PB90-227232
A FEASIBILITY STUDY OF THE EFFECTIVENESS OF DRILLING
MUD AS A PLUGGING AGENT IN ABANDONED WELLS
Oklahoma State University
Stillwater, OH
Jun 90
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
NT1S
-------
EPA/600/2-90/022
June 1990
A FEASIBILITY STUDY OF THE EFFECTIVENESS
OF DRIL'LING MUD AS A PLUGGING AGENT IN
ABANDONED WELLS
by
Marvin D. Smith
Randolf L. Perry
Gary F. Stewart
William A. Holloway
Fred R. Jones
Oklahoma State University
Stillwater, Oklahoma 74078
Cooperative Agreement CR-814238
Project Officer
Don C. Draper
Applications and Assistance Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing/
1. REPORT NO.
EPA/600/2-90/022
3. RECIP
'ECIPlENT'S ACCESSION NO >^ -^
PB90 227232IIS
A. TITLE AND SUBTITLE
A FEASIBILITY STUDY OF THE EFFECTIVENESS OF DRILLING MUD
AS A PLUGGING AGENT IN ABANDONED WELLS
5. REPORT OATE
June 1990
6. PERFORMING ORGANIZATION COO6
7. AUTHOR(S)
Marvin D. Smith, Randolf L. Perry, Gary F. Stewart,
William A. Holloway, Fred R. Jones
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Oklahoma State University
Still water. OK- 74078
10. PROGRAM ELEMENT NO.
CBPC1A
11 CONTRACT/GRANT NO.
CR-814238
12. SPONSORING AGENCY NAME AND ADDRESS
Robert S. Kerr Environmental Research Lab. - Ada, OK
U.S. Environmental Protection Agency
Post Office Box 1198
Ada, OK 74820
13. TYPE OF REPORT AND PERIOD COVERED
Project Report (1/90 - 4/90)
14. SPONSORING AGENCY CODE
EPA/600/15
15. SUPPLEMENTARY NOTES
Projec*: Officer: Donald C. Draper
FTS: 743-2202
16,'ABSTRACT
The main objective of this feasibility study was to test the hypothesis that properly
plugged wells are effectively sealed by drilling mud. While achieving such an objective,
knowledge of the dynamics of building mud cake on the wellbore-face is obtained, as well as
comprehension of changes that occur in drilling mud from the time it is placed in a well
until it reaches equilibrium.
A system was developed to simulate (a) building mud cake in a borehole, (b) plugging
the well, and (c) injecting salt water into a nearby well, with concomitant migration of salt
water into the plugged well. The system "duplicates" reservoir pressures, mud pressures, and
reservoir-formation characteristics that develop while mud cake is built, as in drilling a!
well. Salt-water injection is simulated, to monitor any fluid migration through thei
reservoir.
A 2100-ft. well and ancillary equipment was constructed to permit controlled measurement
and variation of simulated depth, porosity and permeability of reservoir rock, fluid
composition, fluid pressure, injection pressure, and mud properties. Data can be recorded
continuously by computer.
The in-place system provides for extensive testing of the many variables that influence
effective plugging of boreholes with drilling mud.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
CCSATi FielJ.Croup
8. DISTRIBUTION STATEMENT
RELEASE TO THE PUBLIC
19 SECURI TV CLASS i HIIV Kf
UNCLASSIFIED
;i MO OP
20 •jECuml"' CLASS , ri
UNCLASSIFIED
EPA Form 2220-1 I.R.v. 4-771
-------
DISCLAIMER
The research reported upon in this document was funded
wholly or in part by the United States Environmental
Protection Agency under cooperative agreement CR-814238 to
Oklahoma State University. The report has been subjected to
the Agency's peer and administrative review, and has been
approved for publication as an EPA document. Mention of trade
names or commercial products does not constitute endorsement
or recommendation for use.
11
-------
FOREWORD
EPA is charged by Congress to protect the Nation's land, air
and water systems. Under a mandate of national environmental
laws focused on air and water quality, solid waste management and
the control of toxic substances, pesticides, noise and radiation,
the Agency strives to formulate and implement actions which lead
to a compatible balance between human activities and the ability
of natural systems to support and nurture life.
The Robert S. Kerr Environmental Research Laboratory is the
Agency's center of expertise for investigation of the soil and
subsurface environment. Personnel at the laboratory are
responsible for management of research programs to: (a) determine
the fate, transport and transformation rates of pollutants in the
soil, the unsaturated and the saturated zones of the subsurface
environment; (b) define t£e processes to be used in
characterizing the soil and subsurface environment as a receptor
of pollutants; (c) develop techniques for predicting the effect
of pollutants on ground water, soil, and indigenous organisms;
and (d) define and demonstrate'the applicability and limitations
of using natural processes, indigenous to the soil and subsurface
environment, for the protection of this resource.
This report presents the results of research on methods for
determining the effectiveness of drilling mud as a plugging agent
in abandoned wells to assure the protection of human health and
the environment.
Clinton W, Hall
Director
Robert S. Kerr Environmental
Research Laboratory
111
-------
ABSTRACT
The Hazardous and Solid Waste Amendment of 1984 requires
the Environmental Protection Agency to assess environmental
suitability of liquid-waste injection into subsurface rock.
Accordingly, the reaction among injected wastes, reservoirs,
and original formation fluids is under evaluation.
The main objective of the feasibility study described here
was to test the hypothesis that properly plugged wells are
effectively sealed by drilling mud. While achieving such an
objective, knowledge of the dynamics of building mud cake on
the wellbore-face is obtained, as well as comprehension of
changes that occ^r in drilling mud from the time it is placed
in a well until it reaches equilibrium.
A system was developed to simulate (a) building mud cake
in a borehole, (b) plugging the well, and (c) injecting salt
water in. a nearby well, with concomitant migration of salt
water into the plugged well. The system "duplicates" reservoir
pressures, mud pressures, and reservoir-formation
characteristics that develop while mud cake is built, as in
drilling a well. Salt-water injection is simulated, to monitor
any fluid migration through the reservoir.
A 2100-ft. well and ancillary equipment permit controlled
variation of simulated depth, porosity and permeability of
reservoir rock, fluid composition, fluid pressure, injection
pressure, and mud properties. Data can be recorded
continuously by computer.
The synthetic-sandstone reservoir is cylindrical, 3 ft. in
diameter and 2 ft. thick. It has porosity and permeability
similar to those of several natural reservoirs.
Pressures commensurate with those in 5000-ft.-deep wells
were to be measured; associated differential pressures were
required. A system developed to measure differential mud
pressures includes undiminished pressure-transmittal by
diaphragm-interface.
Also, a high-pressure, low-flow-rate, high-accuracy flow
meter system was developed to monitor the slightest amount of
fluid movement. Flow meters were developed to measure (a)
fluid from the reservoir, (b) mud-column flow from above the
reservoir, and salt water being injected.
An in-place system provides for extensive testing of the
many variables that influence effective plugging of boreholes.
iv
-------
NOTICE
THIS DOCUMENT HAS BEEN REPRODUCED FROM
THE BEST COPY FURNISHED US BY THE SPONSORING
AGENCY. ALTHOUGH IT IS RECOGNIZED THAT CER-
TAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RE-
LEASED IN THE INTEREST OF MAKING AVAILABLE
AS MUCH INFORMATION AS POSSIBLE.
-------
CONTENTS
Foreword.
Abstract.
Figures .
Tables
Section 1.
Section 2,
Section 3.
Section 4.
Section 5.
Section 6.
Section 7.
Appendix A.
Appendix B,
Appendix C.
Introduction
Conclusions ........
Recommendations ........
Test Facility, Development and Function .
Introduction ........
Components Simulating the Wellbore Above
the Zone of Fresh Water. . . .
Simulated Water-reservoir Zone
Simulated Wellbore and Injection Zone
Below the Reservoir
Instrumentation Design and Application
Introduction ........
Instrumentation Design Features ...
Applications of Instruments .
Data-acquisition System ......
Introduction .
Remote Multiplexer. .......
Computer .
Software .
Flow-meter Controller ......
Test Results ........
Introduction ........
Porosity Tests . ,
Permeability Tests. . .
Drilling-fluid Tests ......
Associated Drawings and Development for the
Upper Wellbore Simulation .
Drawings and Development Associated with the
Artificial Reservoir ......
Simulated Lower Wellbore Drawings
111
iv
vii
xi
1
2
3
4
4
7
11
17
20
20
20
24
25
25
25
26
27
27
29
29
29
31
32
34
38
76
-------
Appendix D. Instrumentation Drawings and Development . 82
Appendix E. Instrumentation Calibration . . . . . 92
Appendix F. Development of Test Facility - Overview . . 109
Appendix G. Quality Assurance Plan 128
Appendix H. Operating Procedures. . . . . . .142
VI
-------
FIGURES
Number Page
1. Representative injection and abandoned well . . 5
2. Plan-view schematic drawing, test facility . . 6
3. Functional schematic drawing, test facility . . 8
Al. Simulated wellbore - mud column . . . . . 35
A2. Mud-column flow-meter assembly . . . . . 36
A3. Detailed drawing of parts, -mud-column flow meter . 37
Bl. Vials of components of artificial reservoir . .39
B2. Disc of hardened resin, cement of reservoir ... 40
B3. Standard Proctor mold and hammer . . . . . 41
B4. Bench-test samples, artificial reservoir . . . 43
B5. Model of artificial reservoir 44
B6. Plot, porosity vs. permeability ..... 45
B7. Artificial-reservoir housing . . . . . . 46
B8. Interior, artificial-reservoir housing ... 47
B9. Artificial reservoir, nearly completed ... 48
BIO. Blind flange, artificial-reservoir housing . . 50
Bll. Tabs, polycarbonate gasket material .... 51
B12. Compression test, artificial reservoir ... 52
B13. Tensile-strength test, adhesive material ... 53
B14. Placement of artificial reservoir rock ... 63
B15. Artificial-reservoir housing with end pieces . . 64
B16. Locations, reservoir-housing effluent lines . . 66
B17. Configuration, reservoir-housing effluent lines . 67
vii
-------
B18. Water and mud connections and well-head
configuration below artificial reservoir ... 68
B19. Support stand, artificial-reservoir housing . . 69
B20. Adjusting jacks, artificial-reservoir stand . . 70
B21. Details, supports for reservoir stand . . . 71
B22. Cross-member configuration, reservoir stand . . 72
B23. Gusset details, reservoir-housing stand ... 73
B24. Dimensions for cutting of pipe for welding . . 74
B25. Assembly stand, artificial-reservoir housing ... 75
C-1A. Well-head configuration, tubing and casing . . 77
C-1B. Tubing adapter, salt-water injection system . . 78
C2. Location, tubing and instruments, Test 1 . . . . 79
C3. Location, joints of 5 1/2-in. casing .... 80
C4. Location, joints of 5 1/2-in. casing .... 81
Dl. Detail, diaphragm housing, mud-water interface . 83
D2. Configuration, above-ground pressure transducers . 86
D3. Configuration, pressure transducers on
5 1/2-in. casing ......... 87
D4. Flow-meter piston assembly ...... 88
D5. Magnet/piston assembly, effluent and
salt-water flow meter ....... 89
D6. Temposonics linear-displacement transducer and
magnet/piston for effluent and salt-water
flow meters .......... 90
D7. Flow-meter assembly, effluent and salt-water
systems ........... 91
El. Overview, pressure- and differential-pressure
calibration process, Conoco, Inc. . . . . 93
E2. Computer system used in calibration .... 94
viii
-------
E3. Instrument lead-lines, transducers, multiplexer
and voltmeter used in calibration .... 95
E4. Differential-pressure transducer pressure-
equalization network 96
E5. Overview, flow-meter calibration system ... 99
E6. Computer, multiplexer, power supply and
leads for calibrating flow meters. .... 100
E7. Instrumentation Console, with flow meters. . . 101
E8. Back side, Instrumentation Console .... 102
E9. Electronics, flow-line connections, and
controls, mud-column flow meter ..... 104
E10. Simulated Wellbore - mud column ..... 105
Ell. Electronics, flow lines, controls and line
configuration for calibration, effluent
flow meter 106
E12. Electronics, flow lines with configuration
for calibration of salt-water flow meter . . . 107
Fl. Mud-plug facility 112
F2. Salt-water tank and effluent tank .... 113
F3. Mud pump, pipe network, tank, and
mixer system . . . 114
F4. V-door, pipe rack, casing and turbine . . . 116
F5. Simulated well-bore and mud-column section . . 117
F6. Artificial-reservoir system in environment-
control building 118
F7. Artificial-reservoir housing assembly . . . 119
F8. Peripheral effluent lines and instruments,
artificial-reservoir housing ...... 120
F9. Lowermost joint of casing, with instrumentation . 122
F10. Bottom end, lowermost joint of casing . . . 123
IX
-------
Fll. Pulling unit and well site ...... 124
F12. Well configuration for placement of water
and mud in casing, through tubing . . . . 125
F13. Multiplexer mounted on casing ..... 126
F14. Heat pump and computer inside instrumentation
building ...... 127
Gl. Sequence of events during one cycle
of injection tests ........ 140
-------
TABLES
Number Page
Dl. Diaphragm-seal test results ...... 84
El. Calibrated test results ....... 97
Gl. Test variables, tests 1 through 6 .... 129
XI
-------
SECTION 1
INTRODUCTION
The Environmental Protection Agency is required by the
Hazardous and Solid Waste Amendment of 1984 to assess the
environmental suitability of injection of liquid wastes into
subsurface formations. The Agency's appro'ach to this matter is
composed of three general activities: (1) to evaluate the
construction of injection wells and the capability for
monitoring them, in order to detect failures, (2) to assess the
relationship among the rock-stratigraphic units, the fluids
injected, and the integrity of the bounding confining beds, and
(3) to evaluate the reaction among the injected waste, the
formation, and the formation fluids.
