fuel Reprocessing. Gordon and Breach
Science Pub., Inc., New York. 1967.
Luff, G. S. "Underground Waste Disposal for American Airlines, Inc." llth
Oklahoma Industrial Waste Conference Proceedings. Oklahoma State Univer-
sity, Stillwater, Oklahoma. 1960. pp. 71-80.
280
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Lynn, R. D., and Arlin, Z. E. "Anaconda Successfully Disposes of Uranium Mill
Waste Water by Deep Well Injection." Mining Engineering. Vol. 14, No. 7.
July, 1962. pp. 49-52.
MacLeod, I. C. "Disposal of Spent Caustic and Phenolic Water in Deep Wells."
8th Ontario Industrial Waste Conference Proc. 1961. pp. 49-58.
Mecham, 0. E., and Garret, J. H. "Deep Injection Disposal Well for Liquid
Toxic Wastes." American Society Civil Engineers Proceedings. Journal.
Construction Div. 1963. pp. 111-121.
Moore, P. L. Drilling Practices Manual. The Petroleum Publishing Company,
Tulsa, Oklahoma. 1974. 447 pp.
Ohio River Valley Water Sanitation Commission. Underground Injection of Waste-
waters in the Ohio Valley Region. ORSANCO, Cincinnati, Ohio. 1973. 63 pp.
Ostroot, G. W., and Donaldson, A. L. "Subsurface Disposal of Acidic Effluents."
presented at 1970 Evangeline Section Regional Meeting of the Society of
Petroleum Engineers of AIME, Lafayette, La., Nov. 9-10, 1970. Paper
No. SPE 3201. 1970. 6 pp.
Paradiso, S. J. "Disposal of Fine Chemical Wastes." in Industrial Waste Con-
ference No. 10, 1955 Proceedings. Purdue University, Engineering Ex-
tension Service 89.1956.pp. 49-60.
Petroleum Extension Service. Twelve Issue Training Series on Petroleum Explo-
ration and Development. Published in cooperation with the University of
Texas at Austin and the International Association of Drilling Contractors
1971-present.
Rima, Donald R., Chase, Edith B., and Myers, Beverly. "Subsurface Waste Dis-
posal by Means of Wells--a Selective Annotated Bibliography." U. S.
Geological Survey Water Supply Paper 2020. U. S. Gov't. Printing
Office, Washington, D.~C. 1971. 305 pp.
Smith, D. K. "Cementing." ^Spjnjjty of JL?_trpJ euni^_En_gi neers Mpnp_g_ra_ph Vgl_ume_J_.
Society of Petroleum Engineers of AlME, New York. 1976.
Talbot, J. S. "Some Basic Factors in the Consideration and Installation of
Deep Well Disposal Systems." W & S W. 1968. pp. R-2'l 3-R-219.
Trevorrow, L. E., Warner, D. L., and Steindler, M. j. Considerations Affect-
ing Deep-Well Disposal of Tritium-Bearing Low-Level Aqueous Waste from
Nuclear Fuel Reprocessing Plants. ANL-76-76, Arqonne National Labora-
tory, Arqonne, Illinois. March, 1977. 190 |>p.
T:J:MT, '.•,'. :.'. , and Kidti, '•'. F. Deep Wei! !)i spus.! 1 ;• A i abai^;.
'•.ur'.''•,•' y' Al ai)di".ii . : ...j i • c+i <] l:;'i, )'• i vet"', ; t.y r,\ ..., ri';::":,:
:>(•' i.iro'i We'll !.li si ](')•,, i ' f'r.ic'.i \ ,. ' Pro: rr-tii MT-, /'.h Indus-
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Warner, D. L. Deep-Hell Injection of Liquid Haste. U. S. Dept. of Health,
Education, and Welfare, Public Health Service Publication No. 99-WP-21
1965. 55 pp.
Warner, D. L. Survey of Industrial Waste Injection Wells. Vols. I and II.
U.S.G.S. Contract 14-01-0001-12280 (NTIS #AD-756-641). June, 1972.
282
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CHAPTER 8
PRE-INJECTION PREPARATION AND START-UP OPERATIONS
The period between the completion of injection well construction and
initiation of full-scale operation affords an excellent opportunity to under-
take several very important tasks. The well operator may run several types
of logs and final tests to obtain the data needed to establish the baseline
characteristics of the well. The operator can also use this time to instruct
his or her supervisory and operating personnel in all aspects of injection
well operation, as well as in proper procedures for dealing with both common
problems and emergencies. Finally, the well operator should also, at this
time, obtain any necessary authorization from state and federal regulatory
agencies. Only after he or she has done all this can the operator be ready
for full-scale injection operations.
PRE-INJECTION TESTING
After the well is cased but before injection operations start, there is
an opportunity for extensive testing of the proposed reservoir and of the mech-
anical elements of the well itself. The data thus derived will serve to iden-
tify problems in the condition of the well and in the injection interval, and
to provide baseline information on injection interval performance. During
such testing, minor quantities of treated wastewater may be injected to con-
firm the chemical compatibility of reservoir water and wastewator. Tracers
may be injected and monitored, and temperature and flow meter logs may be
run to define the zones into which injected fluids are initially entering.
The selection of these tests depends largely on the circumstances surrounding
each project.
•LnJ_§ŁtLyJ ty Testing
Initial pumping and/or injection tests for defining reservoir character-
istics are discussed in Chapter 3, and the advantages and disadvantages of the
two practices outlined. Eventually, injection testing will be needed, and
some testing is usually carried out before final well completion; then, if
necessary, the well may be stimulated to improve its capacity to accept in-
jected wastewater. Final injection testing is performed prior to full-scale
operation to define the baseline characteristics of the well and of the in-
jection interval. The water used for injection testing may be water extracted
during pumping of the injection interval, treated surface or ground water, or
treated wastewater. The choice of the water to be used for testing will de-
pend on the particular site conditions and also on regulatory constraints.
In cases where the injection interval is known to he or is suspected of being
water-sensitive, as discussed in Chapter 5, the use of water pumped from the
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injection interval should minimize the potential clay mineral reaction. How-
ever, the collected formation water should be monitored chemically during
storage to insure that chemical changes do not occur between the time the
water is withdrawn from the formation to be injected and the time it is used
in the testing operations. Some chemical stabilization may be required.
Where the injection interval is not water-sensitive, i. e., where it
does not contain reactive clays, treated surface water or ground water from
a production well can be used for testing. Such water is often used when it
is desirable to place a buffer of nonreactive water between the formation wa-
ter and the iniected wastewater.
Treated wastewater can also be used for testing and often is. However,
some state regulatory agencies may prohibit injection of any wastewater until
after final testing, the results of which are used to determine whether an
operating permit will be issued.
Injection tests are usually run in one of two ways. One method is
termed step testing, in which injection is initiated at a low rate, and that
rate is maintained until the injection pressure has stabilized. The rate is
then increased in steps, each new rate being maintained for the same time
interval as the first, until the maximum desired rate is finally reached.
Well-head pressure is continuously monitored during the entire injection per-
iod and after injection hasceased, until the well-head pressure has declined
to zero. It is advantageous to monitor bottom-hole pressure as well, since
this gives a direct measure of pressure losses in the well. Otherwise, only
calculated values can be obtained for these losses. Steady rate tests are
also used, in which injection is held at a constant rate until the injection
pressure is nearly constant. Injection is then stopped, and the pressure is
monitored until it declines to zero. Such a test may be run at only one rate,
the planned operating rate, or it may be repeated for several rates. Either
type of test is satisfactory for injectivity analysis. The step-injection
test is more efficient but the steady-rate test is more easily and reliably
analyzed. Quantative analysis of injectivity tests is presented in Chapter 4.
Logging Techniques
A variety of logging methods are available, as discussed in Chapters 4
and 9, for determining the characteristics of the well and of the injection
interval after well construction but prior to initiation of full-scale in-
jection.
Three types of logs that are discussed in Chapter 9 are particularly
useful for defining the zones that will receive the injected water; these are the
flow meter log, radioactive tracer injectivity log, and the temperature log.
When combined with injectivity tests, these tools can indicate the presence
of formation damage resulting from drilling mud invasion or other causes.
When formation damage is suspected, the well can be stimulated and the re-
sults checked by running the logs again.
284
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Baseline Data
After the tests described above and the last stages of clean-up of the
injection interval are completed, the final "baseline" data can be obtained.
Final bottom-hole temperature and static pressure should be recorded after all
clean-up operations have been completed, but before full-scale injection of
the wastewater stream. The start-up process should be of low volume, with all
data collected as often as is practical. Data obtained during this period are
critical to the well's future. Should any abrupt or unexpected variation in
operating characteristics occur, the injection start-up should be curtailed
immediately to allow for an investigation to establish the probable cause of
variation and indicated procedures for renewed start-up.
OPERATING PROGRAM
The operating program for an injection system should be adopted to the
geological and engineering properties of the injection interval and to the
volume and chemistry of the waste fluids (ORSANDO, 1973). The geological and
engineering properties of the injection interval are defined during construc-
tion and testing, and the final operating program is.then approved by the regu-
latory agency.
Injection rates and pressures must be considered jointly, since the
pressure will usually depend on the volume being injected. Pressures are lim-
ited to values that will prevent damage to well facilities or to the confining
formations. The maximum bottom-hole injection pressure is commonly specified
on the basis of well depth. It may range from about 0.5 to 1.0 psi per foot
of well depth, depending on the geologic conditions, but it is seldom allowed
to exceed about 0.8 psi per foot of depth.
Experience with injection systems has shown that an operating schedule
involving rapid or extreme variations in injection rates, pressures, or waste
quality can damage the facilities. Consequently, provision should be made for
shut-off in the event of hazardous flow rates, pressure, or waste quality
fluctuations.
0Łe_ra_t_i_rH3 Procedures
Wastewater injection well systems are normally operated by technicians,
with supervision by professional engineers or scientists. Because such sys-
tems can be complex, and because the operating personnel will usually be in-
experienced in injection well operation, all details of the system's operat-
ing procedures should be documented as thoroughly as possible? in an operator's
manual. The consultants employed to design and supervise construction of the
system should prepare such a manual in cooperation with the well operator's
supervisory-level personnel. Since the operati'K; procedures will be unique
to each system, no attempt will be made here to specify the contents in de-
tail. However, some of the essential subject mo!.tor would include instructions
relatinn to the sources and competition of the wastewdter streams to be handled,
to the nature and operation of pro-injection wastewater treatment systems, to
monitoring procedures, to regulatory requirements, and to any emergency pro-
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cedures. It is common to provide training sessions to educate operating
personnel when a new system is to be put into operation.
Contingency Plan
A plan should be developed by the well operator and approved by the
state regulatory agency for an alternative waste management procedure if the
injection well should become inoperative or if it needs to be shut down. Such
a plan requires the availability of standby facilities, which could be a
standby well, holding tanks or ponds, or a waste treatment plant.
Full-Scale Operations
The transition from the last stage of development to full-scale operation
should be gradual. The disposal operator must recognize that, as the pressure
front and the leading edge of the effluent radiate outwards, exploration and
development are a continuous process.
When waste injection into the subsurface is begun, the operator immedi-
ately incurs an obligation. The requirements of knowing "what it is," "where
it is," and "what it is doing," are not relieved until the project is both
chemically and hydrodynamically inactive. This may be a period of months,
years, or decades after the cessation of injection.
PROBLEMS ENCOUNTERED DURING START-UP
Compatibility of New Wastewater Streams
A tight screening policy is necessary when any new waste streams are
added to the injection well system (Veir, 1967). It should be re-emphasized
here that any new waste resulting either from a new process or from a process
change must first be subjected to compatibility tests that utilize samples of
"design" wastewater (as discussed in previous chapters). If compatible, these
streams are then routed to the injection well system. If testing shows that
these wastes are not compatible, however, further testing should be performed
to isolate the particular stream or component causing the sample to fail the
compatibility test. If means cannot be found to make a given stream compatible,
an alternate disposal route for the waste must be used. Process wastes are
frequently found to be incompatible "as received." However, pH alteration or
treatment with other wastes will frequently render the waste in question com-
patible with the "design" wastewater.
The importance of compatibility tests should not be underestimated. An
example of incompatibility between an injected fluid and the receiving reser-
voir occurred when a new injection well system was installed and shut-in pend-
ing the start-up of a new plant (Davis and Funk, 1974). During plant con-
struction, the transfer lines to the injection well were pressure-tested with
fresh water, but were not drained. When the well was put into service, the
fresh water was displaced into the well, causing extensive formation damage
due to the hydration of water-sensitive clays, The result was a $250,000,
6,000-foot hole in the ground.
286
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Clogging
According to Brown and Spalding (1966), one common start-up problem
involves clogging which results from bacterial growth caused by drilling
fluid and. water that entered the well during the construction, testing, and
review periods. Biocides can aid in preventing such problems, especially
if wastewater injection is not begun within a few days of the completion and
fitting of the injection well.
Another possible problem area is illustrated by West's description (1972)
of one of the early problems the Anaconda Company experienced during injection
of uranium-mill effluent in New Mexico. After an initial 90-day test indicated
that injection was feasible at a rate of approximately 400 gpm under gravity
flow, and that the upper aquifers containing potable ground water did not show
any indications of contamination, state and federal agencies granted Anaconda
permission to use the well for operational injection, provided the injection
well was operated with the injection head lower than land surface, i. e., by
gravity flow only. Problems developed, however, soon after injection began,
when clogging of the well screens and of the injection interval decreased
the design input of 400 gpm to 125-250 gpm with an accompanying rise of water
level to near land surface.