The primary objective of the research described here is to
test this hypothesis: Drilling mud in abandoned, properly
plugged wells effectively seals the borehole. Therefore, if
fluids injected into reservoirs at depth were to migrate up the
boreholes of properly plugged wells, filter cake nevertheless
would prevent passage of these fluids into other reservoirs.
The alternate hypotheses need no elaboration.
A 2100-ft. well and ancillary facilities are described in
'pages that follow. This system permits controlled variation of
simulated down-hole conditions, including depth, porosity and
permeability of reservoirs, compositions of fluids, pressures
of fluids, injection pressures, and properties of plugging
agents. Instrumentation was designed and assembled, or
manufactured, in order to test the feasibility of monitoring
variation in pressures and rates of flow of fluids, under
several regimes of injection. Computer software was written
for continuous reception and recording of data. Methods were
developed for construction of an artificial sandstone
reservoir; porosity and permeability of this reservoir and some
actual reservoirs are similar.
-------
SECTION 2
CONCLUSIONS
1. Feasibility of designing and equipping a shallow well
for the purpose of the experiment has been demonstrated.
2. A technique and hardware were developed to measure
down-hole pressure gradients accurately.
•
3. A multiplexer to transfer data from down-hole to the
surface was designed and built, as were a computer board and
software, to process and store data.
4. Other equipment designed, built and developed included
a diaphragm-seal housing assembly, a temperature-sensor
circuit, a flow-meter and flow-control system (for uncommonly
low rates of flow at high pressure), and a mud-maintenance,
mud-flow network and control system.
5. An artificial reservoir with lithic properties, porosity
and permeability similar to actual injection-formations was
constructed, complete with housing and attendant
instrumentation. After initial guidance by Halliburton
Company, techniques were developed for composing, mixing,
emplacing and consolidating reservoir material, to obtain
porosity and permeability within specified limits. Moreover,
methods were developed to isolate and measure radial flow
through the large artificial reservoir.
6. A cased-well system, designed and constructed, allows
simulation of conditions below the artificial reservoir of
depths as great as 2000 ft., and controlled injection of fluids
at depths of 100 to 2000 ft. The facility could, and should,
be used to define the entire array of critical conditions of
mud-plugging. Also, it should be employed for experimentation
and development of new products and techniques for protecting
fresh-water aquifers.
-------
SECTION 3
RECOMMENDATIONS
Developments of a unique facility are essentially
complete. The facility will allow investigation of many
phenomena associated with wells, reservoirs, fluids and methods
of measurement. To utilize this facility for tests to include
but not be limited to the following topics is recommended.
1. Test the existent artificial reservoir, despite the
fact that it seems to be fractured. Build mud cake on it and
determine the amount of mud and the invasion required to build
the mud cake. Test the adequacy of the mud cake to resist
invasion under injection at various pressures.
2. Complete a series of tests to determine the
performance-envelope of parameters that could affect the
plugging and protection of a rock formation. This would
include various mud properties, various injection-fluid
properties, various reservoir porosity and permeability values
(including fractured layers), various combinations of
injection-zone and protected-zone depths and injection
pressures.
3. Develop a tool and associated instrumentation which
could be inserted into an abandoned, plugged well, and determine
the in-place mud properties. These properties, in conjunction
with the results of Recommendations 1, above, could provide a
method to estimate the adequacy of fluids in plugged wells.
4. Investigate additives that could enhance the mud-
plugging of high-porosity zones and fractured zones. These
could be evaluated during the mud-cake build-up period and then
during injection of disposable fluids.
5. Determine the effect of leaching in mud-plugged wells
and the conditions that allow the phenomenon to occur.
-------
SECTION 4
TEST FACILITY DESIGN, DEVELOPMENT AND FUNCTION
INTRODUCTION
DESCRIPTION OF FACILITY
The facility is designed for testing under conditions that
simulate a well plugged with mud, for abandonment. A zone in
the upper region of the hypothetical well is an underground
source of drinking water (protected zone, Figure 1), and the
intention is to not contaminate it. Below the fresh-water-
bearing formation is a formation used for injection (Figure 1),
pressurized by disposal of salt water into a nearby well.
Pressure is translated through the injection zone to the
abandoned well. Therefore, a potential exists for the salt
water to migrate up the welibore and invade the underground
source of drinking water. The purpose of the testing design is
to determine the array of conditions that could allow invasion
of the zone of drinking water to occur.
The testing facility is divided into four basic areas,
which are associated with zones in a plugged and abandoned
well, shown diagrammatically in Figure 1. These areas are
dedicated to study of the welibore above the reservoir being
protected (region 1), the protected reservoir and welibore
(region 2), the vellfcore below the protected reservoir, and the
salt-water disposal reservoir (region 3), and the overall part
of the facility that simulates drilling the well and building
mud cake on the wall of the welibore. Regions 1 and 2 shown in
Figure 1 are simulated by facilities located above ground
level, whereas region 3 is an actual well, 2100 ft. deep. The
part of the facility that simulates building of mud cake is
also above ground.
In the following sections, the various components or
assemblies that combine to form the facility are discussed.
Included is a brief description of each component, statement of
its purpose, salient design features, description of its
interaction or connection with other components or assemblies,
controlling features, associated instrumentation and the type
of data produced.
TOTAL-FACILITY SCHEMATIC DIAGRAM
Figure 2 is a plan view of the facility. Individual
systems are required to obtain quantitative data on results of
injecting salt water into a reservoir and the effects of
-------
SALT WATER
INJECTION
CASED SALT
WATER DISPOSAL
WELL
GROUND
LEVEL
INJECTION
ZONE
REGION #1
REGION #2
REGION #3
Figure 1. Representative injection and abandoned well.
-------
OSU PETROLEUM TECHNOLOGY
EPA PROJECT
WELL SITE LOCATION LAYOUT
Figure 2. Plan-view schematic drawing of test facility,
-------
invasion on a shallow, fresh-water-bearing formation in nearby
abandoned well. The Instrumentation Building houses the
computer used for data acquisition. About 15 ft. east of the
building, at the site labelled "Artificial Reservoir" (Figure
2) is the Instrumentation Console, the main source of test
data. The Assembly Stand (Location A, Figure 2) is the
mounting stand for the reservoir housing, used when the
artificial reservoir material is poured and for determining
porosity and permeability of the reservoir. The salt-water
tank, lines and pump, effluent tank and connecting lines, mud
tank, mud mixer, mud pump, controls and pipe network are•
clustered in the northeastern part of the facility (Figure 2).
Casing and tubing are stored on the pipe rack, and are moved to
Location B through the v-door on the northern part of the pipe
rack.
Figure 3 is a functional schematic drawing of the system.
It shows the general configuration of the components, their
interconnections, controls and instrumentation. Groupings of
these components will .be referred to in the following
discussion.
COMPONENTS SIMULATING THE WELLBORE
ABOVE THE ZONE OF FRESH WATER
INTRODUCTION
In actual wells, the wellbore above the protected zone
(Figure 1) is to be filled with drilling mud and capped with a
cement plug. The specific requirements are in regulations set
out by the States. The simulation described herein is designed
according to the well-plugging requirements of the Oklahoma
Corporation Commission. Pressure on the wellbore would be
dependent upon mud weight and depth in the well. Therefore, to
simulate the depth of a formation it is sufficient to impose a
pressure commensurate to the value determined by mud weight and
depth. Because the cement plug is stationary, but because the
mud below it can move down the wellbore and into formations
under less pressure, it is necessary to provide fluid
sufficient to simulate this condition. Also, pressure must be
maintained during movement of fluid down the wellbore. As
pressure increases in the wellbore due to injection, the mud
would move against the cement plug, and pressure in the entire
wellbore would increase. This condition also must be
simulated.
-------
Epa Project
Mud Plug Feasibility Test
Figure 3. Functional schematic drawing of test facility.
-------
SIMULATED WELLBORE-AND-MUD COLUMN
A section of 7-in. casing was sized to hold enough mud to
sweep about one-half the pore volume of the most porous medium
that we expected to test (container at "High Point Air Bleed,"
Figure 3). This amount of mud is expected to place a final
seal on the mud cake (if indeed the extra mud is required)
after circulation of mud through the wellbore. If one
container-full is insufficient, then the valve arrangement is
designed so that the container can be refilled during the test,
with minimal disturbance of test results. When the mud column
is filled with mud and air is bled from the system, then the
nitrogen pressure is adjusted to make pressure in casing above
the artificial reservoir be commensurate to pressure in an
abandoned well, at the given depth. This nitrogen pressure is
impressed upon water in the mud-column flow meter and
transmitted through the line between the flow meter and the
simulated wellbore-mud column. If the fluid level moves, fluid
either has gone out the effluent line or out a leak in the
system. The system is designed so that data from the three
flow meters will determine whether a leak exists or fluid is
being discharged to the effluent tank.
Appendix A contains a drawing and specific information
about design of the simulated wellbore-mud column. Some of the
design features associated with this part of the system are a
fill tee and bleed valve at the top of the column, a flow tee
and three valves at the bottom of the column, and a line
connecting the column to the flow meter and to a check valve
and a shut-off valve on the flow meter end (See diagram near
"High Point Air Bleed" container, Figure 3).
During filling operations the valve next to the check
valve (to the left of check valve, top-center, Figure 3) is
closed so that mud will not get into the check valve. Before
mud is placed in the column, the line from the flow meter is
filled with water. The high-point air-bleed valve on top of
the column is open and the two in-line valves in the flow tee
below the auxiliary mud container are open, but the leg of the
tee to the mud tank is closed. Mud pumped slowly from a line
connected to the bottom of the reservoir flows up the casing
until all water in the casing is forced out, and only mud
remains. At this time the high-point air-bleed valve is closed
and the' mud-tank return-line leg of the tee is opened. With
this condition the system is ready for other operations, such
as building mud cake, impressing pressure to begin the
equilibration phase, or to maintain pressure during the
injection phase.
-------
If, during operation, mud in the simulated wellbore-mud
column has been replaced by water from the flow meter,then the
in-line valve on the bottom of the bottom tee (Figure 3, atop
the casing-stem that projects from top of artificial reservoir
and below tee on mud-tank return line) must be closed and the
valve adjacent to the check valve must also be closed. Upon
opening the high-point air-bleed valve, pressure will cause
fluid to flow into the temporary line connected to the effluent
tank. Valves in the mud-line network are then adjusted to
route mud from the mud pump to the cross-flow leg of the bottom
tee ("Mud Tank Return Line," Figure 3). Mud is pumped until
the column is full.
MUD-COLUMN FLOW METER
A set of design drawings for the mud-column flow meter is
in Appendix A, along with some design information. Additional
information is in Appendix F, in connection with the wheel-
mounted instrumentation console. A section of 7-in. casing was
used to make the body of the flow meter. This flow meter is
mounted vertically and has a Temposonics linear-position
transducer that extends from end to end in the body. A magnet
is attached to a float that indicates the location of the fluid
level (Figure A2) and the differential position of the float is
calibrated to give flow rate. On the top of this vessel is a
nitrogen line that is connected to a regulator and high-
pressure nitrogen bottle. Also on the top of this vessel is a
fill port for water. The flow meter monitors the flow rate
from the mud column and for control, also transmits nitrogen
pressure to the column. A nitrogen regulator maintains the set
pressure of the mud column even though the rate of flow may
vary.
For the case where the injection pressure causes pressure
at the reservoir to become more than the set nitrogen pressure
— which is the simulated wellbore pressure — then mud begins
to move up the column until the check valve at the bottom of
the flow meter stops flow and simulates backing-up against a
cement plug. At this point the injection pressure controls
pressure in the wellbore, just as it would in an actual well.
This simulated wellbore-mud column is very important in
simulations of drilling operations to build a mud cake on the
walls of the reservoir. These details are given in the section
of this report entitled "Simulation of Drilling Process to
Build Mud Cake," on page 16.
10
-------
SIMULATED WATER-RESERVOIR ZONE
INTRODUCTION
An abandoned well necessarily has gone through a drilling
stage and then the plugging stage. The simulated condition
must follow the same steps. First, the reservoir is filled
with water under the pressure commensurate with the depth being
simulated. Then the drilling operation is simulated by
•circulating mud from bottom to top past the porous medium,
which is maintained at reservoir pressure. Mud in the column is
maintained at the pressure appropriate for depth of the well
and density of the mud. This process is continued until the
mud cake is fully developed — when there is no more flow of
filtrate into the artificial reservoir. In the test this is
determined by the flow meter that measures effluent from the
reservoir.
Flow is radial from the wellbore into the reservoir; thus
a cylindrical section was used to simulate the reservoir. A
medium with permeability and porosity similar to those of
natural reservoir rock is necessary for accurate simulation.
Radial, non-converging planar flow from the wellbore outward is
required to be similar to that in a large-volume'reservoir.
This was accomplished by pouring a mixture of resin and graded
sands into a cylindrical housing. This process is described in
Appendix B; see especially Figures B5 through B9.
This artificial reservoir was poured in two steps. The
first was a 1-in, shell in the outer periphery of the
cylindrical housing. This is a coarse-grained, highly
permeable synthetic sandstone that has very little resistance
to flow. The main part of the reservoir is a vertical-walled
cylinder with flat top and bottom; the outer walls are bonded
to the outer, highly permeable shell and to the top and bottom
flanges of the steel reservoir housing.
A borehole in the center of the cylinder is the same size
as the casing that simulates the wellbore. A bonded interface
between the top of the reservoir housing and the rock and the
bottom of the housing and the rock is required to insure that
flow does not take a path having different permeability than
the rock. Because permeability of the outer shell is much
larger than the that of the core of the reservoir, then the
axial (vertical) pressure gradient is very small and the
driving force comes from the radial pressure difference between
the wellbore and the outer shell. Therefore, flow would be
planar and radial. To assist in maintaining this planar,
radial flow in the core of the artificial reservoir 24 holes
11
-------
are distributed around the side walls of the cylinder. This
series is shown schematically in Figure 3.
An explanation was given of how mud pressure in the
wellbore is to be maintained to simulate conditions in the
well. The artificial-reservoir pressure must also be
maintained, but independently of the mud pressure. In large
reservoirs, at places distant from the borehole, virgin
reservoir pressure is maintained until a large amount of fluid
is injected into the reservoir. Because a virgin fresh-water
reservoir is simulated in the case at hand, and because this
reservoir pressure would influence the full development of mud
cake, then a constant reservoir pressure must be maintained.
Pressure is developed by a nitrogen-filled accumulator bladder
in contact with tn.e effluent water. The nitrogen pressure
regulator maintains pressure at the desired value, which is
just below the reservoir pressure. A high-precision pressure-
regulated bypass valve is set at the reservoir pressure so that
when, or if, pressure of the core fluid becomes greater than
that in the virgin reservoir, the bypass opens and flow exists
but pressure is maintained. Controls to achieve this constant
reservoir pressure are shown schematically in Figure 3.
ARTIFICIAL-RESERVOIR HOUSING
The largest feasible artificial reservoir was desired.
Expense and handling-operations were the limiting factors. The
resulting dimensions of the reservoir housing are 2 ft. in
height and 1 ft. in diameter. The housing had to be strong
enough for high-pressure operation, to allow simulation of a
range of reservoir depths. Along with the pressure
requirements, the housing was designed to permit emplacement
and replacement of artificial rock,to give the capability of
using a sequence of different reservoirs. The final design
used welded flanges on a 3-ft.-diameter pipe section with
mating modified blind flanges on the top and bottom. With the
flanges that were used in the design the allowable operating
pressure is 1450 psi, which translates to an equivalent depth
of aJbout 3000 feet. This pressure required that the flange
bolts be torqued to 2500 foot-lbs. A 5-1/2-in. casing sub was
welded in the center of each of the two modified blind flanges.
These are to simulate the borehole and to provide a means of
connecting to the upper simulated wellbore-mud column and the
lower wellbore. Design drawings .and design information are
given in Appendix B.
Associated with this housing is a hose system, to provide
a path for fluid forced out of the reservoir to be directed to
the effluent tank (Figure 3). These hoses were sized to insure
that the pressure drop attributed to these were much less than
12
-------
the pressure drop through the reservoir, for the range of flow
rates expected in the reservoir. The number and array of these
hoses were designed to give relative uniform flow along the
side walls of the housing. In addition, positioning of hoses
was to allow a wrench to be placed on the flange nuts and to
minimize entrapment of air in the lines. Flexible lines were
used to accommodate the compound curvature when going from row
to row.
In order to minimize path of flow and provide a simulation
of drilling, a 2-in. line for the mud-pump connection is
welded to the 5 1/2-in. casing sub at an angle to the axial
line of the casing and tangent to the wall of the casing. This
will cause the fluid to take a spiral path up the casing, to
simulate the. rotation of drill pipe in the borehole (Figure 3,
below bottom blind flange).
Another line connection is welded on the lower 5 1/2-in.
casing sub, but above the mud-pump connection (In Figure 3,
elliptical dot on casing suJb, a few inches below, bottom flange
of reservoir housing.). This is to provide a source of fluid
to run permeability tests. It is above the mud-pump
connection, so space is available between the two to place an
inflatable plug in the line; this plug is to keep the reservoir
from being drained when the bull plug on the bottom end of the
casing is removed in preparation to connect to the casing in
the hole. The inflatable plug is removed by the mud's
displacing it out the top, to keep from affecting the water in
the reservoir. If sufficient deflation of the plug can be
accomplished, an alternate removal method is to pull the plug
out slowly with a wire line, to allow replacement of the
displaced volume with water from the upper 5 1/2-in. casing
sub.
Hammer unions in the upper and lower casing subs are
required because of the need to assemble and disassemble in
close tolerances without rotating the casing.
Inforriation from this reservoir housing is acquired with
differervcial-pressure transducers, pressure transducers,
temperature sensors and a flow meter. To determine the
pressure gradient across the reservoir-in the axial direction a
differential-pressure transducer was mounted was mounted on the
casing pup just above the upper modified blind flange; pressure
lines are connected to a diaphragm housing above the top flange
and to one below the bottom flange. Information gained from
this transducer is change in pressure drop during mud cake
build-up, and change in fluid gravity during static tests and
salt-water injection tests.
Three differential-pressure transducers are manifolded,so
13
-------
each can be isolated when the radial pressure gradient goes out
of its range. To maintain good accuracy at all pressure
differences it was necessary to have one transducer measure
from 0 to 50 psid, one from 0 to 250 psid and the third from 0
to 1000 psid. Pressure differences will increase as the
injection pressure increases and the test can not be shut down
or interrupted to change transducers. These will measure the
pressure from the same diaphragm housing above the top flange
to the radial effluent line. These data, in conjunction with
the axial differential pressure, will provide the reservoir
radial pressure gradient. This gradient will be used for
permeability calculations and for correlating the potential
invasion flow rate across the mud cake.
A pressure transducer is mounted on the casing sub above
the top flange; its purpose is to monitor the mud-column
pressure. A temperature sensor is mounted in the same general
position. These two values and the axial pressure gradient
will define the state of the mud in the casing sub.
The effluent line goes'to a flow meter, which measures
from about 0.0005 gallons per hour to about 32 gph. Included
with this assembly is a back-pressure valve that is set to
control the back pressure precisely. Adjacent to it is an
accumulator that is operated from a regulated nitrogen bottle,
to initialize the reservoir pressure and adjust to the desired
value. From the outlet of the back-pressure valve, fluid goes
to a tank that contains the effluent until it is properly
disposed of.
SIMULATED RESERVOIR ROCK
Actual reservoir material has a large range of
permeabilities and porosities. A single value was,chosen for
each of these properties for the first test, but the capability
exists to simulate a broad range of values. A detailed account
of the development process to achieve the design requirements
is in Appendix B.
Figure B9 shows the reservoir rock in an intermediate
stage of the reservoir development. The dark-colored rock is
the highly permeable rock shell that was discussed above; the
light-colored rock was mixed and emplaced to have the designed
porosity and permeability. The center mold forms the "well
bore". Of course the cylinder was filled completely with the
light-colored material, which was bonded to the top flange
gasket. The center form is removed after the top flange is
placed on the cylinder and the material has cured. A high-
density polyethylene liner is between the wall of the cylinder
and the outer high-permeability shell, to allow easy removal of
14
-------
the reservoir rock from the cylinder after tests are run.
Resin will not adhere to the liner and the rock will slide out.
This liner must be penetrated to allow fluid to flow from the
24 ports to the effluent flow meter. The high-pressure
flexible- hose connections were designed to allow easy access
for drilling these holes in the liner.
Rock Porosity and Permeability Measurements
The porosity-measurement technique begins even before the
artificial rock is placed in the reservoir housing. With the
housing completely assembled and a bull plug on the bottom of
the attached 5 1/2-in. nipple, the void is filled with water by
pouring from a 1000-ml. graduated cylinder. This yields the
bulk volume. After the artificial rock is placed in the
reservoir housing, the void space is filled with water from the
peripheral effluent lines, through the salt-water-injection
flow meter assembly. Knowing the overall dimensions of the
rock placed into the housing, along with the two water volumes
and the porosity of the coarse rock, allows determination of
the porosity of the simulated reservoir rock. The coarse
outer-shell porosity was determined from the Amoco sample
porosity tests.
After the tests are run and the artificial rock is
removed, then samples are to be taken from the rock and these
samples are evaluated for values of porosity, permeability and
mud content.
When the reservoir is full of water, then the steps to
measure permeability can take place. The line from the
saltwater-injection flow meter is connected to the 1/2-in.
fitting welded to the 5 1/2-in. casing nipple. The effluent
line is connected to the effluent tank. A flow rate is
established by adjusting the pressure differential across the
reservoir radius. This is done by adjusting the back-pressure
valve orv the effluent line and the nitrogen pressure in the
associated bladder. By measuring the flow rate, pressures,
differential pressures, temperatures and obtaining the
viscosity of the water, then permeability can be calculated.
Measurement of porosity and permeability is discussed
under Operating Procedures 6.1 and 6.2, Appendix G. It should
be noted that after these tests are conducted, then the
artificial reservoir housing must be moved, centered over the
well, and connected to the casing string. The assembly stand
(.Location A, Figure 2) is designed to make this transition; the
four legs have adjustable jacks to provide easy connection with
the casing (without unseating casing from the slips).