One cause of the decrease in injectivity was related to low levels in
the tailings pond, which picked up* fine-grained sediment and overloaded the
on-line decanter, allowing entry to the injection well, and subsequently clog-
ging the screens and the injection interval. Another suspected cause com-
pounded the initial problems: wastewater quality varied significantly during
the early years of injection, which may have created unexpected compatibility
problems. In later years, the wastewater quality was normalized, and tailing
ponds were monitored to avoid low levels and the resultant introduction of
fine-grained material.
Routine Checks
Although a properly designed and maintained injection well system should
give years of reliable service, reliable records and routine checks on the
system's conditions are very important. Inconsistency between a well's actual
condition and the condition reported by instruments, records, and operating
personnel reports, for example, can cause unnecessary expenditures. In some
cases, incorrect or inadequate records can cause the workover costs to exceed
the new installation costs. One such experience was with a company that had
purchased a small chemical plant with two injection well systems (Davis and
Funk, 1974). Since the title and the responsibility for the wells were chang-
ing hands, the state required that a series of tests be performed to insure
the condition of the wells and to obtain information needed to bring the exist-
ing records up to date. The original cost, estimate was $10,000 for both sys-
tems. However, when these wells were entered, the casino on one well was so
bcidly damaged that the well had to be plugged hack and recor::p1 eted. The other
well was completed sonic 200 feet shallower than was shown in the records.
Thus, the actual cost to put the wells back into service was almost $50,000.
-------
Most regulatory agencies require the well operator to keep periodic
operating records. Start-up data, which describe the initial operating
conditions, are especially important since they will serve as a basis for com-
parison with later data. Figures 8-1 and 8-2 are typical examples of the
formats used.
STATE REQUIREMENTS FOR APPROVAL OF OPERATIONS
Walker and Cox (1976) suggest that the variation in details of well
operation between individual wells limits the extent to which state control
measures lend themselves to formalization as explicit provisions. Thus, in
the majority of cases, regulatory procedures do not set forth detailed stan-
dards, but rather require that all aspects of operation be subject to approval
by the appropriate regulatory agency.
However, formal controls do include specific provisions in some cases
in some states. The Nebraska Environmental Control Council (1974), the Michi-
gan Department of Natural Resources (1972), the Oklahoma Water Resources
Board (1972), and the Texas Water Quality Board (1972) have specific regula-
tory provisions relating to operation. The provisions should be reviewed in
detail, but, in general, they emphasize many of the topics considered in this
and other chapters of this text. Basically, the states emphasize
1. Procedures for operation relating to anomalous behavior of the
well;
2. Statements requiring the elimination or correction of leaks or
losses of fluids and pressure;
3. Exclusion of operations that may cause or create a condition
endangering public health or welfare;
4. Requirements for "adequate" equipment, and installations for
"appropriate" testing and monitoring of the operation;
5. Requirements that wastes shall be "treated" prior to injection,
unless otherwise authorized;
6. Requirements for the collection of records or reports, forms,
charts of operating pressures, of rates of injection, of types
and volumes of fluids injected or withdrawn and their submission
monthly or at other specified intervals;
7. Requirements that wastes shall be treated and stored before their
injection in such a manner to avoid ground water pollution:
8. Requirements for filing requests for change of status before
rework operations are commenced; and
9. Requirements that volumes of specific wastes, injection rates,
and pressures shall not vary from those specified in the original
state approval specifications.
288
-------
I. OPERATING PERIOD
Month Year
II. WELL OPERATOR
Name
2. Address
3. City State
4. Phone number
5. Permit number
III. SUMMARY OF OPERATIONAL DATA
A. Injected Volumes
1. Maximum daily volume specified in permit gal/day
2. Maximum daily volume during operating period gal/day
3. Present average daily volume gal/day
4. Total volume injected to date gal.
B. Injection Rate
1. Maximum injection rate specified in permit gpm
2. Maximum injection rate during month gpm
3. Average injection rate during month __ _ gpm
C. Injection Pressure
1. Maximum well-head injection pressure specified in permit
psi
2. Maximum well-head injection pressure during month osi
3. estimated average well-head injection pressure durinu month
[•'si
IV. DETAILED OPERATIONAL DATA (supply detailed well oprn-j tint; recur:! to
accompany thi s report.) .
V. INSTRUCTIONS
A. i,irh operator of r'iii in.JIM tion project sh,;! ! tuf', i'.
' h i ••• form not. Id tor Muni 1.hf l()th d: ';'!-;'
-------
FIGURE 8-1. Continued
B. If several wells are utilized, report each one separately.
C. Fill in reverse side of form relative to daily injection practices.
D. Continuous recording charts will be made available upon request.
E. All operational problems, changes in injection system or wastes are
to be reported when they occur.
290
-------
CONTINUOUS
OPERATING PERIOD
:t,art
End
Length of
Period
ine Date Time 1 (days & hrs) 1 Averi Max
2. INJECTION
RATE (GPM)
)N
>M)
<
3. PRESSURE (PSI)
Well -Head Injection
Max
Min
Estimated
Average
Casing
Tubing
Annul us
4. FLUID INJECTED (GAL)
Operating
Period
Total
Cumulative
Report items 2 and 3 for each day of operating periods that exceed one day.
FIGURE 8-2. INJECTION WELL OPERATING RECORD (ORSANCO, 1973)
-------
CHAPTER 8
REFERENCES
Brown, R. W., and Spaulding, C. W. "Deep-Well Disposal of Spent Hard Wood
Pulping Liquors." Journal Water Pollution Control Fed. Vol. 38. 1966.
pp. 1916.
Davis, K. E., and Funk, R. J. "Subsurface Disposal of Industrial Waste."
Ind. Water Eng. Sept. - Oct. 1974. pp. 14-17.
Michigan Department of Natural Resources. "General Rules Governing Mineral
Well Operations." June, 1972.
Nebraska Department of Environmental Control. "Rules and Regulations for
the Control of Disposal Wells to Protect Groundwater and Other Subsur-
face Resources of the State of Nebraska." June, 1975.
Ohio River Valley Water Sanitation Commission. Underground Injection of Waste-
Waters in the Ohio Valley Region. ORSANCO, Cincinnati, Ohio. 1973.
Texas Water Quality Board. "Subsurface Waste Disposal in Texas." Agency
Publication No. 72-05. February, 1972.
Veir, B. B. "Celanese Deep-Well Disposal Practices." Proc. 7th Ind. Water
and Waste Conf. Univ. Texas. June 1-2, 1967. pp. 111-125.
Walker, W. R., and Cox, W. E. Deep Well Injection of Industrial Wastes:
Governmental Controls and Legal Constraints. Virginia Water Resources
Research Center, Blacksburg, Virginia. 1976. 163 pp.
West, S. W. "Disposal of Uranium-Mill Effluent by Well Injection in the
Grants Area, Valencia County, New Mexico." U.S.G.S. Prof. Paper 386-D.
1972. 28 pp.
292
-------
CHAPTER 9
INJECTION WELL MONITORING
The principal means of surveillance of wastewater injection that is pre-
sently practiced is monitoring at the injection well of the volume, flow rate,
chemistry, and biology of the injected wastewater and of the injection and
annulus pressures (Figure 9-1). To some this apparently seems inadequate.
However, if all of the necessary evaluations have been made during the plan-
ning, construction, and testing of the well, then this may be a satisfactory
program, when combined with periodic inspection of surface and subsurface fac-
ilities. This is because, as pointed out by Talbot (1972), the greatest risk
of escape of injected fluids is normally through or around the outside of the
injection well itself, rather than from leakage through permeable confining
beds, fractures, or unplugged wells.
The purpose of monitoring the volume and chemistry of injected waste-
water is to allow for estimates of the distance of wastewater travel, to al-
low for interpretation of pressure data, and to provide a permanent record.
This record is needed as evidence of compliance with restrictions, as an
aid in interpretation of well behavior, in well maintenance, and as a pre-
caution in the event that a chemical parameter should deviate from design
specifications. Some characteristics that have been monitored continuously
are flow, suspended solids. pH, conductance, temperature, density, dissolved
oxygen, and chlorine residual. Complete chemical analyses are frequently
made on a periodic basis on composite or grab samples. Because bacteria may
have a damaging effect on reservoir permeability, periodic biological analy-
sis of some wastewaters may be desirable to insure that organisms are not
being introduced.
Injection pressure is monitored to provide a record of reservoir per-
formance and as evidence of compliance with, regulatory restrictions. Injec-
tion pressures are limited to prevent, hydraulic fracturing of the injection
reservoir and confining beds, or damage to well facilities. As with flow
data, injection pressure should be continuously recorded.
Pressure fall-off data collected after any extended period of continu-
ous operation can be used to check the performance of the reservoir as com-
pared with its original condition. However, it should be rioted that, the time
'u.-ile u* i.ontinuous recorders is no* generally adequate f()r providing data
'iu>'in<.! the early period of a pressure U-. ll-filf tost, so the continuously re-
i. 01 ded daf.i will probably 'ii-o'i to he su;>pl o^eof o'.i v;iih additional ohserva-
'i\i or f f 11 I - o' f can be periodically !''ea'.ur
-------
FRESH-WATER-BEARING
SURFACE SANDS AND
GRAVELS
IMPERMEABLE SHALE
o ,
CONFINED FRESH-WATER
BEARING SANDSTONE
IMPERMEABLE
SHALE
PERMEABLE SALT-WATER-
BEARING SANDSTONE
INJECTION HORIZON
IMPERMEABLE SHALE
, PRESSURE GAGE
*V WELLHEAD PRESSURE
PRESSURE GAGE
SURFACE CASING SEATED
BELOW FRESH WATER AND
- CEMENTED TO SURFACE
INNER CASING SEATED IN OR
ABOVE INJECTION HORIZON
AND CEMENTED TO SURFACE
INJECTION TUBING
ANNULUS FILLED WITH
NONCORROSIVE FLUID
PACKERS TO PREVENT FLUID
CIRCULATION IN ANNULUS
OPEN-HOLE COMPLETION IN
COMPETENT STRATA
FIGURE 9-1. SCHEMATIC DIAGRAM OF AN INDUSTRIAL WASTE IN-
JECTION WELL COMPLETED IN COMPETENT SANDSTONE
(MODIFIED AFTER WARNER, 1965).
294
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a piezoelectric gage. Bottom-hole gages can give a more accurate reading of
injection pressure at the formation face than can be obtained by measuring
pressure at the surface and computing the bottom-hole pressure.
Figure 3-12 is an example of the pressure response that would ideally
be expected during a period of continuous injection. Pressure increase
through time should be linear on a semilogarithmic scale, after an early per-
iod of adjustment.
In contrast with this ideal behavior, Figure 9-2 shows the injection
pressure history of a wastewater injection well completed in a carbonate
reservoir. Two marked periods of pressure decline are shown, one in 1967-68
and one in 1970. The explanation for this is believed to be that the waste-
water being injected, initially an acid solution, reacted with the carbonate
reservoir to increase the permeability and thus decrease the injection pres-
sure. The period of gradual pressure increase during 1969-1970 is probably
the normal buildup following this initial period of permeability increase.
In 1970, the wastewater composition was changed to include a second acid
stream. This new stream apparently caused additional permeability increase
and a temporary reduction in injection pressure, after which the expected
pressure buildup resumed.
Figure 9-3 shows the plots of two pressure fall-off tests performed in
an injection well of the Monsanto Company, Pensacola, Florida. This well is
also constructed in a carbonate aquifer. One test was made in November 1967,
before injection of an acidic wastewater stream began. The other test was
performed in January 1969, after the acidic wastewater had been injected
for nine months. The second test shows a much slower rate of fall off, indi-
cating an increased permeability in the vicinity of the well bore caused by
a reaction of the acidic wastewater with the carbonate aquifer. This con-
clusion is substantiated by an increase in the injection index for this and
another well during the same time period, as shown in Figure 9-4.
Some other possible causes of deviation from the ideal response are the
presence of hydrologic barriers or conduits, leaky confining beds, and per-
meability reduction from suspended solids, chemical reactions, etc. The
variety of factors that may influence well behavior indicates the need for
maintaining an accurate, detailed well history so that the probable cause of
any unusual performance can be deduced and the appropriate action taken.
Pressure in the casing-tubing annul us is monitored to detect any changes
that might indicate leakage through the injection tubing or the tubing-casing
packer. When a packer is used, three different operational procedures are
possible. If fluid in the casing-tubinq annulus is not pressurized, then the
pressure would be expected to be zero. However, it, often will not be, be-
cause of effects such as expansion of injection tubing and thermal expansion
or contrvu.tion of the fluid ^n the annulus. If fluid in the annulus is pres-
surized, it. may he kept either below or above.1 the pressure in the injection
tubing. In any of the three cases, leakaqr is indicated by an abnormal chan'ie
in the cinnulus fluid pressure.
-------
800
600
cn
o_
400
a.
a:
IX)
to
CTl
en
UJ
ir
200
1967
1968
1969
YEAR
1970
1971
FIGURE 9-2. PRESSURE HISTORY OF A WELL INJECTING INTO A
CARBONATE AQUIFER.
-------
80
UJ
UJ
u.
UJ
-i
UJ
LU
O
IOC
120
140
160
180
200
O
O
10
O
JAN. 1969
"0= 975 gpm
O
O
O
O
O
NOV. 1967 /
0 = 950 gpm
O
I
100
TIME, MINUTES
1000
10,000
SEMILOGARITHMIC PLOT OF TWO PRESSURE FALL-OFF
TESTS MEASURED IN AN INJECTION WELL OF THE
MONSANTO COMPANY, PENSACOLA, FLORIDA (GOOLSBY,
1971).
-------
18
x
LU
Q
^g
*vO •
CO f—
o
LU
16
14
12
10
8
RATE "A"-I- RATE " B"
INJECTION INDEX =
&P = BOTTOM - HOLE PRESSURE INCREASE
1963
1964
1965
1966
1967
1968
1969
FIGURE 9-4. MONTHLY AVERAGE INJECTION INDEX OF TWO INJECTION WELLS OF
THE MONSANTO COMPANY, PENSACOLA, FLORIDA (GOOLSBY, 1971).
-------
Other methods of injection well monitoring also deserve mention. The
corrosion rate of well tubing and casing may be monitored by use of corrosion
coupons inserted in the well. Corrosion coupons are weight-loss specimens
of the same metal as the tubing or casing. They are carefully cleaned and
weighed before exposure, exposed for a carefully measured period of time,
and then removed, cleaned, and reweighed. The weight was divided by the
specimen area and time of exposure gives the corrosion rate, usually in mills
per year.
A conductivity probe may be used to detect a change in the chemistry
of the fluid in the casing-tubing annulus. In wells with packers, the con-
ductivity probe can be used to detect tubing leaks, and in wells without
packers to detect shifts in the interface between the injected fluid and the
casing-tubing fluid. Another technique that has been used to monitor the
casing-tubing annulus is continuous cycling of the annulus fluid and analysis
of the return flow for evidence of contamination by wastewater.
PERIODIC INSPECTION AND TESTING
Sufficient incidents have occurred in the past to emphasize the need
for periodically inspecting or testing the subsurface facilities of injection
wells, particularly when chemically reactive wastes are being injected. The
most frequently reported problem'has been corrosion of tubing and/or casing.
Several cases have been reported in which portions of tubing or casing have
failed by corrosion and caused temporary or permanent shutdown of the well.
There may also be reason to examine the well bore to check for the location
of zones of wastewater entrance, enlargement due to chemical reaction, the
location and orientation of induced fractures, build up of precipitates or
filtered solids, etc. Examples are available of wells that have been aban-
doned or modified because of borehole enlargement that led to collapse of
the borehole or damage to the casing or cement near the bottom of the casing
string.
Methods of inspection of casing, tubing, cement and the well bore are:
1. Pulling of tubing and visual or instrumental
inspection.
2. Inspection of casing or tubing in place, using
electromagnetic logs.
3. Inspection of casing, tubing in place, or the
well bore with caliper or televiewer logs.
4. Pressure testing of casing.
I). Inspection of casinq cement with cenent bond
I ogs.
(>. Inspection of Lcisiru] crnirnt, or the well bore with
inject ivity or tempertiture pro'iles or other uppro-
[ifia'c1 loqs.
-------
The process of pulling and inspecting tubing is self-explanatory.
Mechanical methods are available, for example, for inspection of lined steel
tubing for flaws in the lining. Individual joints of tubing can be pressure
tested at the surface for leakage.
Electro-magnetic down-hole casing or tubing inspection services are
provided by oil field service companies. These logs indicate, by virtue of
the electromagnetic response of steel pipe, the relative pipe thickness.
Thin areas may indicate corrosion or other damage, either on the inside or
outside of the pipe. Another similar device relates surface currents induced
on the inside of tubing or casing to inside pipe diameter. Figure 9-5 illus-
trates a typical simultaneous Electronic Casing Caliper Log and Casing Inspec-
tion Log run in 7 in. OD casing. The wall thickness as measured by the Cas-
ing Inspection Tool is shown on the right. Casing collars are indicated at
6,412; 6,452; and 6,495 ft. The deflection to the right is caused by the
mass of the casing collars; the double response is due to the two-coil meas-
uring system. The Electronic Casing Caliper Log is shown on the left side
of the depth column. The single sharp deflection to the right at each collar
is caused by the natural separation that exists between casing joints. The
anomaly at 6,428 ft. is interpreted as a hole caused by external pitting cor-
rosion (McCullough Services, undated). Figure 9-6 is a similar type of log,
along with photographs of the casing that was pulled after running the log.
If such logs are run early in the life of the well, then runs that are made
later after the well has been in operation are more easily interpreted.
Mechanical caliper logs provide a record of the inside diameter of
pipe or borehole walls and may show intervals of pipe corrosion, borehole
enlargement, or borehole plugging at the formation face. Figure 9-7 shows
portions of a caliper log run before injection and after five years of in-
jection of an acidic wastewater into a limestone aquifer. The log indicates
considerable borehole enlargement as a result of dissolution of the lime-
stone by the injected acidic waste in the interval from 1500 to 1600 feet.
It would be reasonable to conclude that most of the wastewater entered that
interval.
Borehole televiewers provide an image of the pipe or borehole wall as
produced by the reflection of sound waves emitted from a sonde (Zemanek,
1970). The combination sound source and receiver is highly directional and
is rotated rapidly as the tool is moved up the hole. Thus, the hole is con-
tinuously scanned. The resulting information is displayed on an oscilloscope
and a film made of the scope display. The picture obtained depicts the well
bore as though it were split open and laid out for inspection. Figure g_8
illustrates the detail with which the borehole televiewer can indicate cas-
ing damage. Figure 9-9 depicts televiewer logs run in a well in the Piceance
Basin, Colorado, before and after hydraulic fracturing. The dark area in
the "after" log is a vertical hydraulic fracture (Bredehoeft, et. al., 1976).
Pressure testing can be used to detect casing leaks, and it is required
by law in many oil-producing states as a method of testing the integrity of
casing in new wells at the time that the casing is cemented into the borehole.
In such tests, a cement plug is left at the bottom of the casing during cem-
enting and allowed to harden. The interior of the casing is then subjected
300
-------
INSIDE DIAMETER (Inches) WALL THICKNESS (Inches)
6.1 6.2 6.3 .328 .408 .488
)
6400
HOLE'
6450
6500
TYPICAL SIMULTANEOUS ELECTRONIC CASING CALIPH?
AND CASING INSPECTION LOGS SUN IN ; INCH Oil CASING
{McCUl I OUGK SFRVICCS, UNDATFIl).
-------
PHASE SHIFT PHASE SHIFT
0° 360° 0° 100
CO
o
Joint '19—Bottom 3' severely corroded
with several small holes.
Joint -20 —Bottom two thirds of joint
severely corroded with several large
holes 1" to 2" in diameter. Bottom 2'
has extensive corrosion with numerous
small holes.
Joint -21 -Severely corroded over top
two thirds of joint.
FIGURE 9-6,
PIPE INSPECTION LOG AND PHOTOGRAPHS OF
CASING PULLED AFTER LOG WAS RUN TO VERIFY
THE LOG (SCHLUMBERGER, 1970).
-------
July 1966
September 1971
LU
UJ
U.
UJ
O
cc
r>
CO
O
LU
03
O.
ID
O
1400 r
1500
1600
1700
1
1400
1600
-
1900
1500
- 1600
1700
1800
1900
6
I
II 16
0 8 12 16 20 24 28
36
LU
LU
LU
QC
CO
O
-J
O
UJ
QD
X
t-
CL
UJ
DIAMETER, IN INCHES
DIAMETER, IN INCHES
PPL.-INJECTION A'i!) POST- INJTCTION CA1.1 PER LOGS FROM A
'.VAS7D/ATT.R INJFCTIO:; Wfl.l. AT p,r[.[,F GI.ADF, FLORIDA,
SMOWINfi SOLiiTIO",1 OF T;::' I. 1VFSTONF AQiJjF'FR 1 .\ TflF
1:7)0- to 1GOO-FT. ['ii'; I-V.'Ai HV ACIDIC MSTIUATLR
;:;;; A^:, CROK, A'J'.I i i::1-';; ss, in?/;.
-------
BOREHOLE TELEVIEWER
•*.
PERFORATIONS
4 SHOTS/ FT.
PHASED 120°
jjor ~: .^.*******K<^*«*--- -.7..^. ULU r AL»r\tK otnl
(DRILLED OUT)
CASING COLLAR
CASING INSPECTION
FIGURE 9-8. BOREHOLE TELEVIEWER LOG OF A SECTION OF CASING
PERFORATIONS, PACKER SEAT, AND CASING COLLAR
(SCHLUMBERGER, 1970).
304
-------
BEFORE
1045'i
AFTER
1051'
1057'
T.S.6
FIGURE 9-9. TELEVIEWER LOGS RUN BEFORE AND AFTER HYDRAULIC
FRACTURING OF A WELL IN THE PICEANCE BASIN,
COLORADO (BREDEHOEFT, ET. AL., 1976).
-------
to a specified amount of fluid pressure (0.2 psi per foot of casing in
Texas).' Rapid decline in pressure indicates leakage from the casing. Such
a test could also be performed periodically in operating wells by setting tem-
porary plugs or using packers.
The cement bond log is used to determine the quality of the casing-
cement bonding and to detect channels in the cement behind the casing, or to
detect damage to cement from high-pressure injection or chemical reaction.
The cement bond log is a continuous measurement of the amplitude of elastic
waves after they have traveled through a short length of pipe, cement, and
perhaps formation (Figure 9-10). The amplitude of the elastic wave is maxi-
mum in uncemented casing and will generally be lower as the degree of bonding
and integrity of the cement improves. Thus, the relative amplitudes of the
waves in different portions of a well can be interpreted to indicate the con-
dition of the cement and degree of bonding. Figure 9-11 shows portions of
a cement bond log from an acid wastewater injection well. It appears that
the casing in the vicinity of 1900 to 2000 feet is not bonded. The interval
from 2700 to 2800 feet, near the base of the casing, shows progressively bet-
ter bonding between the casing and cement. Figure 9-12 is an example of a
modern cement bond log, the Acoustic Cement Bond Log/Micro-Seismogram, which
consists of a pipe bond curve, formation bond curve, and the Micro-Seismogram.
An additional log, usually a gamma ray or neutron log, is run for depth con-
trol, since these logs can detect formation contacts behind casing and can be
compared with logs run before the well was cased. The figure shows intervals
of good bond, poor bond, and no bond. The basis for the interpretation of the
current cement bond logging devices is given by Walker (1968). Complications
that occur in the interpretation of cement bond logs are discussed by Fertl
et. al. (1974).
Some other possible inspection methods are flow-meter injectivity pro-
files, radioactive tracer injectivity profiles, and temperature profiles.
Flow meter profiles indicate the amount of flow from an injection well into
the permeable zones in adjacent formations. Measurement is made either con-
tinuously throughout the interval of interest or in increments that are iso-
lated by packers. In either case, the measuring device is a spinner-type
velocimeter. Only the location of exit of fluids from the well can be mea-
sured. The device does not detect fluid movement behind casing. Radioactive
tracer injectivity profiles are based on the injection of a radioactive tracer
and logging of the borehole with a gamma ray detector. The detector measures
concentrations of tracer, which indicate paths of tracer flow. The method
is useful in identifying permeable zones; locating casing, tubing, or packer
leaks; and in detecting flow channels behind casing. Temperature profiles
may indicate anomalies at points where injected fluids enter the receiving
formation or where they escape through casing or tubing leaks. Such anomalies
would most likely be detectable in wells where significant temperature con-
trasts exist between injected fluids and the aquifers.
Repetitive running of resistivity or radioactive logs may also be used
to locate the zones that are accepting injected wastewater. Resistivity logs
'Texas Railroad Commission rules.
306
-------
TRANS
REC.
CASING
BORE
HOLE
LIQUID
BONDED CEMENT
'/SHEATH/
SONIC PULSE
WAVE FRONT
FORMATION
- /
FIGURE 9-10. SCHEMATIC DIAGRAM OF A CEMLNT BOND LOGGING
TOOL IN A RORFHOLF (GROSMANGIN FT. AL . , I%1).
-------
FIGURE 9-11. PORTIONS OF A CEMENT BOND LOG FROM
AN ACID WASTEWATER INJECTION WELL.
-------
GAMMA
c -c
'3'. iOi
|
AMPUTUM
P.PE 63NC
fOSMtTON BONO
Poor Bond
MKM-KBMOttJUT UK
ZOO 'ZOO
i\
T «,."
a _-•
TOOL DATA
14 3
24 B1
20
2!
weight
100*
160'
340*
370*
CSSuiL- R.llmg
20.000 psi
JO.000 p;.i
PO.OOO psi
20.000 psi
Temperature Rating
325-F
325 F
325 F
3J5'F
RECOMMENDED MINIMUM CASING SIZE. ID: 3V Tool. 4', . 2 . Tool. J'i '
,,, 'Without Gnmmn Rny ' 'With Gnmmn Hay
• Literature SPE Pflpor cl/il i»ninu
FIGURE 9-12.
rXAMPLC OF AN ACOUSTIC CL'Ml'NT BOND I Or,/
M1CR05FISMOGRAM, SHOWING INTfRVAIS Of
GOOD BOND, POOR BOND, AND NO F-iONP I'WU.LX
1973, P. 87).
-------
are limited to the uncased portion of a well, but radioactive logs have been
used to locate a freshwater-saline water interface behind casing (Keys and
MacCary, 1973).
MONITORING WELLS
The subject of monitoring wells has been a controversial one in regu-
lation of wastewater injection. Such wells are routinely used in shallow
groundwater studies but are less frequently used in conjunction with waste-
water injection, for reasons that will be examined.