15
-------
SIMULATION OF DRILLING PROCESS TO BUILD MUD CAKE
During the drilling operation the mud pressure coming
through the drill pipe, drill bit and up the annulus must be
sufficient to move the fluid against the head pressure and also
to overcome friction. Because of this, the pressure to build
mud cake is higher than the static pressure of mud sitting in
the hole. Initially the reservoir being penetrated has
inherent pressure, then the reservoir is exposed to the
stagnation pressure of the flowing mud and then to the flowing
static pressure. The sides of the wellbore are subjected to
mud at the flowing static pressure over the greatest period of
the drilling operations. Thus mud cake in the test procedures
described here is to be done at this flowing static pressure.
This will create a different pressure differential to form the
mud cake at each reservoir depth in the test series.
A pressure-operated bypass valve is in the mud-line
network to keep over-pressurization from occurring during
start-up and operation. Prior to mud being circulated to build
a mud cake, it is necessary to have the test-simulated wellbore
full of mud. Pressure in the reservoir is to be brought up
slowly to equal the virgin reservoir pressure by adjusting the
accumulator pressure in the effluent flow meter system and
simultaneously adjusting the nitrogen regulator in the mud-
column flow meter, to make the mud-column pressure equal to the
reservoir pressure.
During this pressure build-up time, valves in the mud flow
lines coming from and returning to the mud tank are closed at
the wellbore connections (Figure 3). Concurrently the mud pump
circulates mud through the bypass valve, which was pre-adjusted
to a specified increment above the static flowing mud pressure.
The back-pressure valve in the return line from the reservoir
must be pre-adjusted to be equal to the static flowing mud
pressure. Then when the valves leading to and from the wellbore
are opened a surge of mud will flow up through the reservoir in
a swirling fashion, which will simulate the drilling fluid
dynamics. The pressure differential between the mud and the
reservoir pressure will cause a mud cake to be built up on the
porous wall of the reservoir. Initially there will be some
flow into the reservoir to build the mud-cake. But once there
is no flow into the reservoir under these flow conditions, then
it is established that a mud cake is completely formed. This
would be determined by the effluent flow meter. How long this
process takes will be defined by the flow-meter output.
To not disturb the mud cake, the shut-down process becomes
important. While the mud is circulating, the mud-column
pressure source is adjusted to be equal to the static mud
16
-------
pressure (which is less than the flowing static pressure).
Then the back-pressure valve is adjusted to cause the flowing
pressure to be equal to the static mud pressure. At this
point, the supply valve is shut off and the bypass valve routes
the mud back to the tank. The return line is then shut off and
the mud is confined to the wellbore and reservoir system at the
appropriate pressure.
SIMULATED WELLBORE AND INJECTION ZONE BELOW THE RESERVOIR
INTRODUCTION
Because communication from an injection well through a
subsurface injection zone has the potential of mixing salt
water with drilling mud and considerably raising the pressure
in the mud column, it is not sufficient to simulate only the
direct effect that depth and borehole volume have on the
process. Thus it was determined to make possible a range of
depths from about. 200 ft. feet to 2000 ft. This was
accomplished by drilling the 2100-ft. well, cementing it from
bottom to top, and placing a full open head on the top casing
joint with 5 1/2-in. slips. Casing can be run in the hole to
the desired depth and hung on the casing-head slips. Rather
than drilling an adjacent well and injecting salt water in it,
hoping that some of the salt .water would get to the test
wellbore, the simulation is done by running a string of 1 1/4-
in. tubing on the outside of the 5 1/2-in. casing and supplying
salt water directly into the casing at the injection point. A
check valve is in the tubing at the injection point to allow
fluid to be supplied to the casing, but not to come from the
casing to the tubing. Specific design drawings and design
information on tubular materials and components associated with
the down-hole part of the facility are in Appendix C.
The pressure of the mud at the injection point is governed
by the pressure set for the simulated reservoir section, the
depth of the casing string in the hole, and the density of the
mud. As discussed previously, this pressure can be varied to
simulate wells as deep as 3000 ft. to the upper reservoir, and
by -adding the 2000 ft. of casing down to the injection point,
the total well depth that can be simulated is 5000 feet.
WELL CONFIGURATION
Sixteen-inch-diameter surface casing is set to 333 ft. and
cemented bottom-to-top. The long string, a 10 3/4-in. casing,
was run to 2100 ft. and cemented from bottom to top with light
cement.
17
-------
Screwed to the 10 3/4-in. casing is a 10 3/4-to-5 1/2
casing head. This is a full open head to allow all the 5 1/2-
in. inch casing and 1 1/4-in. tubing into the 10 3/4-in.
casing. The slips were modified to allow the instrumentation
lines and salt-water injection tubing to pass through while the
casing is set in the head. A transition piece was made to
reduce the 1 1/4-in. tubing to 1/2-in. tubing and a 1/4-in.
tubing for venting purposes.
In order to simulate any depth between 100 ft. and 2000
ft., the 5 1/2-in. casing and the 1 1/4-in. tubing is run into
the hole simultaneously until the injection point is reached.
At that depth, the casing is set in the head.
MEASUREMENT AND CONTROL
Injection pressure for the saltwater is supplied by an
accumulator with nitrogen in the bladder and the column head of
salt water going to the injection point. The accumulator
forces fluid -through a flow meter and into the line going to
the injection point. If the pressure is sufficiently high then
flow will exist; otherwise the pressure will be statically
impressed upon the mud column. A detailed set of drawings and
design information for the flow meter and controls is set out
in Appendix F.
In order to determine the mud characteristics and dynamic
behavior of the mud column in the injection area, a sequence of
differential-pressure transducers was placed on the 5 1/2-in.
casing and run down-hole. Strategically placed pressure
transducers and temperature sensors were also placed on the
pipe. Considerable design and search was required to
accomplish this task. Original design concepts were to run
each wire from the individual sensor to the top of the
borehole, but this became quite problematic after calculation
of dimensions and weights, and review of the required
operations. An application from Oklahoma State's space
research resolved the problem, through design of a multiplexer
that required only one cable from the surface. Multiple
sensors would be attached to it from a series of locations
below the multiplexer. The multiplexer can serially select a
given sensor and send that part of the signal up-hole, cycle to
the next and repeat the operation until all sensors are
sampled; then the cycle repeats. On the surface a computer
program sorts the data and stores it in an array for further
use. These instruments and controls are shown in detail in
Appendices D and E.
Information from the down-hole instrumentation provides a
means of determining the average properties of mud in sections
18
-------
of the pipe defined by the pressure connections on the
differential-pressure transducers. The rate of change of these
properties would yield information about the dynamics of
equilibration in plugged wells and of wells having injection
fluids impinged upon a long mud column. Specific locations of
the instruments are shown in drawings in Appendix C.
19
-------
SECTION.5
INSTRUMENTATION DESIGN AND APPLICATION
INTRODUCTION
Instrumentation design includes the design of the system
of sensors, the selection of components and the design of the
instrument itself, in some cases. In the case of flow meters,
many hours of searching the literature for various sensors
failed to provide instruments that would fit all the criteria.
Also, literature was searched for differential-pressure
transducers that had the accuracy, line-pressure range and
small size to satisfy the constraints of the project. A
discussion of these features will be covered in this section of
the report. Specific design drawings are in Appendix D.
INSTRUMENTATION DESIGN FEATURES
TEMPERATURE SENSORS
The temperature sensors were selected on the basis of
accuracy, stability and signal output. The unit chosen was the
AD 590 KF temperature sensor, which yields a high current
output. Accuracy and linearity were enhanced by designing a
circuit to cover the design range expected in the test series.
Accuracy of the sensors,-as designed, is about 0.3 deg. C.
DIAPHRAGM HOUSING
Two problems existed that resulted in design of the
diaphragm-seal housing. Some of these problems arose because
of the small lines connecting the pressure transducer to the
pressure source. First, mud in the system has a potential of
being in a different mixture as time changes; therefore we can
not rely on knowing the properties as a standard. Secondly,
the potential existed of mud's hardening in small lines and
affecting the pressure measurements. In addition, mud and salt
water, which could get into the pressure lines, could have
detrimental effects on the transducer material — unless, of
course the material were corrosion-resistant.
During verification of the differential-pressure
measurement technique it was found that in the transition from
atmospheric pressure to 3000 psi, air in a line will compress
to less than 2 percent of its original volume. Therefore, air-
to-mud interface in an instrument line is not feasible for high
pressures. Further calculations showed that water will
20
-------
compress in a 1/4-in. tubing to the extent that a displacement
takes place of about 3.5 in. in a 30-ft.-long tube when
pressure increases from atmospheric to 3000 psi. These
circumstances led to design of the bellows diaphragm. A
Bellofram rolling diaphragm was chosen to eliminate essentially
any resistance to transmitting pressure, so that an accurate
measurement can be achieved. The volume of the half-
displacement was selected to be equal to the 3.5-in.
displacement in a 1/4-in. tubing. The final configuration,
shown in Figure Dl, is to fit the contour of the pipe, keep air
bubbles from being trapped, fit in the annulus in the well,
allow replacement of the diaphragm, seal the pressure, and
adapt to the plumbing requirements. Applications of this
diaphragm are shown in Figures H7 and H8.
PRESSURE TRANSDUCERS
A search of commercial pressure-transducer sources
revealed that most designs on the market are not conducive to
placement in a small annulus. There were several choices but
some were eliminated because of the extremely long delivery
time, some because of accuracy, and some because of cost. Two
types were chosen; one is a Validyne P305A absolute-pressure
transducer and the other is an ICSensor 115 pressure
transmitter. More information is located in Appendix D.
Each of these transducers was plumbed to the diaphragm
housing with 1/4-in. tubing and fittings so that it could be
filled with vater,. to allow air to bleed from the lines. These
diaphragms were mounted on the casing or on special brackets
that provided communication directly with the fluid being
measured. Holes into the cavity of the diaphragm are
configured so that as fluid is being placed in the casing air
will not be trapped in the cavity. Also the surface where the
holes are drilled will not cause disconfiguration of the
diaphragm seals, due to the differential pressure of the
instrument fluid and the air in the casing before water or mud
is placed in it.
Pressure ranges vary for the different pressure
transducers based on the potential location in the well, the
maximum reservoir pressure anticipated, the maximum injection
pressure and the maximum simulated mud-column depth to the
upper reservoir. A list of these pressures is in Appendix D.
DIFFERENTIAL-PRESSURE TRANSDUCERS
Unlike the pressure transducers, the differential-pressure
transducers were limited to only one choice. Only the Validyne
P305D transducer would fit the accuracy, line-pressure range,
21
-------
differential-pressure spans, size and configuration criteria.
t
The differential-pressure measurements require that two
sources of pressure be tapped into. Thus, a diaphragm housing
is required at each location. The distance between the
diaphragm housings, and the density of the fluid being measured
dictate the pressure span for each transducer. The maximum
pressure expected in the vertical sources is based on the
density of bentonite. A list of pressures associated with a
given differential-pressure transducer is shown in Appendix D.
All instrument lines are configured similar to that
discussed for the pressure transducers, but the high-pressure
side of the differential transducer extends down the casing
several feet. Figure C2, Appendix C, shows lengths between the
down-hole differential-pressure transducers. This part of the
line acts as a manometer and is part of the data-reduction
equation to find the mud density; therefore density of the
fluid in this line is required.
At one point,each of the transducers is connected to the
same pressure source since the diaphragm seal is large enough
to accommodate expansion into each of the lines. Each of the
differential-pressure transducers is coupled one to another, so
that the sum of the pressure drops theoretically should equal
the pressure difference between the pressure transducers at the
two extreme ends, as a check in the readings. The measurements
are not expected to be exactly the same because the pressure
transducers measure the full value of the pressure; this
results in a different reading accuracy than for the
differential pressures.
PISTON FLOW METERS
An extensive search was made to find a flow meter that
would measure very low flows accurately while operating in a
high line pressure, and that would extend to moderate flow
rates. Because none could be found to fit the criteria, a flow
meter was designed. Several concepts were reviewed before the
design, as seen in Appendix D. The design had to allow for
continuous or intermittent flow, and measure with accuracy
flows as small as about 0.0005 gph or as large as about 32 gph.