At least three hydrogeologically different types of monitor wells can
be and have been constructed, each with different objectives as shown below:
Nell Type
1. Constructed in receiving aquifer—
nondischarging
2. Constructed in or just above
confining unit--nondischarging
Objective
a. Obtain geologic data
b. Monitor pressure in receiving
aquifer
c. Determine rate and direction
of wastewater movement
d. Detect geochemical changes in
injected wastewater
e. Detect shifts in freshwater-
saline water interfaces
a. Obtain geologic data
b. Detect leakage through con-
fining unit.
3. Constructed in a freshwater
aquifer above receiving aquifer
a. Obtain geologic data
b. Detect evidence of fresh-
water contamination
Monitor wells constructed in the receiving aquifer are normally non-
discharging because a discharging well would defeat most of the purposes of
this type of monitor well. Also, the produced brines would have to be dis-
posed of. Although it is not normally necessary to monitor pressure in the
receiving aquifer except at the injection well, special monitor wells may be
desired where pressure at a distance from the injection well is of concern
because of the presence of known or suspected faults or abandoned wells that
may be inadequately plugged. The pressure response in a monitor well at such
locations would indicate the extent of danger of flow through such breaches
in the confining beds and possibly also indicate whether leakage was occur-
ring.
Constructing a monitor well or wells in the receiving aquifer is the
only direct means of verifying the rate and direction of wastewater movement.
More than one well will frequently be necessary to meet this objective, be-
cause monitor wells of this type only sample wastewater plumes that pass di-
rectly through the well bore; and non-uniformity in aquifer porosity and per-
310
-------
meability can cause the wastewater to arrive very rapidly or perhaps not at
all at a particular well. A single well might be satisfactory where aquifer
and fluid properties are such that it is judged most likely that wastewater
movement will be radial and reasonably uniform or where the objective is to
detect wastewater arrival at a particular point of interest. These same com-
ments apply to wells intended to detect geochemical changes in injected waste-
water. A difference is that a well for monitoring geochemical changes would
be placed near enough to the injection well so that the wastewater front will
arrive within a relatively short time, whereas, a well for detecting waste-
water arrival at a point of concern might be beyond the expected ultimate
travel distance of the wastewater.
A well intended to detect a shift in a freshwater-saline water inter-
face should be located either within that interface or in the freshwater por-
tion of the aquifer just beyond the interface. Because movement of this in-
terface will be in response to increased aquifer fluid pressure, rather than
to actual displacement by the wastewater front, detection of its movement
should be possible with a small number of observation wells, perhaps even a
single, properly located one. It is possible to estimate rates of movemen-t
for a particular case and to determine if a monitor well is likely to detect
such a shift. Monitoring would be for confirmation of the calculations and
to allow for revisions in regulation if unexpected results occur.
Negative factors should be considered in any case where deep monitor
wells are contemplated: monitor wells in the receiving aquifer may be of lim-
ited usefulness, and they provide an additional means by which injected waste-
water could escape from the receiving aquifer. In a number of cases, multiple
injection wells have been constructed at a site, one or more of which may be
standby injection wells. Standby wells can be used for monitoring of aquifer
pressure, and for sampling of aquifer water. However, if they have been oper-
ated or even extensively tested, their use for monitoring may be impaired.
Some examples of the use of observation wells in the receiving aquifer
are given by Goolsby (1971 and 1972), Kaufman (1973), Kaufman et. al. (1973),
Leenheer and Mel com (1973), Peek and Heath (1973), and Hanby and Kidd (1973).
Faulkner and Pa?cale (1975) updated the earlier reports by Goolsby and Kaufman
to provide the most comprehensive and detailed example available of injection
well monitoring.
For detection of leakage, the principal of using nondischarging monitor
wells completed in the confining beds or in a confined aquifer immediately
above the confining beds has been widely discussed but has been little used.
This type of well has the potential for acting as a very sensitive indicator
of leakage by allowing measurement of small chanoes in pressure (or water
level) that, accompany "leakage. A well of this type is best suited for use
where the confinimj unit is relatively thin and well-defined and where the
engineering properties of the two aquifers are within a range such that, pres-
.uro response in the ;::oni toreci aquifer will tie rapid if leakage occurs. Use
•,'f the i oncoDts outlined by Witherspoon ana
'ion of the nnssihi1 ities of success of thi'
i. i t.uot inn . in "lany actual cases, cOnfinirn; beds are1 several hundred ?o
era] thousand feet thick and do not ennfain aquifers suitable for S'./rh :
-------
itoring but several thousands of feet of interbedded aquitards and saline
water aquifers are present; in these cases, slow vertical leakage across the
aquitard immediately over the injection interval is not significant because
it can be predicted that there will be no measurable influence at the strati -
graphic level where freshwater or other resources occur.
Two good examples of the usefulness of monitoring an aquifer immediately
above the confining beds are provided by Kaufman et. al. (1973) and Leenheer
and Malcolm (1973). In the case described by Kaufman et. al., wastewater
leakage from the lower Floricfan aquifer through 150 feet of confining beds
into the upper Floridan aquifer was detected by geochemical analysis of water
from a monitor well constructed in the upper Floridan aquifer. No pressure
effects were noticed in this instance. Leenheer and Malcolm summarized a
case history in which leakage through the confining beds was detected first
by pressure increase in an overlying aquifer, and later confirmed by chemical
analysis which showed was.tewater contamination of water in the aquifer.
The type of monitor well most commonly in use is that which is completed
in a freshwater aquifer above the injection horizon for detecting freshwater
contamination. In a number of locations, this type of monitoring is provided
by wells that are a part of the plant's water supply system. In other cases,
the wells have been constructed particularly for monitoring and are not used
for water supply. Wells for detection of freshwater contamination should be
discharging wells because they then sample an area of aquifer within their
cone of depression. As previously mentioned, nondischarging wells are of
limited value for detection of contamination because they sample only that
water that passes through the well bore. Wells for monitoring freshwater
contamination should be located close to the anticipated sources or possible
routes of contamination, which are:
1. The injection well itself.
2. Other nearby deep wells, active or abandoned.
3. Nearby faults or fracture zones.
In the preceding discussion, it has been implied that separate wells
would need to be constructed for surveillance of aquifers and aquicludes at
different depths. This is not necessarily the case. Talbot (1972) shows how
the injection well itself can be adapted for monitoring of overlying aquifers,
and also how monitor wells may be constructed for surveillance of more than
one aquifer. Wilson et. al (1973) describe a case where the injection well
was modified as shown in Figure 9-13 for monitoring of two aquifers overlying
the injection zone.
Since the objectives for each of the types of monitoring wells discussed
are worthwhile ones, why are monitor wells not more widely used? The answer
to this question is that the potential benefits are often judged to be small
in comparison with the costs and negative aspects. Therefore, such wells may
not be voluntarily constructed by the operating companies nor required by
the regulatory agencies. In particular, monitor wells constructed in the re-
ceiving aquifer are often difficult to justify because such wells are the most
312
-------
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]3. GEOLOGIC COLUMN AND CONSTRUCTION OF A WASTEWATER INJECTION WELL AT
MULBERRY, FLORIDA, WHERE TWO AQUIFERS ABOVE THE INJECTION ZONE ARE
MONITORED THROUGH THE INJECTION WELL (WILSON ET. AL., 1973).
-------
expensive form of surveillance and may yield very little information that is
important for regulation. It can reasonably be concluded that monitor wells
should not be arbitrarily required, but should be used where local circumstan-
ces justify them.
OTHER MONITORING METHODS
A method of monitoring not so far mentioned is the sampling of springs,
streams, or lakes that could be affected by injection. There are few instan-
ces where such monitoring would be applicable; but, for example, where springs
originate along a fault within the area of pressure influence of the injection
well an increase in discharge rate or change in water quality could be an in-
dication of leakage of formation water along the fault in response to the in--
creased pressure from injection. Also, springs and gaining streams act simi-
larly to discharging wells in that they provide a composite sample of ground-
water over their area of influence; thus, they might reveal leakage from un-
known fracture zones or abandoned wells that connect a shallow groundwater
aquifer with the injection interval. In a similar way, lakes may be collect-
ing points for groundwater seepage or streams and may reflect quality changes
in shallow groundwater aquifers.
Surface geophysical methotis offer some limited possibilities for moni-
toring of wastewater injection. Barr (1973) discussed the feasibility of
monitoring the distribution of injected wastewater with seismic reflection.
Monitoring by seismic reflection depends on the existence of a sufficient
density contrast between injected and interstitial water, and no field trials
of monitoring by seismic reflection have been reported. Electrical resisti-
vity surveying could be useful for monitoring the movement of freshwater-sa-
line water interfaces or for detecting saline water pollution of freshwater
aquifers. Recent articles concerning detection of groundwater contamination
by resistivity surveying have been published by Stollar and Roux (1975), and
Klefstad, et. al. (1975).
Monitoring for earthquake occurrence is accomplished by use of a network
of seismometers placed in the vicinity of the injection well and in the vici-
nity of nearby faults along which seismic events might be triggered. Examples
of this form of monitoring are described by Raleigh (1972) and by Hanby and
Kidd (1973). In a case where earthquake stimulation is considered a possibi-
lity, seismic monitoring should begin before the well is operated to obtain
background data.
State Monitoring Requirements
Walker and Cox (1976) indicate that regulatory provisions with regard
to monitoring, like those concerning other elements of state control proce-
dures, exhibit a wide range of variation. The range extends from complete
absence of formal provisions to relatively detailed requirements concerning
monitoring procedures, with the general provision for such monitoring as is
required by the state regulatory agency falling somewhere in between. States
with specific monitoring provisions include Florida, Colorado, Michigan, Neb-
raska, Oklahoma, and Texas.
314
-------
The Florida Department of Pollution Control (1972) describes its state's
injection well monitoring policy:
"Adequate monitoring systems in disposal and fresh
water aquifers are required and shall be adequate
to insure knowledge of migration and behavior of
injected liquid wastes. Periodic reporting of the
following shall be required:
(1) Results of monitoring the volume,
chemical quality, temperature, and other
properties of the injected waste.
(2) Results of continuously monitoring
hydraulic pressures at the wellhead, in the
annulus, in the injection aquifer, in the
lowermost fresh water aquifer, and at other
places when required.
(3) Results of monitoring quality of water
in the fresh water aquifers at springs and
shallow observation wells and in the injection
aquifer at deep observation wells near the in-
jection we!1."
In Colorado, information submitted with an application for- an injection
well must include "... plans for monitoring injection pressures and forma-
tion pressures, i. e., injection wells and observation wells. (Colorado De-
partment of Health, 1974). In addition, this state has two rather unique
provisions contained therein: (the regulatory agency) may designate some
third party to utilize the monitoring system data developed by or for the
operation of the system." Also, regulations provide that "monitoring equip-
ment shall be operated and precautionary steps shall be undertaken after ter-
mination or abandonment for as long as the regulatory agency may reasonably
require which operation and steps shall be at the sole risk, cost, and ex-
pense of the person responsible for the disposal system.'1
Requirements of the other states mentioned previously are somewhat less
extensive. The Michigan Department of Natural resources (1972) requires mon-
itoring of ". . . operating pressures, rates of injection, types and volumes
"of fluids injected or withdrawn, and other pertinent information. . ."
The Nebraska Department of Environmental Control (1975) requires moni-
toring of effluent quality, injection rate and pressure, and pressure in the
casing-tubing annulus. The Oklahoma Water Resources Board (1973) requirements
include chemical and physical nature of waste material, injected amount of
waste material, density of waste (in pounds per cubic foot), injection-pump
pressure, annular pressure between tubing and production casing, and pressure
and fluid-quality reports from rnonitorinq wells where required.
Although not contained in formal rem,il ,it. ions, mon i tor i n
-------
"The Agency usually requires that a pressure gauge
be installed on the wellhead for monitoring the
pressure on the annul us between the injection
tubing and the protection casing. Should a leak
occur in the tubing or the packer seat, a pressure
increase on the annul us during injection would be
indicated by the gauge, and remedial action can
be initiated to correct the malfunction. A gauge
on the injecion tubing is also required to monitor
the surface injection pressure."
316
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REFERENCES
Barr, F. J., Jr. "Feasibility Study of a Seismic Reflection Monitoring System
for Underground Waste-Material Injection Sites." in Underground Waste
Management and Artificial Recharge. Jules Braunstein, ed.1973.
pp. 207-218.
Black, Crow, and Eidsness, Inc. Engineering Report on Modification to Deep-
Well Disposal System: Effect of Monitoring Wells and Future Monitoring
Requirements for Sugar Cane Growers' Cooperative of Florida, Belle Glade,
Palm Beach County, Florida. Engr. Rept. Proj. No. 387-71-01. 1972.
40 pp.
Bredehoeft, et. al. "Hydraulic Fracturing to Determine the Regional In-Site
Stress Field, Piceance Basin, Colorado." Geol. Soc. of Amer. Bulletin.
Vol. 87. 1976. pp. 250-258.
Colorado Department of Health. "Rules for Subsurface Disposal Systems."
January, 1974.
Faulkner, G. L., and Pascale, C. A. "Monitoring Regional Effects of High
Pressure Injection of Industrial Wastewater in a Limestone Aquifer."
Ground Water. Vol. 13, No. 2. 1975. pp. 197-208.
Fertl , W. H., et. al. "A Look at Cement Bond Logs." Journal of Petroleum
Technology. Vol. 26. June, 1974. pp. 607-617."
Florida Department of Pollution Control. "Revised Policy on Drainage and
Injection Wells." Technical Memo No. B-12. issued June 1, 1972.
Goolsby, D. A. "Geochenn'cal Effects and Movement of Injected Industrial
Waste in a Limestone Aquifer." in Underground Waste Management and
Enyj_rp_n_me_n_taJ_ _I_mpli cat ions. T. D. Cook, ed. Amer. Assoc. of Petroleum
Geologists Memoir IP. Tulsa, Oklahoma. 1972. pp. 355-367.
Goolsby, D. A. "Hydroqeocheniical Effects of Injecting Wastes into a Limestone
Aquifer near Pens;.u.ola, Florida." Ground Water. Vol. 9, No. "I. 1971.
pp. 13-19.
Gro v:ri nqi n , M. , e t. j ! .
lion of Borehole u.i
1961 . pp. 16:>-1 71 .
-------
Hanby, K. P., and Kidd, R. E. "Subsurface Disposal of Liquid Industrial
Wastes in Alabama—A Current Status Report." in Underground Waste
Management and Artificial Recharge. Jules Braunstein, ed. Amer. Assoc.
Petroleum Geologists, Tulsa, Oklahoma. 1973. pp. 72-90.
Kaufman, M. I. "Subsurface Wastewater Investigation, Florida." Amer. Soc.
Civil Engineers Proc. Journal Irrigation and Drainage Div. Vol. 99,
No. 1R1. 1973. pp. 53-70.
Keys, W. S., and MacCary, L. M. Location and Characteristics of the Interface
between Brine and Fresh Water from Geophysical Logs of Boreholes in the
Upper Brazos River Basin, Texas. U. S. Geological Survey Prof. Paper
809-B. 1973. 23 pp.
Klefstad, G., et. al. "Limitations of the Electrical Resistivity Method in
Landfill Investigations." Ground Water. Vol. 13, No. 5. 1975. pp. 418-
427.
Leenheer, J. A., and Malcolm, R. L. "Case History of Subsurface Waste Injec-
tion of an Industrial Organic Waste." in Underground Waste Management
and Artificial Recharge. Jules Braunstein, ed. Amer. Assoc. Petroleum
Geologists, Tulsa, Oklahoma. 1973. pp. 565-584.
McCullough Services. Casing Inspection/Casing Caliper Logging Service.
McCullough Services, Houston, Texas, undated.
Michigan Department of Natural Resources. "General Rules Governing Mineral
Well Operations." June, 1972.
Nebraska Department of Environmental Control. "Rules and Regulations for the
Control of Disposal Wells to Protect Ground Water and Other Subsurface
Resources of the State of Nebraska." June, 1975.
Oklahoma Water Resources Board. "Rules and Regulations." Chapter V., Sec.
530. 1973.
Peek, H. J., and Heath, R. C. "Feasibility Study of Liquid-Waste Injection
into Aquifers Containing Salt Water, Wilmington, North Carolina."
in Underground Waste Management and Artificial Recharge. Jules Braun-
stein, ed. Amer. Assoc. Petroleum Geologists. Tulsa, Oklahoma.
1973. pp. 851-878.
Raleigh, C. B. "Earthquakes and Fluid Injection." in Underground Waste
Management and Environmental Implications. T. D. Cook, ed. Amer.
Assoc. of Petroleum Geologists Memoir 18. 1972. pp. 273-279.
Schlumberger. Schlumberger Engineered Production Services. Schlumberger,
Houston, Texas. 1970.
Stellar, R. L., and Roux, P. "Earth Resistivity Surveys—A Method for Defin-
ing Groundwater Contamination." Ground Water. Vol. 13, No. 2. 1975.
pp. 145-150.
318
-------
Talbot, J. S. "Requirements for Monitoring of Industrial Deep Well Disposal
Systems." in Underground Waste Management and Environmental Implica-
tions. T. D, Cook, ed. Amer. Assoc. Petroleum Geologists Memoir 18.
1972. pp. 85-92.
Texas Water Quality Board. "Subsurface Waste Disposal in Texas." Agency
Publication No. 72-05. February, 1972.
Walker, Terry. "A Full Wave Display of Acoustic Signal in Cased Holes."
Journal of Petroleum Technology. 1963. pp. 17-22.
Walker, W. R., and Cox, W. E. Deep Well Injection of Industrial Wastes:
Government Controls and Legal Constraints. Virginia Water Resources
Research Center, Blacksburg, Virginia. 1976. 163 pp.
Warner, D. L. Deep-Well Injection of Liquid Waste. U. S. Dept. of Health,
Education, and Welfare, Public Health Service Publication No. 99-WP-21 ,
1965. 55 pp.
Welex. "Services." Service Memoranda 3. Welex, Houston, Texas. 1973.
Wilson, W. E., et. al . "Hydrologic Evaluation of Industrial-Waste Injection
at Mulberry, Florida." in Underground Waste Management and Artificial
..~,- .-~ ---- --^-- — ---- ---- _ ---- ---- — --
uuico LJIUUMO^CIM, cu. nine i . niiuc . re 11 u i cum ucu i uy I
Tulsa, Oklahoma. 1973. pp. 552-564.
Witherspoon, P. A., and Neuman, S. P. "Hydrodynamics of Fluid Injection."
in Underground Waste Management and Environmental Implications. T. D.
Cook, ed. Amer. Assos. Petroleum Geologists Memoir 18. Tulsa, Okla-
homa. 1972.
Zemanek, Joe, et. al . "Formation Evaluation by Inspection with the Borehole
Televiewer." Geophysics. Vol. 35, No. 2. 1970. pp. 254-269.
-------
CHAPTER 10
INJECTION WELL ABANDONMENT
Injection wells can be categorized according to their state of use or
non-use. In Table 1-1, Chapter 1, the categories of drilled wells include:
(1) drilled, but never used; (2) operating; (3) not operating, but unplugged;
and (4) not operating and plugged. All wells will eventually be permanently
removed from use for technical, economic or regulatory reasons. When a well
is permanently removed from use, it is plugged. A well that has been plugged
is considered abandoned. This chapter discusses the procedures for injection
well abandonment.
Abandonment may occur after many years of successful operation merely
because the well is no longer needed. At the other extreme, wells are occa-
sionally abandoned during construction, before there has ever been any injec-
tion, because of damage to the well or adverse geologic conditions. Usually,
however, the process of abandoning an injection well is thought of as begin-
ning when injection is permanently stopped. Because it is possible that a
well may need to be abandoned at any time, as a result of unforseen circum-
stances, Rudd (1972) recommends that tentative abandonment plans be made be-
fore injection begins.
Normally, abandonment consists of shutting-in a well, allowing some of
the built-up reservoir pressure to decline, and then plugging the well with
the appropriate materials. In some unusual cases, it might be desired to re-
move injected wastewater before plugging, either to reduce the reservoir pres-
sure more rapidly and/or to remove pollutants from the subsurface. An addi-
tional objective that has been suggested for wastewater removal is the recov-
ery of valuable components from the previously injected wastewater. So far
as is known, there has never been any extensive removal of injected waste-
water prior to abandonment for any of these purposes. However, if the need
to remove injected wastewater is considered a possibility, then a plan for
storing or disposing of the pumped wastewater should be available.
The purpose of plugging any deep well is to prevent mixing of fluids
from different geologic levels through an open well or hole, to prevent flow
of fluids from pressurized zones to the surface, and to maintain existing
pressures in the individual subsurface intervals. In the case of wastewater
injection wells, the principal objective is to provide for containment of the
injected waste within the interval selected for that purpose. However, com-
plete segregation of all water-bearing intervals should be achieved at the
same time.
320
-------
Rudd (1972) has suggested that wells should not be plugged immediately
so that they may be left open for observation until pressures have equalized
at a safe level and until the potentially harmful characteristics of the ef-
fluent have been attenuated. It would probably always be desirable to wait
for the reservoir pressure to decline to its preoperational level, or nearly
so, before plugging. However, the amount of pressure fall-off that is actually
achieved before plugging will be quite variable, since there may or may not
be other operating wells in the immediate vicinity,and there can be an urgent
need to proceed with the plugging of a well that has experienced an engineer-
ing failure.
There probably are some wastewaters that, as Rudd (1972) suggests,
should be observed until their harmful characteristics have been attenuated
before the injection well is plugged. However, many wastewaters will change
little, if any, with time and there are others whose chemical character is
such that any changes would be unimportant. Therefore, this observational
procedure should be applied only where it will yield significant information.
In spite of the extensive number of wells of all types that are plugged
each year, there is little published information concerning plugging, except
in the state regulations. States with extensive oil and gas resources have
long had regulations concerning the abandonment and plugging of deep wells.
Many states have regulations concerning abandonment of water wells and other
shallow holes, such as shot holes for seismic exploration. In most states,
abandonment procedures for wastewater injection wells, if regulated, are reg-
ulated by oil and gas agencies which permit and control abandonment of all
deep wells.
In a few states, injection wells are specifically covered by laws, reg-
ulations, or rules, in which abandonment requirements are included. Walker
and Cox (1976) provide a summary of the abandonment requirements for injection
wells in Michigan, Nebraska, Ohio, Oklahoma, and Texas. According to Walker
and Cox (1976), the following requirements, in effect in Oklahoma, appear to
be the most comprehensive:
The owner and/or operator of any industrial dis-
posal well shall be jointly and individually liable
and responsible for the proper plugging of said
wel 1 .
The owner and/or operator of any disposal well not
in operation for a period of six (6) months must
either apply for a new permit as specified in I tern
10.6 above or immediately plug the well.
Any well to be permanently abandoned shall be
i turned i a to 1 y p 1 ugged.
The owner and/or operator of a disposal well shall
notify Oklahoma Water Resources Board of his inten-
t i o n t o p 1 u 9. W r i 11. e n n o t i f i c a t i o n s h a 11 b e r p c e i v e d
at least ten (10) days prior to the coMiuencenont of
1)1 uqrji nc opera t. ions .
-------
The staff of Oklahoma Water Resources Board shall
be given the opportunity to be present at plugging
operations. The plugging operator shall notify the
Oklahoma Water Resources Board of the exact time
during which all plugging operations will take
place.
Every well shall be plugged in such a manner as
to permanently prevent the migration of any dis-
posed substances out of the disposal zone, as well
as the migration of oil, gas, or salt water into
or out of any productive formations, by means of
the well bore. Plugging shall also seal off all
fresh ground water strata encountered in the well
so as to prevent the entrance of salt water or the
escape of fresh ground water by means of the well
bore.
Before any casing is removed from a well, all
liquids shall be removed or displaced and the well
filled with mud. As the casing is removed, the
well shall be kept filled with mud.
Any uncased hole below the shoe of any casing to
be left in the well shall be filled with cement
to a depth of at least fifty (50) feet above the
shoe of the casing. If the well is completed with
a screen or liner and the screen or liner is not
removed, the well bore shall be filled with cement
at least fifty (50) feet above the screen or liner.
Whenever production casing is severed and removed,
the well bore shall be cemented from a point fifty
(50) feet below to a point fifty (50) feet above
the point of severance; provided that, if after such
cement plug has been set, the same string of casing
is again severed in the process of removal, further
cementing thereof shall not be required.
All fresh water zones encountered in the well shall
be sealed off and protected by adequate casing ex-
tending from a point at least fifty (50) feet below
the base of the lowest freshwater zone to within
three (3) feet of the top of the well bore, and by
completely filling the annular space behind such
casing with cement. If the surface or other casing
in the well meets these requirements, a cement plug
may be set at least fifty (50) feet below the shoe
of the casing. If the casing and cement behind the
casing do not meet the requirements of this sub-
section, the well bore shall be filled with cement
322
-------
from a point fifty (50) feet below the base of the low
est fresh-water zone to a point fifty (50) feet above
the shoe of the surface casing. The well bore shall,
in all events, be filled with cement from a point
three (3) feet below ground surface to a point thirty-
three (33) feet below ground surface.
All intervals between cement plugs in the well bore
shall be filled with mud.
Any "rat" or "mouse hole" used in the drilling of a
well with rotary tools shall be filled with mud to
a point eight (8) feet below ground level and with
cement from such point to a point three (3) feet
below ground level, and filled in with earth above
the top of the cement.
The top of the plug of any plugged well shall show
clearly, by permanent markings, whether inscribed
in the cement, or on a steel plate embedded in the
cement, the well number and date of plugging.
with in fifteen (15) days after a well h*s been
plugged, the owner or operator shall file a plug-
ging record, in duplicate, with the Oklahoma Water
Resources Board. If there is not a complete and
correct log of the well on file with the Board,
then the owner at the time of plugging shall fur-
nish and file a complete and correct log thereof,
or the best information available. The well bond
will be released only when the requirements of
this rule have been met.
Although the requirements of other states differ in detail, the Okla-
homa rules can be regarded as generally similar to rules or regulations found
elsewhere. Detailed suggestions for the abandonment of water wells and test
holes are given in the recently published "Manual of Water Well Construction
Practices" (U. S. Environmental Protection Agency, 1975), which was prepared
by the National Water Well Association.
Plugging procedures in well abandonment, di ffer greatly. Historically,
plugging has evolved from the driving of a "seasoned wooden plug" into
the well bore at the surface to requirements for the emplacement of cement
plugs and mud as described in the Oklahoma rules. In addition, existing
state abandonment, regulations often allow removal of casinc) fro P. a well be-
fore pluoqinq but. require the cutt. i rig-off of any remainim oisinq below the
orourul. In contrast with these provisions, which wore (U've! opod for the oil
.try, il is frequently stated in the literature 'ha' was town t or injection
plugged from the bottom to the surfdce with cement (Van Fver-
:.e, 1971; Rudd, 197?; '"Vrio River Valley W.itor Sanitation Corn-
Whip thor cdsim; should bo removed or no: depends on the
otis t r ,,i' : i or . !f ..ili ';i«.i'K; is (oriented * »"',.'• Bottom to top,
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as is usually the case today, then no casing will be removed prior to plugging.