Basically, the method is to know accurately the location of a
piston in a cylinder at a given time and at subsequent times.
In order to accomplish this a Temposonics linear-displacement
transducer was inserted into a cylinder. This transducer reads
the position of a magnet that is mounted onto a piston. A seal
is between the shaft and piston and between the piston and
cylinder wall. Displacement volume versus time results in a
known flow rate.
22
-------
To allow continuous flow, fluid moves into one end and
out the other with the piston being the interface. When the
piston gets to one end of the cylinder the flow must reverse
rapidly. To accomplish this a set of Vindum three-way, four-
position valves was purchased, which has a valve operating-time
of less than 0.1 second. For the flov-rate range concerned
with here, this has negligible effect on accuracy during turn-
around. Both valves are connected to the two ends of the
cylinder; one controls the inlet and one the outlet.
Controlling the cycle is done with a circuit that was designed
to operate off the Temposonics position signal. Output of the
Temposonics is sent to the multiplexer and stored on the
computer hard disk. Figure D is an assembly drawing of the
flow meter. There is one flow meter for effluent flow and one
for injection flow. Photographs of these flow meters are in
Appendix E.
FLOAT FLOW METER
The float flow meter operates in a vertical mode; it does
not allow continuous flow monitoring". When the fluid in it is
depleted, then the unit must be deactivated and refilled with
water before placement back into operation. To have this flow
meter in continuous flow is not critical, because the volume of
the casing that contains the meter insures an ample supply of
fluid, in most instances. This design is similar to that of
the piston flow meter, but the magnet for the Temposonics is
mounted on a float and water level is measured with time. This
unit acts as a pressure source for the simulated mud column;
nitrogen pressure is regulated to ullage above the water in the
vessel. Therefore it supplies the mud column flow potential
and measures flow when it occurs.
Output of this flow meter also is also sent to the
multiplexer and stored on the computer hard disk. Drawings of
this meter are in Figure A2; a photograph of it is in Appendix
E, Figure E10.
MEASUREMENTS OF PERMEABILITY AND POROSITY
Instrumentation discussed in the previous subsections is
applied to define the parameters necessary to calculate the
values of permeability and porosity. Pressure differences,
flow rate and temperature are used to determine of
permeability. Information from the flow meter is necessary for
the volume of liquid required to fill pores, and temperature
and pressure are used to define the state of the fluid.
23
-------
APPLICATIONS OF INSTRUMENTS
Differential-pressure transducers will supply information
on mud density; measurements by temperature sensors at the same
positions and knowledge of mud constituents will permit the
down-hole characteristics of mud to be determined.
Time history of pressure gradients will come from the
differential-pressure transducers; these will provide an
indication of when mud in a long column equilibrates.
Output of differential-pressure transducers and
measurement of local pressure will show the behavior of a
column of mud when it. is subjected to injection pressure at a
given depth.
Permeability and porosity data derived from these
instruments will supply a method of relating test data to field
•data in similar situations.
For a given formation pressure, formation depth and
permeability, flow-meter data will, determine the amount of mud
that invades a formation prior to the building an effective mud
cake.
A combination of the instruments will provide the data to
determine the amount of fluid, if any, that penetrates a
mud cake for given values of injection pressure, reservoir
depth, injection depth, reservoir pressure and permeability.
24
-------
SECTION 6
DATA-ACQUISITION SYSTEM
INTRODUCTION
The Data-acquisition System for the project was designed
and developed by the Oklahoma State University Electronics
Research & Development Laboratory. Several unique design
challenges and considerations were met in making this system
functional.
Design criteria included limitations of size and weight,
and a relative long distance to the farthest sensor.
Miniaturization of the data-acquisition system was imperative,
as size was limited to less than 2 in. of spacing between down-
hole piping. The data-acquisition system was to be "sandwiched"
between the 10 3/4-in. casing and the 5 1/2-in. casing.
Weight factors were a key consideration in development, because
the system was to be attached to the down-hole pipe. Individual
wiring to each of more than 50 sensors — as might be
considered in a standard acquisition system — would have
accumulated to too much weight in this case. With 100 ft. of
single-shielded twisted wire weighing approximately 2.3 lb.,
multiplication of this factor by the number of sensors (with
the farthest one at 2000 ft.) made this method infeasible.
With these limitations in mind, a multiplexing scheme was
developed that provided adequate sampling of each sensor and
greatly reduced the size and weight of the system.
Instruments running constantly can yield voluminous,
unwieldy data. A good data-acquisition system guards against
this situation. The system must also act as a control for
particular, potentially hazardous conditions. Because this
test system will not be attended 24 hours a day, the design of
the data-acquisition system also includes sorting and storage
REMOTE MULTIPLEXER
The remote multiplexing scheme was developed as a
derivative of a proven design used for uplink command telemetry
of a suborbital space vehicle. In the data-acquisition system,
an address is generated by the system computer, transmitted to
a remote multiplexer station where the address is decoded, and
the proper down-hole multiplexer is selected. The analog output
from the selected sensor is converted to a common O-to-20
milliampere current loop and carried to the I/O board in the
25
-------
AT-compatible computer. The current is converted into a 0 to
+10 voltage-value through a precision resistor and fed into
the computer's 12-bit Analog-to-Digital converter. This digital
value (with approximately 2.5 mv./LSB) is read and stored in a
data table. Complete acquisition control can be maintained
with this method because each sensor is selected individually.
Sensors may be "polled," with all sensors being sampled in one
cycle, or a random sampling of sensors may be selected. The
binary value of the select address corresponds to the sensor
number.
COMPUTER INTERFACE
The computer interface I/O board was also developed as a
part of the total acquisition system. Here, the computer-
generated address for selection of the multiplexer input is
encoded into a Pulse Code Modulated (PCM) bi-phase level format
for transmission to the remote multiplexer. The bi-phase
format has an inherent advantage in that the clocking can be
regenerated. By reconstructing the clock at the decoder in the
remote multiplexer, synchronized address/data transmission is
achieved. In addition to the address encoder, the current-to-
voltage converter, analog-to-digital converter and associated
logic hardware to interface with the computer are on the I/O
board.
A O-to-20 milliampere current loop was chosen for serial
sensor data transmission to the computer. With this method,
any number of remote multiplexers may be added to the single
current loop. When a multiplexer station is not selected, the
voltage-to-current converter at that station will remain in an
off or zero state and will not degrade the data sample taken
from another multiplexer.
An interface card that plugs into an IBM-AT was designed
and built to address a multiplexer input and convert the analog
data to digital data. Data are stored on a disk, scanned, and
if appropriate signals are detected, then signals are sent to
shut the system down or to sound a warning.
Two multiplexers were designed and built, one for the
instruments on the surface and the other for-'instruments down-
hole. These, multiplexers .are connected to an array of sensors
and this information is fed serially to the interface card.
COMPUTER
The computer is a PC-AT compatible with a 40-megabyte hard
disk drive, one 1.2-megabyte 5 1/4-in. floppy disk drive, and
26
-------
one 1.44-megabyte, 3 1/2-in. floppy disk drive. It has an 8287
mathematics co-processor and a Phoenix BIOS.
SOFTWARE
Software for the data-acquisition system was developed by
staff and students at Oklahoma State University using Microsoft
"C" language. Features of the software include sensor address
generation, data sample rate, conversion of the data digital-
value into volts and engineering units, storage of data,
including date-and-time stamp, and real-time display of sensors
monitored.
Under normal conditions, a binary address value is
generated, which corresponds to the sensor to be sampled. -A
software delay allows the sensor to be sampled and the analog
data to settle before conversion to digital format. Once
conversion takes place, the computer reads the digital output
of the analog-to-digital converter and stores this information
(in voltage units) on the hard disk drive. The computer
generates the next address/sensor and the process repeats. When
the computer has polled all sensors one time, a delay is built-
in to wait for approximately 10 min. before another sample is
taken. At midnight, the file of the data stored that day is
closed and named'with a date stamp. A new file is started for
the next day's data.
Data are stored in ASCII and are retrieved easily for data
reduction by many popular versions of spreadsheet software.
Although data are stored in voltage units, real-time display
can be seen in engineering units. Pressure in pounds per
square inch and temperature in degrees Centigrade provide a
handy quick-look picture of the system.
FLOW-METER CONTROLLER
The flow meter provides an analog output of 0 to +10 volts
relative to the position of the sensor inside the flow meter.
A method was designed and developed that would limit and
reverse the direction of the flow meter. This method employed a
two-level comparator circuit that compares the relative voltage
of the flow-meter sensor to a limit voltage. The limit voltages
are pre-set for each individual flow meter, with voltage, of a
few tenths of a volt being set for the lower end, and a limit
voltage of a few tenths of a volt below 10 volts for the higher
end. The comparator uses an operational amplifier
configuration for the circuit. As the flow-meter sensor
27
-------
reaches a limit, voltage from the sensor compares with the
limit voltage and drives the operation amplifier into
saturation. This provides a "high" output, which is used as a
digital input to a buffer/inverter circuit. The buffer
circuit controls the spool-valve relays which in turn control
the flow direction of the flow meter. At this point, the relays
are engaged (or disengaged) changing the direction of the flow
meter. When the flow-meter sensor reaches the opposite end,
the comparator again compares the flow-meter analog voltage
with the limit voltage, and the operation amplifier is driven
to a low state, reversing the condition of the buffer/inverter
circuit, and therefore reversing the flow of the flow meter.
The two-stage comparator will remain in a steady state,
regardless of the intermediate analog voltage as the flow meter
moves from one end to the other. Only when the analog voltage
compares with the high- or low-limit voltage will it change the
state of the controlling relays.
28
-------
SECTION 7
TEST RESULTS
INTRODUCTION
Test results discussed in this section include porosity
tests, permeability tests and preliminary abandoned- and
plugged-well tests.
POROSITY TESTS
Prior to beginning the porosity tests, the instrumentation
console was moved from the Electronics Laboratory (where a
series of calibration tests were run on the three flow meters
in series at various pressures) to Location A in Figure 2.
Because the series of flow-meter tests was not run at
atmospheric pressure, another calibration was run at Location A
to obtain the conversion from Temposonic voltage output to flow
volume. This was done with the computer recording voltages,
pressures and time, while water from the system was being
measured with a graduated cylinder. This was the same 4000-ml.
graduated cylinder that was used to measure the initial volume
of water placed in the reservoir.
Initially, the reservoir housing was assembled with all
effluent lines on the periphery, a bull plug on the bottom of
the 5 1/2-in. casing sub (Figure H7), and the valve assembly
removed (at the hammer union) from the 5 1/2-in. casing sub on
top of the reservoir housing. Using the 4000-ml. graduated
cylinder, the reservoir housing was filled to the lip on the
inside of the lower hammer-union connection, for a consistent
reference point. Milliliters were converted to gallons and the
total volume was measured as 104.20 gallons. This volume is
the bulk of all lines, connections, casing, and reservoir
housing.
After constructing the artificial reservoir in'the housing
and reassembling the system to the same external configuration
that was tested for the bulk volume, measurements were
conducted to find the volume of void space.
Several changes had been made in the flow-meter circuits,
such as amplifiers, buffers-and similar components, since the
first flow-meter calibrations were made. Also, the flow-meter
tests were run at elevated pressures. For these reasons,
calibration of the flow meters was made at atmospheric
29
-------
pressure, with the new components. Several 4000-ml.
calibration tests were made and the average of these readings
was calculated to evaluate the calibration coefficient. The
average was 806.45 ml./volt on the salt-water flow meter, which
was used for this test.
A low flow rate was desired for filling the reservoir from
the flow-meter system through the effluent lines around the
periphery of the reservoir, so as to eliminate air pockets.
The line to the effluent connection was filled before the valve
to the effluent lines was turned on. Because flow from the
effluent lines went to the high-permeability shell around the
reservoir core, the shell filled prior to any fluid's going
into the primary artificial rock. A long period of flowing
into the reservoir took place prior to our seeing any sign of
water in the 5 1/2-in. casing. When water did appear, it was
just as beads in a thin layer at the bottom of the artificial
reservoir. As time continued the flow coming into the
reservoir was monitored by looking inside casing and watching
the level of beads of water come out of the artificial rock.
This level was about halfway up the rock (about 1 ft.) before
the bottom of the casing began to fill. Beads were forming on
the surface of the rock and then running down the sides,
covering the entire surface up to the water level. This is an
indication of the amount of permeability.
About 2 hr. and 13 min. were required to fill the void
space in the housing to the lip on the hammer-union connection.
During this time total voltage of the salt-water flow meter was
measured as 102.355 volts. Because the flow meter is a
reciprocating type, the direction-change voltage level was
required; it was consistent at 9.69 volts at one end and 0.38
volts at the other end, as measured by a digital voltmeter.
Each cycle (or part of a cycle at the beginning and end of the
test) was summed to obtain the total voltage. Using the
calibration coefficient and converting the answer to gallons
resulted in 21.86 gal.
Some items in the reservoir housing were not in the
initial bulk-volume measurements; they must be accounted for.
These include gasket material, top and bottom; layers of RTV
adhesive sealer, top and bottom, the HDPE liner adjacent to the
wall, the high-permeability shell between the liner and the
reservoir rock, and of course, the reservoir rock. Porosity of
the high-permeability shell was assumed to be the same as was
measured by Amoco, 34.5 percent (Appendix B, Attachment B2).
Since dimensions of the solid components are known, then
individual volumes can be calculated. These are shown in
gallons:
30
-------
Volume of gasket material = 2(0.4877) gal.
Volume of RTV sealer = 2(0.2858) gal.
Volume of HOPE liner = 0.2152 gal.
Volume of shell = (1-0.345)*16.235 gal.
Volume of reservoir = (1-^))*80.04 gal.
It is noted that the reservoir volume did not include the hole
through the center, which is the same as the internal diameter
of the 5 1/2-in. casing. The common volumes are the inside
volume of the casing projected top to bottom, all the effluent
lines and fittings and the void spaces in the two rock
mixtures. A relationship is defined to determine the porosity
of the rock:
Initial Bulk Volume = Void Space + Displacement by Solids
The initial bulk volume was 104.20 ga.l. and the void-volume
that remained after placing the defined solids in the reservoir
housing was measured as 21.86 gal. By adding the volumes of
solids, the relationship becomes:
104.20 = 21.86 + 12.396 + (1 - <|>)*80.04
Solving this equation for 4> gives a value of 12.5 percent for
porosity. This was in the range of porosity that compares with
actual reservoirs.
PERMEABILITY TESTS
Once porosity is determined, then permeability tests can
be conducted. The supply line is changed from the peripheral
direction to the fitting just below the reservoir housing, so
that flow will be in the direction of flow that is potential
during salt-water-injection-tests. A value near 126 md. is
expected for this test, based upon the value of porosity (12.5
percent) and test results from Amoco (Figure B6).
During preparation for these tests it was found that
components in the data-acquisition system should be placed in a
dry env ironiaent. Several components were replaced and
considerable time was consumed in detecting problems. For
some sensors, voltage output from the sensor read with a
digital voltmeter and by the computer did not compare
favorably. Operational amplifiers were replaced to correct the
problem. Challenges such as this delayed progress.
Tubing fittings leaked at the 200-psi range and higher,
and although the leak was minute, it adversely affected the
sensitive differential-pressure transducer output. A new valve
31
-------
leaked, which also required devising an alternate procedure and
eventually the replacement of it. These are just a few of the
procedures that are typical with experimental projects; thus
delays follow.
Permeability tests were run with nominal pressure in the
artificial reservoir, about 400 psi, because of the calibration
characteristics of the differential-pressure and pressure
transducers. A set of expected values was calculated for the
test reservoir; at a radial differential pressure of 14 psi the
flow rate was expected to be 1397 ml./min. A source pressure
was adjusted to provide in excess of the 14 psi differential
pressure. The back-pressure by-pass valve was adjusted so that
it just was on the verge of opening at the nominal reservoir
pressure. Testing began with the drain valve open, which is
downstream of the back-pressure _valve, so the effluent could be
placed in a graduated cylinder to compare with the flow-meter
data. The pressure-source valve was opened and as pressure
increased the back-pressure by-pass valve opened and effluent
was caught in a bucket until count-down time. This was done in
order to direct flow into the cylinder for a period of a
minute; then flow was redirected into the bucket. During this
time the computer recorded data on flow rates, pressures and
differentials at nine locations, as well as date and time.
Time and selected pressures were also simultaneously recorded
by hand. After a period of flow the system was returned to a
static condition. This process was repeated several times.
Using the radial-flow equation, the test average results
and the measured dimensions of the artificial reservoir, a
value of permeability was calculated. Only a differential
pressure of 1.246 psi was measured for a flow rate of 1315
ml./min., which resulted in a -permeability value of 1257 md.
According to the porosity measured for this artificial
reservoir, the permeability was too great. At this point in
the cor.tract schedule, there is not time left to analyze fully
the reasons for the permeability results being so large.
During one of the many times of instrumentation and system
debugging, when the reservoir was brought to pressure, a
distinct "pop" or "crack" was heard. The present working
hypothesis is that bonding between the top of the reservoir
rock and the overlying gasket parted and that the parting
allows flow communication — an explanation of the high
permeability.
DRILLING-FLUID TESTS
Choosing a drilling fluid to test has a large latitude.
The requirements are at least 9.0 Ib./qal. mud with viscosity
32
-------
of 36 sec./qt. or more. There does not appear to be a
"typical" mud used for plugging. Our primary criteria were
that mud would meet the characteristics listed, that all
critical properties of the mud were measured in the laboratory,
and that the reaction with 8.7 Ib./gal. salt water would be
observed and documented.
It was decided that 70 bbl. of mud would be hauled from a
well-location, from which mud was being used currently to plug
wells. Weight of the mud was described as 9.0 Ib./gal. In the
initial tests, the mud weighed 8.99 Ib./gal. and viscosity was
34 sec./qt. While circulating mud through the mud-calibration
pipe section, back pressure changed erratically. Pressure
varied from about 300 psi to 800 psi; previously, when water
was run through the system, pressure was very steady. Cotton-
seed hulls were discovered in the mud; these periodically
plugged the back-pressure valve port and caused erratic
pressures. (In the future, to test with such additives in the
mud would be of value, but for the initial tests a deviation
from fresh mud of this magnitude would not be advisable.)
*
A full sequence of tests was not achieved, because of the
great amount of development time necessary to place into
operation a facility as complex as the one described here. Many
of the procedures involved were close to state-of-the-art. Of
positive importance is the fact that the system is at a point
in development where refinement will produce good results.
Also, several products that could be patentable were developed
during the course of this research.
33
-------
APPENDIX A
ASSOCIATED DRAWINGS AND DEVELOPMENT FOR THE
UPPER WELLBORE SIMULATION
Figure AI shows dimensions of the vessel that holds the
mud, and that is connected to the top of the artificial
reservoir.
A Temposonics transducer is placed in the top of the float
type flow meter shown in Figure A2. Details of parts of the
flow meter are shown in Figure A3.
34
-------
Mud Column - Simulated Wellbore Section
Bull
r -2- Swedgod
Slip-on T
8 Rnd. Thnj """
Casing Collar
;
Csng'
Sll(w>n T
8 Rnd. Thrd
Casing Collar
-7 Swedged Nipple
Line From
Flow Meter"
9' 6'
/
Figure Al. Simulated wellbore - mud column
above the reservoir zone.
35
-------
Mud Column Simulator
Flowmeter and Reservoir Assemblies
Flowmeter
.? 0««dg«d
r Casing
WL. »n. I.D.
17.00 6.538"
20.00 6.4 56"
22.00 6.398-
?100 6.366-
?4.00 6.336"
26.00 6.276-
28.00 6^14-
29.00 6.194-
Reservoir Tube
Figure A2. Mud-column flow-meter assembly.
36
-------
Mud Column Simulator
Flowmeter Parts
1/4- M«d Seel Plate
A 36 Of AISI 1030
Vtew-A-A'
DnllFor 1/2" Lng
12 Wood Screw
Figure A3. Detailed drawing of parts, mud-column flow meter
-------
APPENDIX B
DRAWINGS AND DEVELOPMENT ASSOCIATED WITH THE
ARTIFICIAL RESERVOIR
ROCK DEVELOPMENT, TESTING AND POURING PROCEDURE
DEVELOPMENT AND PLACEMENT OF THE ARTIFICIAL RESERVOIR
The artificial reservoi-r "was designed to simulate general
injection-zone conditions of rock type, porosity and
permeability. Sampling of shallow formations of sandstone in
areas near Oklahoma State University indicated that porosity in
the range of 15 percent to 20 percent, and permeability near
200 millidarcies would be close to the average properties of
injection zones.
In order to conform to petroleum-industry standards,
advice was sought from Halliburton Services, a company known to
have experimented with construction and treatment of artificial
reservoirs. Their valuable advice, cooperation and assistance
were given generously, as was the assistance of Amoco
Production Company, in the testing of samples of artificial
reservoir. Experimentation with composition and methods of
compaction of the artificial reservoir stemmed from suggestions
given by Mr. J. Murphey (see Attachment Bl of this appendix).
Principal components of the artificial reservoir are
very fine grained, clean quartz sand, coarse grained quartzose
sand (commonly used as a propping agent in fracturing of
formations), and a binder of resin (Figures Bl, B2).
Experimentation and construction of bench models initially were
modeled after the Standard Proctor Test, used extensively in
Civil Engineering to determine the moisture content at which
soil is at maximal density and maximal strength. Mixtures of
sand and resin were placed in a Proctor mold and compacted in
various measured amounts with a 5.5-lb. sliding hammer, dropped
consistently through a distance of approximately 11 in. (For
example, see Figure B3, and discussion of Sample 1, p. B2.2,
Attachment B2, this appendix.) Sand-and-resin mixtures
do not compact in the manner of soils, first being "fluffy,"
and then becoming "rubbery." From the outset, porosity and
permeability of the artificial reservoir were judged to be
strongly dependent on the extent and technique of "tamping."
.The first sample of reservoir was made according to
recommendations of Halliburton Services. Its appearance and
heft indicated strongly that the rock would have porosity and
38
-------
Figure Bl. Vials of very fine grained Oklahoma No. 1 quartz
Sand (left), and coarse grained, quartzose "12/20
mesh frac sand," the chief components of the
artificial reservoir.
39
-------
Reproduced from
best available copy
Figure B2. Disc of hardened resin the cementing agent in
the artificial reservoir.
40
-------
Figure B3. Standard Proctor mold (center), hammer (right),
and hydraulic-jack sample remover.
41
-------
permeability in amounts smaller than required for the overall
purposes of the experiment. (The correctness of this hypothesis
was demonstrated by tests conducted by Amoco (Attachment B2, p.
B2.2).) Numerous other samples were made, in general keeping
the proportions of sand as recommended by Halliburton, but
reducing the amounts of resin to fractions of the originally
recommended volume (Figure B4; Attachment B2).
A matter of additional concern was the outer "skin" shown
by several samples; at the interface of resin-and-sand and the
mold (coated on the inside with a waxy parting-agent), resin
formed a hard, lustrous surface, indicative of a layer of too
much cement, and strongly suggestive of a membrane of much less
permeability than the interior of the artificial rock. As
discussed elsewhere in this report, the design of the
artificial reservoir requires that fluid move radially through
the disc of rock and then to ports in the wall of the reservoir
housing. To test the hypothesis that resin-skin-effect could
be eliminated, and radial and peripheral movement of fluid at
the wall of the reservoir housing could be insured, a "shell"
of coarse grained sandstone was added in bench models of the
reservoir (Figure B5). The skin effect was eliminated; the
outer shell of the reservoir is rock of enormous permeability
(Attachment B2, Sample 8).
Overall results of the several samples tested by Amoco are
shown in Figure B6. Samples 5 and 6 are in the general range
of porosity and permeability expected in actual injection-
formations; these samples contained only about 80 percent of
the standard Halliburton recommendation, and both samples were
compacted in the Standard Proctor manner (Attachment B2).