Surface casing should a 1 ways be completely cemented when it is installed, and
it should never be removed. If intermediate and injection strings of casing
are not completely cemented during installation, then it is recommended that
they be pulled, perforated, slotted, or ripped, so that cement can be emplaced
in the annular space between the casing and the borehole wall, particularly
adjacent to permeable intervals. The purpose of cutting off casing below the
ground is to avoid interference with agriculture and other land use. Because
it may be important to accurately locate an abandoned wastewater injection
well at some time in the future, the Ohio River Valley Water Sanitation Com-
mission (1973) recommends that a permanent surface monument be established.
As far as is known, this recommendation has not been implemented by any state,
but it is believed to be worthy of consideration.
Wells that are abandoned during construction will vary so much in their
character that an individual abandonment procedure will need to be developed
for each well. Therefore, no general recommendations for the abandonment of
such wells are suggested.
The regulatory procedure for abandonment should include:
1. Approval of abandonment plan by the regulatory
agency.
2. Witnessing of plugging by a representative of
the regulatory agency.
3. Filing of abandonment and plugging report by
the wel1 operator.
The Ohio River Valley Water Sanitation Commission (1973) provides sample
forms of an application for an injection well abandonment permit (Figure 10-1)
and of a plugging and abandonment report (Figure 10-2).
324
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I. Well operator:
1. Name
2. Address
3. City
4. Waste injection well permit number
II. Detailed description of proposed plugging procedure (attach additional
sheets if necessary)
III. Planned date and time of plugging:
IV. Present well status:
1. Total volume of waste injected
2. Present injection rate
3. Present injection pressure (well-head)
4. Present well shut-in pressure
V. Plugging operations will be conducted by:
1. Name of Company
2. Address
3. City State
Signature of Authorized Representative of Operator Date
I. Application for a permit to plug and abandon shall be filed at least
30 days in advance of planned date of operation.
2. The planned date and time of pluqqim] should be specific and the
operation must be witnessed by a representative of the-
(State
rcqul a t.ury itqc>m. y)
[';r,i.!RF. 10-1. APPLICATION FOR PERMIT TO PI DH AMI ABANDON A Will (ORSANCO- ', ^'/'.]}
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I. WELL OPERATOR:
Name
Address
Waste injection well permit number
II. DESCRIPTION OF PLUGGING: (add additional sheets if necessary)
Depth
Plug materials -- type and volume From - To (feet)
III. FINAL STATUS
Total volume of waste injected as of
(date)
Final well shut-in pressure
Estimated horizontal extent of injected waste
IV. ASSOCIATED WORK
Pits and excavations filled ( ) yes
Equipment and debris removed ( ) yes
Permanent monument emplaced ( ) yes
Executed this __________ day of , 19 _
State of County of
(Signature of affiant)
(Typewritten name and title)
(Continued)
FIGURE 10-2. PLUGGING INFORMATION AND ABANDONMENT AFFIDAVIT (ORSANCO-1973]
326
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Figure 10-2. Continued
On this day of , 19 , before me appeared
, known to me to be the person whose
name is subscribed to the above instrument, who being by me duly sworn
in oath, states that he is authorized to make the above report and that
he has knowledge of the facts stated therein, and that said report is
true and correct.
SEAL
My commission expires
[Notary Public)
Plugging witnessed by
Authorized state representative
-------
REFERENCES
CHAPTER 10
Ohio River Valley Water Sanitation Commission. Underground Injection of Haste-
Haters in the Ohio Valley Region. ORSANCO, Cincinnati, Ohio. 1973.
Rudd, Heilson. Subsurface Liquid Waste Disposal and its Feasibility in Pennsyl-
vania . Pennsylvania Bureau of Topographic and Geologic Survey. Environ-
mental Geology Report 3. 1972. 103 pp.
U. S. Environmental Protection Agency. Manual of Water Well Construction Prac-
tices. EPA-570/9-75-001. U. S. Gov't. Printing Office, Washington, D. C.
1976. 156 pp.
Van Everdingen, R. 0., and Freese, R. A. Subsurface Disposal of Waste in Can-
ada. Inland Waters Branch, Department of the Environment Technical Bul-
letin No. 49. 1971. 64 pp.
Walker, W. R., and Cox, W. E. Deep Well Injection of Industrial Wastes:
Government Controls and Legal Constraints. Virginia Water Resources
Research Center, Blacksburg, Virginia. 1976. 163 pp.
328
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GLOSSARY
abandoned well: A well whose use has been permanently discontinued or which
is in a state of disrepair such that it cannot be used for its intended pur-
pose or for observation purposes.
acidizing: The injection of acid through the borehole or well into a carbonate
or sandstone formation to effect an increase of permeability and porosity
by dissolving the acid soluble portion of the rock constituents. Fre-
quently used with hydraulic fracturing methods.
aeration: The mechanism by which air and liquid are brought into close con-
tact. This can be accomplished by one or more of the following methods:
(a) spraying the liquid in the air (b) bubbling air through the liquid
(c) agitating the liquid to promote surface absorption of air.
dquiclude: A body of relatively impermeable rock that is capable of absorbing
water slowly, but functions as an upppr nr lowpr boundary of an aquifer
and does not transmit ground water rapidly enough to supply a well or
spring.
aquifer: A porous, permeable, water-bearing geologic body of rock. Generally
restricted to materials capable of yielding an appreciable amount of water.
aquitard: A confining bed that retards but does not prevent the flow of wa-
ter to or from an adjacent aquifer; a leaky confining bed. It does not
readily yield water to wells or springs, but may serve as a storage unit
for ground water.
arkose: A feldspar-rich, typically coarse-grained sandstone, commonly pink
or reddish to pale gray or buff, composed of angular to subangular grains
that may be either poorly or moderately well sorted, usually derived
from the rapid disintegration of granite or granitic rocks (including
high-grade feldspathic gneisses and schists), and often closely resembl-
ing or having the appearance of a granite.
artesian: An adjective referring to ground water confined under sufficient
hydros t.a t. i c pressure to rise above the upper surface of the aquifer.
trt.esian ti (infer: Confined aquifei
(•>rr,.)Mo, of ten, but not. ';e>. oss^oi i y I'vis i n -shaped , inc.1 Hiding
'.jiior whose potenti one' ri (. srjrf,u:o typically is above the
'i f.ne t op1: uirdphi c:a 11 y IOVJI-T- pnr'inr, of the tcrrane. C xdi1'.-
s'l.v : ro1'1 ,ireos a few Msrn'jre.1 foot ,it TOSS tn several hun-
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baffles: Deflector vanes, guides, grids, gratings, or similar devices con-
structed or placed in flowing water or wastewater systems to check or
affect a more uniform distribution of velocities; adsorb energy; divert,
guide, or agitate the liquids; and check eddies.
biological wastewater treatment: Forms of wastewater treatment in which bac-
terial or biochemical action is intensified to stabilize, oxidize, and
nitrify the unstable organic matter present. Intermittent sand filters,
contact beds, trickling filters, and activated sludge processes are exam-
ples.
BOD: The abbreviation for biochemical oxygen demand. The quantity of oxygen
used in the biochemical oxidation or organic matter in a specified time,
at a specified temperature, and under specified conditions. Also, a
standard test used in assessing required wastewater treatment.
brine: Concentrated salt solution remaining after removal of distilled prod-
uct; also, concentrated brackish saline or sea waters containing more
than 100,000 mg/1 of total dissolved solids.
capillary conductivity: The ability of an unsaturated soil or rock to trans-
mit water or another liquid. As the larger interstices are partly occu-
pied by air or other gas, rather than a liquid, the liquid must move
through and in bodies surrounding point contacts of rock or soil parti-
cles. For water, the conductivity increases with the moisture content,
from zero in a perfectly dry material to a maximum equal to the hydrau-
lic conductivity, or effective permeability at 100% water saturation.
capillary head: The capillary potential expressed as head of water.
capillary potential: A number representing the work required to move a unit
of mass of water from soil or rock to an arbitrary reference location
and energy state (SSSA, 1965, p. 348). Symbol: M.Cf: capillary head.
cement: Chemically precipitated mineral material that occurs in the spaces
among the individual grains of a consolidated sedimentary rock, thereby
binding the grains together as a rigid coherent mass; it may be derived
from the sediment or its entrapped waters, or it may be brought in by
solution from outside sources. The most common cements are silica
(quartz, opal, chalcedony), carbonates (calcite, dolomite, siderite),
and various iron oxides; others include barite, gypsum, anhydrite, and
pyrite. Clay minerals and other fine clastic particles should not be
considered as cements.
cementation: The diagenetic process by which coarse clastic sediments become
lithified or consolidated into hard, compact rocks through the deposition
or precipitation of minerals in the spaces among the individual grains
of the sediment. It may occur simultaneously with sedimentation, or the
cement may be introduced at a later time. Cementation may occur by sec-
ondary enlargement. Syn: agglutination.
330
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cementing: The operation whereby a cement slurry is pumped into a drill
hole and/or forced behind the casing for such purposes as: sealing the
casing to the walls of the hole; preventing unwanted leakage of fluids
into the hole or migration of liquids or gas into or out of the hole;
closing the hole back to a shallower depth; sealing a dry hole; or re-
drilling to straighten the hole; and plugging and abandonment.
centipoise: A unit of viscosity based on the standard of water at 20° C.,
which has a viscosity of 1.005 centipoises.
CGS system: A metric system of physical measurements in which the fundamental
units of length, mass, and time are the centimeter, the gram, and the
mean solar second.
chelating agent: A chemical or complex which causes an ion, usually a metal,
to be joined in the same molecule by both ordinary and coordinate va-
lence forces. Such linkages result in the formation of one or more
heterocyclic rings in which the metal atom is part of the ring. Com-
mercially available chelating agents may be used to remove traces of
metal ions in industrial and biological processes.
chemical oxygen demand (COD): A measure of the oxygen-consuming capacity of
inorganic and organic matter present in water or wastewater. It is
expressed as the amount of oxygen consumed from a chemical uAiuant in a
specific test. It does not differentiate between stable and unstable
organic matter and thus does not necessarily correlate with biochemical
oxygen demand.
chemical precipitation: Precipitation induced by addition of chemicals.
chemical treatment: Any process involving the addition of chemicals to
obtain a desired result.
clay minerals: One of a complex and loosely defined group of finely crystal-
line, meta colloidal, or amorphous hydrous silicates essentially of
aluminum with a monoclinic crystal lattice of the two or three layer
type in which silicon and aluminum ions have tetrahedral coordination
in respect to oxygen. Clay minerals are formed chiefly by chemical
alteration or weathering of primary silicate minerals such as feldspars,
pyroxenes, and amphiboles and are found in clay deposits, soils, shales,
and mixed with sand grains in many sandstones. They are characterized
by small particle size and ability to adsorb substantial amounts of
water and ions on the surfaces of the particles. The most common clay
minerals belong to the kaolin, inontmorri1ionite, and i 11ite qroups.
coiigul a t, ion: The destabi 1 i zation and initial aggregation of colloidal arid
finely divided suspended nattor by the addition of a 11 ex "forming chemi-
cal of by biological processes.
comprev, it> i 1 i ty: The rcc r i poca I of bulk modules (if el ast u i t,y . It.4, symbol
m.oriul us of compress i on .
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concentration: (1) The amount of a given substance dissolved in a unit volume
of solution. (2) The process of increasing the dissolved solids per
unit volume of solution, usually by evaporation of the liquid.
concentration tank: A settling tank of relatively short detention period in
which sludge is concentrated by sedimentation or floatation before
treatment, dewatering, or disposal.
conductivity bridge: A device which provides a means of measuring conductivity,
whereby a conductivity cell forms one arm of a Wheats tone Bridge, a stan-
dard fixed resistance forms another arm, and a calibrated slide wire
resistance with end coils provides the remaining two arms. A high-fre-
quency alternating current is supplied to the bridge.
confined aquifer: An aquifer bounded above and below by impermeable beds or
beds of distinctly lower permeability than that of the aquifer itself;
an aquifer containing confined ground water.
confined ground water: A body of ground water overlain by material sufficiently
impervious to sever free hydraulic connection with overlying ground water
except at the intake. Confined water moves in conduits under the pressure
due to difference in head between intake and discharge areas of the con-
fined water body.
confining bed: A body of impermeable or distinctly less permeable material
stratigraphically adjacent to one or more aquifers. Cf: aquitard;
aquifuge; aquiclude.
core barrel: (a) A hollow tube or cylinder above the bit of a core drill,
used to receive and preserve a continuous section or core of the mater-
ial penetrated during drilling. The core is recovered from the core
barrel, (b) The tubular section of a corer, in which ocean-bottom sedi-
ments are collected either directly in the tube or in a plastic liner
placed inside the tube.
core bit: A hollow, cylindrical drill bit for carving, removing, and holding
a core or sample of rock or soil material from the drill hole; the cut-
ting end of a core drill. Syn: coring bit.
core drill: (a) A drill (usually a rotary drill, rarely a cable-tool drill)
that cuts, removes, and brings to the surface a cylindrical rock sample
(core) from the drill hole. It is equipped with a core bit and a core
barrel, (b) A lightweight, usually mobile drill that uses drill tubing
instead of drill pipe and that can (but need not) core down from grass
roots.
core drilling: Drilling with a core drill; the act or process of obtaining a
core by drilling. Syn: coring.
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corrosion: The gradual deterioration or destruction of a substance or material
by chemical action, frequently induced by electrochemical processes.
The action proceeds inward from the surface.
cuttings: Rock chips or fragments produced by drilling and brought to the
surface. The term does not include the core recovered from core drill-
ing. Also: well cuttings; sludge; drillings. Syn: drill cuttings.
darcy: A standard unit of permeability, equivalent to the passage of one cu-
bic centimeter of fluid of one centipoise viscosity flowing in one sec-
ond under a pressure differential of one atmosphere through a porous
medium having an area of cross-section of one square centimeter and a
length of one centimeter. A millidarcy is one one-thousandth of a darcy.
Darcy's law: A derived formula for the flow of fluids on the assumption that
the flow is laminar and that inertia can be neglected. The numerical
formulation of this law is used generally in studies of gas, oil, and
water production from underground formations.
degasification: The removal of a gas from a liquid medium. In water treat-
ment, the removal of oxygen from water to lessen its corrosion potential.
This may be accomplished by mechanical methods, chemical methods, or a
combination of both.
diatomaceous earth: A fine, siliceous earth consisting mainly of the skeletal
remains of diatoms (unicellular animals).
diatomaceous earth filter: A filter used in water treatment, in which a built-
up layer of diatomaceous earth serves as the filtering medium.
dissolved oxygen: The oxygen dissolved in water, wastewater, or other liquid,
usually expressed in milligrams per liter, parts per million, or percent
of saturation. Abbreviated DO.
dissolved solids: The anhydrous residues of the dissolved constituents in
water, or the sum of the dissolved constituents.
distillation: A process of evaporation and re-condensation used for separat-
ing liquids into various fractions according to their boiling points or
boiling ranges.
drilling fluid: A heavy suspension, usually in water but sometimes in oil,
used in rotary drilling, consisting of various substances in a finely
divided state (conmonly bentonitic clays and chemical additives sue'1 as
barite), introduced continuously down the drill pipe under hydrostatic
pressure, out through openings in the drill hit, and hack up in the an-
nular spate between the pipe and the borehole1 walls and to a vjrfacf
pit where- cut'in'is art1 removed. The fhrid is then rointroduord irti.
the nine. It is used to lubricate.' and cocl t m1 hit, to carry ' lie i ut-
tinqs up fror; the hot torn, and to prevent si ou^hinc; and cave-iir. by
plasterim; and conso lida t in;j the walls with ,1 <:!ay linincj, therelj,' rsif.-
i 'V."; casinc jrnici essa<', dijrim:; drilling, and ,! r.rj M (\p ( t inn ;'rr\'.i;ri'1,
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drill-stem test: A procedure for determining productivity of an oil or gas
well by measuring reservoir pressures and flow capacities while the
drill pipe is in the hole and the well is full of drilling mud. A drill
stem test may be done in a cased or uncased hole.
effective porosity: The measure of the total volume of interconnected void
space of a rock, soil or other substance. Effective porosity is usually
expressed as a percentage of the bulk volume of material occupied by the
interconnected void space.
effective stress: The average normal force per unit area transmitted directly
from particle to particle of a soil or rock mass. It is the stress that
is effective in mobilizing internal friction. In a saturated soil, in
equilibrium, the effective stress is the difference between the total
stress and the neutral stress of the water in the voids; it attains a
maximum value at complete consolidation of the soil.
emulsion: A heterogeneous mixture of two or more liquids not normally dis-
solved in one another, but held in suspension one in the other by force-
ful agitation or by emulsifiers which modify the surface tension of the
droplets to prevent coalescence.
emulsifying agent: A compound which enhances the strength of the interfacial
film around the droplets of the dispersed liquid by providing layers of
electrical charges, thus increasing the stability of emulsions. Stabil-
ity is created because finely divided droplets are prevented from coal-
escing into large droplets.
facies: A term used to refer to a distinguished part or parts of a single
geologic entity, differing from other parts in some general aspect;
e. g., any two or more significantly different parts of a recognized body
of rock or stratigraphic composition. The term implies physical close-
ness and genetic relation or connection between the parts.
facies change: A lateral or vertical variation in the lithologic or paleon-
tologic characteristics of contemporaneous sedimentary deposits. It is
caused by, or reflects, a change in the depositional environment.
Cf: facies evolution.
facies contour: The trace (on a map) of a vertical surface that cuts a three-
dimensional rock body into facies segments; a line indicating equivalence
in lithofacies development.
facies map: A broad term for a stratigraphic map showing the gross area!
variation or distribution (in total or relative content) of observable
attributes or aspects of different rock types occurring within a desig-
nated stratigraphic unit, without regard to the position or thickness
of individual beds in the vertical succession; specif, a lithofacies
map. Conventional facies maps are prepared by drawing lines of equal
magnitude through a field of numbers representing the observed values
of the measured rock attributes. Cf: vertical-variability map.
334
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fault: A surface or zone of rock fracture along which there has been dis-
placement, from a few centimeters to a few kilometers.
filtrate: The liquid which has passed through a filter.
filtration: The process of passing a liquid through a filtering medium (which
may consist of granular material, such as sand, magnetite, or diatoma-
ceous earth, finely woven cloth, unglazed porcelain, or specially pre-
pared paper), for the removal of suspended or colloidal matter.
fishing tools: The specialized equipment used for searching for and attempt-
ing to recover a piece or pieces of drilling eauioment (such as sections
of pipe, cables, or casing) that has become detached, broken or lost from
a drilling tool and left or that has been accidentally dropped into the
borehole.
floe: Small masses, commonly gelatinous, formed in a liquid by the reaction
of a coagulant, through biochemical processes, or by agglomeration.
flocculation: The agglomeration of colloidal and finely divided suspended
matter after coagulation by gentle stirring either by mechanical or
hydraulic means.
flotation: The raising of suspended matter to the surface of the liquid in
a tank as scum - by aeration, the evolution of gas, chemicals, electrol-
ysis, heat, or bacterial decomposition - and the subsequent removal of
the scum by skimming.
flow rate: The volume per time unit given to the flow of water or othe
quid substance which emerges from an orifice, pump, turbine or passes
along a conduit or channel, usually expressed as cubic feet per second
(cfs), gallons per minute (gpm) or million gallons per day (mgd).
fluid potential: With reference to ground water, the mechanical energy per
unit mass of a fluid (here, water) of any given point in space and time,
with respect to an arbitrary state and datum. At a given point in a
body of liquid, the fluid potential is proportional to the head; it is
the head multiplied by the acceleration due to gravity.
formation: A body of rock characterized by a degree of lithologic homogeneity;
it is prevailingly, but not necessarily, tabular and is mappable on the
earth's surface or traceable in the subsurface.
formation water: Water present, in a water-bearing formation tinder natural
conditions as opposed to introduced fluids, such as drilling mud.
sical loqs: The records of a variety of loqqinq tools which measure the
oeopnys i ca 1 properties of qeolnqic formations penetrated and their con-
tained fluids. These properties include electrical conductivity and re-
si', tivit.v, the ability to transmit and reflect sonic enecqy, natural
rad i,),i( f i yi t.v1, hydroqpn ion content, tenperature, qravi t *', etc. These
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geophysical properties are then interpreted in terms of lithology,
porosity, fluid content and chemistry.
geothermal gradient: The rate of increase of temperature in the earth with
depth. The gradient near the surface of the earth varies from place
to place depending upon the heat flow in the region and on the thermal
conductivity of the rocks. The approximate geothermal gradient in the
earth's crust is about 25°C/km.
gravity prospecting: The determination of specific gravity differences of
rock masses by mapping the force of gravity of an area, using a gravi-
meter. Syn: gravitational method.
gravity separation: A separation process by which an oil and water mixture
is allowed to separate into two phases, with the lighter oil phase ris-
ing to the surface of the heavier water phase.
group: General: An association of any kind based upon some feature of simi-
larity or relationship. Stratig: Lithostratigraphic unit consisting
of two or more formations; more or less informally recognized succession
of strata too thick or inclusive to be considered a formation; subdiv-
isions of a series.
grout: A cementitious component of high water content, fluid enough to be
poured or injected into spaces such as fissures surrounding a well bore
and thereby filling or sealing them. Specifically a pumpable slurry of
Portland cement, sand, and water forced under pressure into a borehole
during well drilling to seal crevices and prevent the mixing of ground
water from different aquifers.
hardness (water): A property of water causing formation of an insoluble resi-
due when used with soap and causing formation of a scale in vessels in
which water has been allowed to evaporate. It is primarily due to the
presence of calcium and magnesium ions but also to ions of other alkali
metals. Incrustation caused by the precipitation of carbonate minerals
in hard water frequently will cause well screens and areas of the rock
formation around the well to clog, resulting in a reduction of fluid
flow into or out of the well. Hardness of water is generally expressed
as parts per million CaCC^, also milligrams per liter.
hydraulic conductivity: Ratio of flow velocity to driving force for viscous
flow under saturated conditions of a specified liquid in a porous medium.
hydraulic head: (a) The height of the free surface of a body of water above
a given subsurface point (b) The water level at a point upstream from
a given subsurface point downstream (c) The elevation of the hydraulic
grade line at a given point above a given point of a pressure pipe.
image-well theory: The effect of a barrier boundary on the drawdown in a well,
as a result of pumping from another well, is the same as though the aqui-
fer were infinite and a like discharging well were located across the
real boundary on a perpendicular thereto and at the same distance from
the boundary as the real pumping well.
336
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injection schedule: A timetable for the disposal of liquid waste in an injec-
tion well. This timetable is based on the characteristics of the waste
liquid, i. e., viscosity, temperature, chemistry, reactivity, etc.;
the injection rate; and the physical characteristics of the receiving
formation.
injection well: (a) A recharge well, (b) A well into which water or a gas
is pumped for the purpose of increasing the yield of other wells in the
area, (c) A wel'i used to dispose of fluids in the subsurface environ-
ment by allowing it to enter by gravity flow, or injection under pres-
sure.
interstice: An opening or space in a rock or soil that is not occupied by
sol id matter.
interstitial water: Water contained in the interstices of rocks. It may or
may not be connate water. The origin of the water is not specified.
ion exchange: A chemical process involving reversible interchange of ions
between a liquid and a solid or a liquid and a liquid, but no radical
change in structure of the solid.
isopach: A line drawn on a map through poinlb uT equal thickness of a desig-
nated stratigraphic unit or group of stratigraphic units.
isopach map: A map that shows the thickness of a bed, formation or other
tabular body throughout a geographic area; a map that shows the varying
true thickness of a designated stratigraphic unit or group of strati-
graphic units by means of isopachs plotted normal to the bedding or
other bounding surface at regular intervals.
jetting: (a) A method of well construction where the casing is sunk by driv-
ing while the material inside is washed out by a water jet and carried
to the top of the casing (b) A method of inserting well points by means
of a water jet.
iiner casing: Any string of casing whose top is situated at any point below
the surface.
lithology: (a) The description of rocks on the basis of such characteristics
as color, structures, mineralogic composition, and grain size, (b)
The physical character of a rock.
ma(jnetic survey: Measurement of a component, or element of the geomagnetic
field at different locations. It, is usually made to map either the
broad patterns of the Earth's main field or local anomalies due to
variation in rook I:M quo t i nation, also: ,ieronan,net ic survey.
;•:!.'(. han i ca 1 agitation: The nixing of liquids, inrliHinq introduction ot ;itnos-
pheric. oxyqen into a liquid by trie met. han i < a 1 ..irtinn of a paddle, p,:>r,i v , or ' 'jrb i re TOC. Kin i svv,.
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member: A division of a formation, generally of distinct lithologic character
or of only local extent. A specially developed part of a varied forma-
tion is called a member, if it has considerable geographic extent. Mem-
bers are commonly, though not necessarily, named.
millidarcy: The customary unit of fluid permeability, equivalent to 0.001
darcy. Abbrev: md.
mud logs: The record of continuous analysis of a drilling mud or fluid for
oil and gas content.
neutralization: Reaction of acid or alkali with the opposite reagent until
the concentrations of hydrogen and hydroxyl ions in the solution are
approximately equal.
oil-field brine: Connate waters encountered during drilling rocks at depth.
These waters usually have a high concentration of calcium and sodium
salts and a dominance of chloride ion.
organic chemicals: Chemical substances of animal or vegetable origin, or more
correctly, of basically carbon structure, comprising compounds consisting
of hydrocarbons and their derivatives.
oxidation: The addition of oxygen to a compound. More generally, any reaction
which involves the loss of electrons from an atom.
pH: The negative logarithm of the hydrogen-ion concentration. The concentra-
tion is the weight of hydrogen ions, in grams, per liter or solution.