Construction of the full-scale artificial reservoir was
modeled after the properties of Samples 5 and 6, Figure B6.
Amounts of sand and resin proportioned to yield a mixture of
approximately 80 percent of the full Halliburton recipe were
placed inside a coarse-grained shell, in several "lifts"
(Figures B7 through B9). The sand and resin necessarily were
mixed in batches in a mortar box, first by hand, then by use of
a small roto-tiller (with the better results). Each lift was
compacted by hand, with tools designed to have tamping-effects
similar to those of the Proctor hammer, and with technique
intended to duplicate the effects of the Proctor hammer,
insofar as possible.
SEALING OF RESERVOIR AT CONTACTS WITH BLIND FLANGES
Conditions of the experiment require that all fluid that
is injected into the reservoir flow generally in radial paths,
to discharge through ports in the side of the reservoir
42
-------
Figure B4. Molds 4 in. and 1 in. in diameter, and bench-test
samples of artificial reservoir. Samples were
poured to test methods of tamping the wet reservoir
mixture, to test porosity and permeability and
to test parting-compounds. Parting-compounds were
to insure that reservoir would not stick to housing
of artificial reservoir.
43
-------
Figure B5. A model of the artificial reservoir composed of
sand with resin binder. Light-colored portion
mostly is very fine grained quartzose sand.
Outer portion is coarse grained sand, with the
smaller proportion of resin. The outer "shell"
was designed to permit fluid to move freely at
the periphery of the reservoir, toward ports in
the wall of the artificial-reservoir housing.
44
-------
10000
C/)
•| 1000
ca
ra
0)
E
o>
Q.
100
10
Permeability (millidarcies)
vs.
Porosity (%)
,
! : : 1
.
1 I 1 1
' ' -L — !
/
/
/
DEI/
' y
1 / p 1 1
' ' ' '
|.78H|--
o6/
/
/SKI
/OS
/
/
/
/
till
1111
/
/
/
/
„ /
4/
LiilJo/
/
/
/
/
/
/
/
/
iiit
VEE:
CR£
RESE
(DATA: A(
1 1 l 1
1 1 ! !
i 14238
FICIAL
IRVOIR
wlOCO, INC.)
1 l l l
10 20
Porosity ( % ) •
30
Figure B6. Plot of porosity compared to permeability, samples
of artificial reservoir. Tests conducted by Amoco
Production Co. (See Attachment B2, Appendix B).
45
-------
Figure B7. Artificial-reservoir housing, showing view into
empty central chamber. Plywood disc supported
sheet-metal cylinder, which extended to within
1 in. of outer wall of reservoir housing. Within
this 1-in. space, coarse grained sand and resin
were poured to form highly permeable outer part
of reservoir.
46
-------
Figure B8. Interior of artificial-reservoir housing, during
emplacement of central part of reservoir. Average
size of grains in outer part of reservoir
suggested by loose grains atop housing-flange. A
"lift" of compacted fine grained sand with resin
binder partly fills reservoir housing. Coarse-
grained outer part of reservoir is separated from
metal of artificial-reservoir housing by a thick,
stiff high-density polyethylene liner, to which
the sand is not bonded.
47
-------
Figure B9. Nearly completed artificial reservoir. Several
"lifts" of fine grained material emplaced and
compacted within the hardened, coarse-grained
outer shell of reservoir.
48
-------
housing. Fluids are not to travel along the interfaces between
the top and bottom of the reservoir-disc and the blind flanges
of the reservoir housing (Figure BIO). Numerous tests were
conducted to find strong, sealing adhesive material that could
be placed on the top (and bottom) of the artificial reservoir,
under gasket material that would separate reservoir and blind
flange. Strength and flexibility are necessary properties of
the bonding material.
Adhesives tested were of three general types: acrylates,
epoxies, and silicones. Gasket materials tested were
polycarbonate plastics, mineral-based fiber materials, and
high-density polyethylene sheeting. Each adhesive was tested
for bonding-ability between the artificial reservoir and the
gasket materials (Figure Bll). Two adhesives were effective
to acceptable levels: Hardaan Acrylic-04050, and Permatex RTV
clear silicone; Hardman Acrylic-04050 is not available in
quantities required for this experiment. A second attribute of
Permatex RTV silicone was tested closely.: strength of bonding
to the Klinger C-4401 mineral-based fiber gasket material. A
knife-edge compression test (Figure B12) showed tha't
compressive force of 15,250 psi was required to separate the
adhesive and the gasket material; in a tensile-strength test,
(Figure B13) a load of 1,100 psi was required to separate the
adhesive from the gasket material and from the reservoir
material. All gasket materials were tested for compressive
strength; all withstood compressive loads of more than 15,000
psi without damage.
Permatex RTV clear Silicone Adhesive Sealer 66B was used
to form bond and seal between the artificial-reservoir material
and the Klinger C-4401 mineral-based fiber gasket material.
Because none of the ten adhesive substances tested would cling
to the high-density polyethylene sheeting (HDPE), this material
was used as the liner between the artificial reservoir and the
walls of the reservoir vessel (Figure B8), so that the
reservoir can be extracted.
ARTIFICIAL-RESERVOIR SYSTEM
Figure B14 shows the relationship of the artificial rock
to the reservoir housing and the wellhead assembly. Just the
housing is shown in Figure B15.
The radial location of the effluent lines is shown in
Figure B16 and the side view of these effluent lines is shown
in Figure B17.
49
-------
Figure BIO
Inner (lower) side of top blind flange of the
artificial-reservoir housing. The elevated
smooth surface between the outer ring of holes
and the central hole will be on top of the
artificial reservoir.
50
-------
Figure Bll. Tabs of polycarbonate gasket material attached to
sample of artificial reservoir, for testing the
strengths of bonding agents.
51
-------
Figure B12
Knife-edge compression test of sample of
artificial reservoir, on Versa-Tester
Model 1000 compression-testing device.
Test designed to measure splitting-
resistance of adhesive (not visible) that
binds two pieces of rock. The adhesive
was tested for effectiveness of bonding
artificial reservoir to gaskets between
reservoir and flanges of artificial-
reservoir housing. Compression of 15,250
psi was required to separate the materials.
52
-------
Figure B13
^'
• •
Specimens of artificial reservoir bonded to parts
of devices used in testing for tensile strength of
material. Adhesive was tested on a Riehle Test
Machine, for effectiveness of bonding artificial
reservoir to gaskets between reservoir and
flanges of artificial-reservoir housing.
53
-------
APPENDIX B
ATTACHMENT Bl
54
-------
CHEMICAL RESEARCH **.D
OEPT.
REGINALD M. LASATER. Managw
HONNEY R. KOCH. Assmla
HALUBURTON SERVICES
DRAWER 1431. DUNCAN. OKLAHOMA 73i36
May 8, 1989
Dr. Marvin Smith
499 Cordell, South
Oklahoma State University
Stillwattr, Ox 74078
Dear Dr. Smith:
As I mentioned on the phone in our conversation, the following
formulation using epoxy resins and fairly large sand should provide the 200
md "synthetic" formation you need. While this is not the formulation we
routinely use, it should be suitable for your application since no high
temperature cure is required. This limits usage of product to temperatures
below 120°F. At higher temperatures the epoxy resin will soften. The
final permeability is dependent upon the effort used in tamping the resin
coated sand down in to the mold. The resin coated sand will have the
texture of a stiff mortar before it hardens.
The following formation will mix about 2.3 cu. ft. It can be handled
in a small cement mixer:
1500 Okla. #1 S-and
5-i< 12/20 mesh frac sand
190 mixed eyoxy resin (mixed separately, then blended into the mixed
sands.)
Epoxy resin mixture (has a pot life of about 1 hour)
140 13 oz. of epoxy resin (ER-1)
67 cc. of Silane A-1120
Mix the above for about 5 minutes before continuing.
30 no oz. of epoxy hardener (EPSEAL C-4)
It 3 oz. of accelerator (EPSEAL C-l)
Avoid adding the accelerator until just before adding the resin mix to
the sand. Allow 3-5 minutes to completely mix the accelerator into the
other chemicals and then add the mixed resin to the sand.
C ' J A Hjllihuitoil Cuinp.jny
55
-------
Dr. Marvin Smith
May 8, 1989
page 2
Your test chamber sounds like it is about 13 cu. ft. As this is
probably too large an amount for a single batch, I want to stress that you
should tamp the coated sand in firmly, rough up the surface so that it will
blend in with the next batch and repeat the mixing procedure.
Clean the mixer at least every hour, using hot soapy water and a polar
organic solvent. Acetone, isopropyl alcohol, methyl ethyl ketone, methyl
chloroform are examples of material which may be used. The resin must be
removed from the mixer and all working tools before it hardens.
The following materials should provide for two tests.
20001 Okla II sand
6000 12/20 frac sand
20 gal (1821) ER-1 epoxy resin
•6 gal (40*) EPSEAL C-4
2 gal (13*) EPSEAL C-l
1 qt. (946 cc liquid) Silane A-1120)
I hope that these are satisfactory.
Sincerely,
Joe Murphey
Research Chemist
Water & Sand Control - CRO
JM:sc
cc: R. R. Koch
C. H. McDuff
J. A. Knox
J. M. Wilson
J. 0. Weaver
C. W. Smith
56
-------
APPENDIX B
ATTACHMENT B2
57
-------
AMOCO PRODUCTION COMPANY
LARGE CORE
CORE ANALYSIS DATA RECORD
LAB NO.I 2SB5801
DATE: 10-16-89
WELLi Oklahoma State Oniverait'* - Artiftcal Cores
FIELDi
STATEt
API WELL NO.:
Sample
NuoCer
1
2
3
4
5
6
Depch
lft|
...
...
...
...
...
...
Permeability-Mi 11 idarci en
Maximum
90" from Max.
Vertical
12.
2960.
257T1.
2890.
111.
324.
Porosity
»
6.7
20.1
19.4
20.5
12.9
14.1
Saturation
» - PV
Oil
H,0
Grain
Density
2.27
2.53
2.52
2.53
2.40
2.43
•Refer to attached OSU document < 89293ART0104 ) which describes
the make-up of each artificial core.
Description
•
•
•
•
•
•
-
SRD
58
-------
AMOCO PRODUCTION COMPANY
SMALL CORE
CORE ANALYSIS DATA RECORD
LAB NO.: 2585801
DATE: 10-18-89
WELL: O.S.U. - Arcifical Core Plugs
FIELD:
STATE:
API WELL NO.:
Sample
Number
7
8
Depch
(fc.)
— «.
_«
Permeability
Mj ti idarcies
Horiz.
7.8
=103,000
Vert.
Poro-
sity
«
17.0
34.5
Grain
Density
gWcc
2.39
2.57
Sat.
Z - PV
Oil
H20
Description
*
*
•Refer co attached OSU document (89293ART0104) which describes
the make-up of each artificial core.
-
SRD
a9291ART0050
59
-------
DESCRIPTION OF SAMPLES OF ARTIFICIAL ROCK, DELIVERED TO J. BOWEN, AMOCO,
BY M. SMITH, OKLA. STATE UNIV., 22 AUG. 89, P. 1/3
Sample 1: Dated 26 July 89 and labelled, in blue, "Full Halliburton Mix
With Standard Three-life Proctor Compact ion ."*"
1. Oklahoma No. 1 Sand: 1020.6 gm
2. "12 - 20" Frac sand: 340.2 gm
3. Epoxy Resin-1: 100.7 gm**
4. Epseal C-4 (hardener): 20.4 gm
5. Epseal C-l (accelerator): 8.1 gm
6. Si.lane: 1 cu cm
Silane was mixed with Epoxy Resin-1 for 5 minutes. To this mixture were
added Epseal C-4 and C-l. The composite fluid was mixed for 5 minutes,
then added to sand in small stream that was blended continuously by hand
mixing.
* The term "Standard Proctor Compaction" refers to the consolidation of •
soil in a mold that is 4 inches in diameter and 4.5 inches high, part of
a process to test soil for optimal density. In standard procedure the
mold is filled with three "lifts" of soil; each lift is compacted by the
dropping of a 5.5-pound hammer through 12 inches for 25 repetitions,
distributed "evenly" across the upper surface of the mold.