Neutral water, for example, has a pH value of 7 and a hydrogen ion
concentration of 10.
packer: In well drilling, a device lowered in the lining tubes which swells
automatically or can be expanded by manipulation from the surface at
the correct time to produce a water-tight joint against the sides of
the borehole or the casing, thus entirely excluding water from different
horizons.
percentage map: A facies map that depicts the relative amount (thickness) of
a single rock type in a given stratigraphic unit.
permeability: The property of capacity of a porous rock, sediment, or soil
for transmitting a fluid without impairment of the structure of the
medium; it is a measure of the relative ease of fluid flow under unequal
pressure. The customary unit of measurement is the millidarcy.
piezometric surface: See potentiometric surface.
plugging: The act or process of stopping the flow of water, oil, or gas in
strata penetrated by a borehole or well so that fluid from one stratum
will not escape into another or to the surface; especially the sealing
up a well that is tube abandoned. It is usually accomplished by in-
serting a plug into the hole, by sealing off cracks and openings in the
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sidewalls of the hole, or by cementing a block inside the casing. Cap-
ping the hole with a metal plate should never be considered as an ade-
quate method of plugging a well.
plugging records: A systematic listing of permanent or temporary abandonment
of water, oil, gas, test, exploration and waste injection wells. The
plugging record should contain a well log, description of amounts and
types of plugging material used, the method employed for plugging, a
description of formations which are sealed and a graphic log of the
well showing formation location, formation thickness, and location of
plugging structures.
polymerization: A chemical reaction in which two or more small molecules com-
bine to form larger molecules that contain repeating structural units of
the original molecules.
porosity: The property of a rock, soil, or other material of containing inter-
stices. It is commonly expressed as a percentage of the bulk volume of
material occupied by interstices, whether isolated or connected.
potentiometric surface: An imaginary surface representing the static head of
ground water and defined by the level to which water will rise in a
well. The water table is a particular potentiometric surface.
pre-injection treatment: The conditioning of a liquid waste to remove or
neutralize substances which may be damaging to the injection system
equipment or tend to plug the system.
pressure: (1) The total load or force acting on a surface. (2) In hydraulics,
without qualifications, usually the pressure per unit area or intensity
of pressure above local atmospheric pressure expressed, for example, in
pounds per square inch, kilograms per square centimeter.
pressure flotation: A process in which the wastewater is saturated with air
under pressure and then passed into a floation chamber at atmospheric
pressure. Under reduced pressure, the air is released from solution
as small bubbles that carry the oil globules to the surface, where they
are skimmed off.
primary cementing: Is the process of placing cement behind the casing to fill
the annular space between the casing and the open hole. It also func-
tions: (1) to bond the casing to the formation, (2) to protect injec-
tion zones - reduces caving, (3) to seal off fresh water or mineral
zones, (4) to isolate hiqh pressure zones, (5) and protects casing from
corrosive waters.
primary porosity: The porosity thai develops during the final staqes of sedi-
mentation or that, was present within sedimentary parti<: les at the time
of deposition. It includes all depir. j; inna 1 jujrosi'y ol t i>» sediments,
or 1. ho ro: k .
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ratio-type lithofacies map: A map showing area! relations of lithofacies
based on limiting values of two ratios, commonly clastic and sand-shale
ratios.
rapid sand filters: There are two types: (1) Gravity rapid sand are composed
of a bed several feet thick that is generally deposited as several lay-
ers of varying grain sizes, with fine sand at the top and gravel at the
base. Anthracite of varying particle size is also used as a filter med-
ium. A typical rate of flow is 2 gpm per ft^. (2) Pressure sand filter-
pressure sand filters are based on the same principles as the gravity-
feed rapid sand filter, except that the filter media and underdrain
system are placed in a cylindrical tank, and the water is passed through
the filter under pressure.
reduction: The opposite of oxidation. The chemical action which works to de-
crease the positive valence of an ion.
reverse rotary drilling: A method of drilling wells where waste material is
carried away by water or mud forced up the inside of the drill pipe
rather than the outside of the pipe as in the normal rotary drilling
technique. Greater upward velocities in the small interior area add a
greater waste carrying capacity.
rotary drilling: A common method of drilling, being a hydraulic process con-
sisting of a rotating drill pipe at the bottom of which is attached to
a hard-toothed drill bit. The rotary motion is transmitted through the
pipe from a rotary table at the surface: as the pipe turns, the bit
loosens or grinds a hole in the bottom material. During drilling, a
stream of drilling mud is in constant circulation down the pipe and
out through the bit from where it and the cuttings from the bit are
forced back up the hole outside the pipe and into pits where the cut-
tings are removed and the mud is picked up by pumps and forced back down
the pipe.
secondary cementing: Is used for maintenance repair operations, and is under-
taken to plug damaged casing, caving injection zones and to abandon in-
efficient injection wells.
secondary porosity: The porosity developed in a rock formation subsequent to
its deposition or emplacement, either through natural processes of
dissolution, stress distortion, or artificially through acidization
or the mechanical injection of coarse sand.
sedimentation: The process of removal of solids from water by gravity set-
tling.
seismic survey: The gathering of seismic data from an area; the initial phase
of seismic prospecting.
sequestering agent: A chemical that causes the coordination complex of cer-
tain phosphates with metallic ions in solution so that they may no longer
be precipitated. Hexametaphosphates are an example: calcium soap pre-
340
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cipitates are not produced from hard water treated with them. Also, any
agent that prevents an ion from exhibiting its usual properties because
of close combination with an added material.
settling reservoir: A reservoir consisting of a series of shallow basins ar-
ranged in steps and connected by long conduits allowing the removal of
only the clear upper layer of water in each basin.
sludge: (1) Mud obtained from a drill hole in boring; mud from drill cuttings.
The term has also been used for the cuttings produced by drilling. (2)
A semi-fluid, slushy, and murky mass or sediment of solid matter result-
ing from treatment of water, sewage, or industrial and mining wastes,
and often appearing as local bottom deposits in polluted bodies of water.
slow sand filter: A filter composed of beds of granular particles classified
as slow which implies a very low flow velocity (<0.2 gpm/ft^). This
filter is not generally useful for pre-injection treatment.
slurry: A very wet, highly mobile, semiviscous mixture or suspension of finely
divided, insoluble matter.
solubility: The equilibrium concentration of a solute in a solution saturated
with respect to that solute at a given temperature and pressure.
solution: A process of chemical weathering by which rock material passes into
calcium carbonate in limestone or chalk by carbonic acid derived from
rainwater containing carbon dioxide acquired during its passage through
the atmosphere.
solution cavity: (a) An opening produced by direct solution by water penetra-
ting pre-existing interstices, (b) An opening resulting from the decom-
position of less soluble rocks by water penetrating pre-existing inter-
stices, followed by solution and removal of the decomposition products.
(c) solution channel.
specific capacity: The rate of discharge of a water well per unit of draw-
down, commonly expressed in gallons per minute per foot. It varies slow-
ly with duration of discharge. If the specific capacity is constant
except for the time variation, it is proportional to the transmissivity
of the aquifer.
specific conductance: The electrical conductivity of a water sample at
?5" C. (77 F) , expressed in micro-ohms per centimeter.
specific gravity: The ratio of the mass of a body to the mass of an equal
vol nine of wa tor.
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specific yield: The ratio of the volume of water a given mass of saturated
rock or soil will yield by gravity to the volume of that mass. This
ratio is stated as a percentage. Cf: effective porosity; storage co-
efficient.
storage coefficient: In an aquifer, the volume of water released from storage
in a vertical column of 1.0 square feet when the water table or other
potentiometric surface declines 1.0 foot. In an unconfined aquifer, it
is approximately equal to the specific yield.
structure-contour map: A map that portrays subsurface configuration by means
of structure contour lines; contour map; tectonic map. Syn: structural
map; structure map.
sulfate-reducing bacteria: Anaerobic bacteria capable of assimilating oxygen
from sulfate compounds, thereby reducing them to sulfides.
surface casing: The first string of well casing to be installed in the well.
The length will vary according to the surface conditions and the type
of well.
surfactant: An abbreviation for surface-active agent. The active agent in
detergents that possesses a high cleaning ability. These agents in sol-
ution exhibit special characteristics that include concentrations of in-
terfaces, formation of micelles, solubilization, the lowering of surface
tension, and the increased penetration of the liquid in which they are
dissolved.
surge: A momentary increase in flow in an open conduit or pressure in a closed
conduit that passes longitudinally along the conduit, usually due to sud-
den changes in velocity.
suspended sclids: (1) Solids that either float on the surface of, or are in
suspension in, water, wastewater, or other liquids, and which are large-
ly removable by laboratory filtering. (2) The quantitv of material re-
moved from wastewater in a laboratory test, as prescribed in "Standard
Methods for the Examination of Water and Wastewater" and referred to as
nonfilterable residue.
swab: A piston-like device equipped with an upward-opening check valve and
provided with flexible rubber suction caps, lowered into a borehole or
casing by means of a wire line for the purpose of cleaning out drilling
mud or of lifting oil.
tectonic: Said of or pertaining to the forces involved in, or the resulting
structures or features of, tectonics. Syn: geotectonic.
test hole: A general term for any type of hole, pit, shaft, etc., dug or
drilled for subsurface reconnaissance.
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thinner: Is applied to a substance that reduces the apparent vicsocity and
gel development of mud without lowering the density. The effectiveness
of a thinner depends upon the condition of the mud, the pH, and the
amount of the contaminants present.
tie-back liner: A liner which extends from the top of a liner all the way
back to the surface. They are fully cemented to protect other casing
strings against pressure and/or corrosion.
total porosity: The measure of all void space of a rock, soil or other sub-
stance. Total porosity is usually expressed as a percentage of the bulk
volume of material occupied by the void space.
toxin: A colloidal, proteinaceous, poisonous substance that is a specific
product of the metabolic activities of a living organism and is usually
very unstable, notably toxic when introduced into the tissues and typi-
cally capable of inducing antibody formation.
transmissivity: In an aquifer, the rate of which water of the prevailing kine-
matic viscosity is transmitted through a unit width under a unit hydraulic
gradient. Though spoken of as a property of the aquifer, it embodies also
the saturated thickness and the properties of the contained liquid.
turbidity: The state, condition, cr quality of opaqueness or reduced clarity
of a fluid, due to the presence of suspended matter. A measure of the
ability of suspended material to disturb or diminish the penetration of
1ight through a fluid.
unconsolidated material: A sediment that is loosely arranged, or whose parti-
cles are not cemented together, occurring either at the surface or at
depth.
viscosity: The property of a substance to offer internal resistance to flow;
its internal friction. Specifically, the ratio of the rate of shear
stress to the rate of shear strain. This ratio is known as the coeffi-
cient of viscosity.
volatile chemicals: Chemicals capable of being evaporated at relatively low
temperatures.
wastewater: Spent water. According to the source, it may be a combination
of the liquid and water-carried wastes from residence, commercial build-
ings, industrial plants, and institutions, together with any ground wa-
ter, surface water, and storm water which may be present. In recent
years, the term wastewater has taken precedence over the term sewage.
water quality: The chemical, physical, and biological characteristics of
water with respect, to its suitability for a particular purpose.
well locj: A log obtained from a well, showing such information as resistivity,
radioactivity, spontaneous potential, and acoustic velocity as a func-
tion of depth; esp. a litholoqic record of the rocks pcnetrat*Ml.
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well plug: A water tight and gas tight seal installed in a borehole or well
to prevent movement of fluids. The plug can be a block cemented inside
the casing.
well record: A concise statement of the available data regarding a well,
such as a scout ticket; a full history or day-by-day account of a well,
from the day the well was surveyed to the day production ceased.
well stimulation: Term used to describe several processes used to clean the
well bore, enlarge channels, and increase pore space in the interval
to be injected thus making it possible for wastewater to move more
readily into the formation. The followinq are well stimulation tech-
niques: (1) surging,(2) jetting, (3) blasting, (4) acidizing, and (5)
hydraulic fracturing.
well monitoring: The measurement, by on-site instruments or laboratory methods,
of the water quality of a water well. Monitoring may be periodic or
continuous.
WOC: "Waiting on Cement" is the period beginning when the plug bumps the
float collars and ends when the cement plug is drilled out. It is re-
quired for the cement to attain required strength.
344
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO
EPA-600/2-77-240
TITLE AND SUBTITLE
AN INTRODUCTION TO THE TECHNOLOGY OF
SUBSURFACE WASTEWATER INJECTION
5. REPORT DATE
December 1977 issuing date
6. PERFORMING ORGANIZATION CODE
3. RECIPIENT'S ACCESSI Of* NO.
7. AUTHOR(S)
Don L. Warner, University of Missouri--Rolla
Jay H. Lehr,
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
National Water Well Association
500 West Wilson Bridge Road
Worthington, Ohio 43085
10. PROGRAM ELEMENT NO.
1CC614
11. CONTRACT/GRANT NO.
No. R-803889
12. SPONSORING AGENCY NAME AND ADDRESS
Robert S. Kerr Environmental Research Lab. - Ada, OK
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
13. TYPE OF RE PORT AND PERIOD COVERED
Final (July '75 - July '71
14. SPONSORING AGENCY CODE
EPA/600/15
EPA/600/14
15. SUPPLEMENTARY NOTES
This report was co-sponsored by the Municipal Environmental Research Laboratory,
Office of.Researchrapd Development, U.S. Environmental Protection Agency,
Cincinnati, Onio 45268 K
16. ABSTRACT
An introduction to the design, construction, operation, and abandonment
of subsurface wastewater injection systems is presented.
Local geologic and hydrologic characteristics of the injection and confining
intervals are considered along with the physical, chemical, and biological
compatibility of the receiving zone with the wastewater to be injected.
Design and construction aspects of injection wells are presented along
with recommended preinjection testing, operating procedures, and emergency
precautions. Monitoring requirements are discussed, in addition to records
maintenance and proper well abandonment procedures.
Injection Wei 1s
Waste Disposal
Design
Construction
:;.1F\' Tlf ih RS
t\'D(D I! H\'<,
Techno! ogy Dpvel opmenf,
Underground Di sposal
Moni torinq
•i ".( i;..i(' T v ci ,-.'.', ,•.,,., .i,v,-, ,,
Dru. 1 ass i4. i cci
13 B
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