The mixture of sand and resin was compacted in a Proctor mold, by dropping
the 5.5-pound hammer through approximately 11 inches. (The mixture of
sand and resin was of a "fluffy" consistency, which allowed the hammer to
penetrate too far and which led to forcing of the mixture into the air-
discharge holes in the tubular hammer-guide.) Twenty-five blows were dis-
tributed "evenly" across each lift of sand-and-resin.
**A11 weights of fluids, as shown, are misleadingly exact. Measurement
could be controlled to 0.1 gm. However, actual amounts poured together
a;'.d ultimately mixed into sand were somewhat less than shown here,
because c.£ retention of fluid on sides and bottoms of containers. If
measurements of amounts retained are wanted, useful approximations of
the average amounts retained on vessels can be furnished.
Sample 2: Dated 28 July 89 and labelled: 3/4H, w/ Standard Proctor (Com-
pact ionTT
1. Oklahoma No. 1 Sand: 1020.6 gm
2. 12 - 20 Frac Sand: 340.2 gm
3. Epoxy Resin-1: 75.5 gm
A. Epseal C-4: 15.3 gm
5. Epseal C-l: 6.1 gm
6. Si.Lane: 0.8 cu cm
60
-------
Description, samples, artificial rock Co J. Bowen, AMOCO, from M. Smith,
QSU, 22 Aug. 89, p. 2/3
Note: Compacted in standard Proctor fashion, with final compaction of 25
blows onto rigid plastic disc atop sand-and-resin mixture.
Sample 3; Dated 31 JvAy 89 and labelled; "1/2H, w/ Full Proctor (Com-
pact
1.
2.
3.
4.
5.
6.
ion)."
Oklahoma No. 1 Sand:
"12 -20" frac Sand:
Epoxy Resin-1:
Epseal C-4:
Epseal C-l:
Silane: 0.5 cu cm
1020.6 gm
340.2 gm
50.4 gm
10.2 gm
4.0 gm
Five compacted lifts were required to produce a full mold. Compaction
seemed to be effective for a few blows, after which the material developed
a rather resilient toughness. Topmost lift was compacted evenly across
the surface, but last impact left a "footprint." The final compaction was
done by puccir.g a rigid plastic disc atop the sand-and-resin mix, and ham-
mering the disc 25 evenly spaced blows.
Sample 4; Dated 8-3-89 and labelled; "Modified Proctor, 1/2 (Hallibur-
ton) Mix."
1.
2.
3.
4.
5.
6.
Oklahoma No. 1 Sand:
12 - 20 Frac Sand:
Epoxy Resin-1:
Epseal. C-4:
Epseal C-l:
Silane: 0.5 cu cm
1020.6 gm
340.2 gm
50.4 gm
10.2 gm
4.0 gm
Compaction: With Proctor hammer, to "rubbery" consistency.
Sample 5; Dated 16 Aug. 89 and labelled; "80+."
Sample mixed using standard amounts of sand, but content of resin only
about 80 percent of amount shown in listing under Sample 1. Standard
Proctor compaction.
61
-------
Description, samples, artificial rock, to J. Bowen, from M. Smith, OSU,
22 Aug. 89, p. 3/3.
Sample 6; Dated 16 August 89 and labelled; "78Z".
Sample mixed using standard amounts of sand, but concent of resin only
0.78 of amount shown in listing under Sample 1. Standard Proctor com-
paction.
Sample 7: 1 inch in diameter and labelled: "ER"
Molded sample with amount of.sand proportional to Halliburton specifica-
tions, but 75 percent of Halliburton specifications for resin. Compacted
by hand, moderately. One end of sample had full mixture of resin
"floated" onto surface.
Sample 8: 1 inch in diameter and labelled: "12/20."
Molded sample of 12 - 20 frac sand only, with 75 percent of standard Hal-
liburton resin. Compacted by hand, moderately.
SRDrsdg
89293ART0104
62
-------
I) ARTIFICIAL
IU RESERVOIR
Figure B14. Shaded area shows placement of the artificial
reservoir rock.
63
-------
RESERVOIR SPOOLPIECE
VIEWO-C
SPOOLPIECE MTL: 36" O.D. X .750 WALL
API 5LX-X65HT .383
2440 p.s.i. Test Pressure
Figure B15. Artificial-reservoir housing with modified blind-
flange end pieces.
64
-------
Figures B18 through B25 are details of the wellhead
assembly, and connection with the housing assembly, and the
reservoir-housing support stand.
65
-------
A
a-
B
16 !/»•
c
24 !M'
0
ai s/16-
E
40 iTJ-
F
«« 1/2-
G
56 WIT
NOTE. TV£ LOWER RING OF RESERVOIR LEAKOFF HOLES
ARE OFFSET BY APPROXIMATELY 26" FROM THE TOP RING.
Figure B16. Locations of reservoir-housing effluent lines
66
-------
Tubing Layout On
Spoolpiece Section
Figure B17. Configuration of reservoir-housing effluent lines,
67
-------
Figure B18. Water connections, mud connections, and well-head
configuration below the artificial reservoir.
63
-------
Qs-s.., G)
Figure B19. Artificial-reservoir-housing support stand,
69
-------
Figure B20. Adjusting-jacks for artificial-reservoir stand,
Note; SK#7 is a
flat steel plate,
10 1/2 in. in diameter
and 1/2 in. thick.
Other numbers with
prefix SK are in
Figures B20 through B24.
70
-------
HORIZONTAL SUPPORTS
1
28
i Ml"
2 1/4-
. 1
21M-R
24"
^w**"" """^v
**' , S*\
¥• . 4
4 2 IM-
*
PART #2
QTY-4
1
1
1
11 ' X
NT^
^ ,/^N
T
1/2-
PART »1
QTY=4
2 IM' H —/ ' | 2 1/4- H —/
Figure B21. Details of supports for reservoir stand.
REV.
CSO \l-l\-al
71
-------
SECTION "C-C"
Figure B22. Details of cross-member configuration for
reservoir stand.
72
-------
SKETCH "4": CORNER GUSSETS
MATL- 1/4'THICK, A-36 PIT. STEEL (A.I.S.I. 1010)
QTY. - 16. (SHEAR OR BURN)
BREAK EDGE AND
GRIND SURFACE SMOOTH
.5'.
Figure B23. Gusset details for artificial-reservoir housing
stand.
73
-------
SKETCH #3: PIPE LAYOUT
INSTRUCTIONS: Layout (2), *5* angles from a drawn canter ol the tubing, and Him as shown. On the opposna
end repeal the operation so thai the apeiec ol Ihe 4S's are on the same axial cenierlme.
C/L
Trim end oft alter
making 45* cuts
Figure B24. Details of dimensions to cut pipe for welding.
74
-------
ASSEMBLY STAND
FOR ARTIFICIAL RESERVOIR
MOTtS:
' ALL TUBING SHALL BE 4 1/2" CASING
* ALL WELDS SHALL BE MINIMUM OF 1/4' FILLETS
OALL HOLES AS ROD FOA
LAC BCLTS
1/4" t 11- OIA.
~A- I* fLATC tTKEI
Figure B25. Assembly stand for artificial-reservoir
housing.
75
-------
APPENDIX C
I
SIMULATED LOWER WELLBORE DRAWINGS
Figure Cl-A shows how the wellhead slips had to be cut
away in a sector to provide a conduit for the instrument lead
lines and the salt-water line. An adapter was made for the
salt- water line so that the 1/2-in. and 1/4-in. tubing passes
through the head and is connected to the 1 1/4-in. tubing below
the slips. Figure Cl-B shows a detail of this adapter.
A detailed arrangement of the casing and tubing string and
the mounting of instruments is shown in Figure C2.
Figures C3 and C4 show how casing was arranged by size to
accommodate the series of tests at different depths.
76
-------
11 7/8"
5 1/2" Csng.
1/2" S.S. Tubing
Supply Line
1/4" Bleed Line
i
I
Tubing Adaptor
1 1/4" Injection
Tubing
Figure Cl-A. Well-head configuration of tubing and casing,
77
-------
Inject Bleed
1/2" S.S. Tubing
Injection Line
Silver Solder
Weld-,
1-1/4"NUE
SawHill Tubing
I
\
X.
i J2
t\
t\
t\
',\
',\
'\
'\
'<\
;\
j\
?\
j\
\
\
\
\
i
-
'////////////
yy////
s^a
'
/
jowy
$
\
\
\
&
1/4" S.S. Tubing
Bleed Line
2"
Tubing Adaptor
Figure Cl-B. Tubing adapter, salt-water injection system,
78
-------
<£>
Casing String Instrumentation
Location Chart For EPA Test #1
1 1/4' Dia.
Sail Water
Injection Tubing
x^j _5 i/2' Casing 1 1/«- s«n w«w mi^on Tutanj
i
j
j
4
1
J
4'
ie2 er
i7t er
t 53'
l
i
1
i
62- |
t
32 It
6«'
f
-T-
3t er
i
i
4;
i
20
4*
181 ;
oo' i :
^=, :
A '" •
6* *
4 1
- 1
' 30'
. 30'
u
= :•* a
•20' J
: ; 1 3'
{_.,....,,_ Locflftm rl (flPT PT PSH ft Tf) ,'
8' f<-
\" ' * ' '
4
\* P
^p
^
n i
i
~J
1/4" lr*»trum*m*l!on Tubing tr
j
'
3'6
' 1
el'
X
_l
i
2 1
f-
93' -31-
31
1 1
21'
*
T
•21'
|
rj'
n
t
— Location rt i
33
Jni
^ ,._._.
61
I
33 67'
Jni
jr""
f
'
27'
Jnt.
L_
T
A
« s«-
»
A
5 6*'
f
A
3'
1_
i
V V«tv»
Aii*mbl)r
K
3/4' St»»J Plilt
Figure C2. Location of tubing and instruments, Test No. 1.
-------
Jm»3
33.W
Jni. «1
33.9T
39.35'
147
40 26
• 46
47 SI
• 37
47 5«
• 35
36 61
• 45
Casing & Tubing
String Layouts
For EPA Tests
JM >
32.74'
Jnt «
U.49-
Jnl no
33.9?
jm •«
33.91'
u
40.68
•42
•47 57
•44
41.50'
• 52
39.08
• 51
39 97
• 43
30 13
• 49
40.80'
• 48
Jm •!!
33.19'
Jit «13
33 .!•'
39 15'
•33
40.93'
O4
34 13
• 3«
41 43
• 38
41 '
• 39
41 57
• 40
40 80'
• 4 I
Page #1
Figure C3. Location of joints of casing by number and
dimensions as they are placed in 10 3/4-in,
casing.
80
-------
Casing & Tubing
String Layouts
For EPA Tests
1S'Pl4> Jit
jnt ra
32.7V
Jnl«22
11.U'
Jnl m
13. W
14.73'
L
Jni n\ 1
•a u- -*-
jrx. #70
13 «•
41.>0
• 27
40.63
•28
40.94
•28
41 or
•30
17.021
•31
4i «r
•32
Jnt *2I
12.11-
jnt f27
H»r
jnt nt
31 12-
40.11
•22
42.il
• 21
4200
• 24
19 90
• 25
41 02
• 26
19 15
• 14
40.64
115
.itto.r miK-Kxt Oo>«
19.15
• 17
19 II
• 16
4005
• 19
42 12
• 20
Figure C4. Continuation of Figure C3.
Page »2
81
-------
APPENDIX D
DRAWINGS AND DEVELOPMENT OF INSTRUMENTATION
DIAPHRAGM HOUSING
The diaphragm-seal housing shown in Figure Dl serves as an
interface between fresh-water mud in 5 1/2-in. casing and
distilled water in the tubing connected to the pressure and
differential-pressure transducers. Accuracy of data collected
from the pressure and differential-pressure transducers is
dependent on maintaining this interface. The following is a
discussion of problems and solutions associated with sealing
the diaphragm-seal housing.
The diaphragm has a flange-type configuration with a 180-
deg. convolution. Calculated torque, based on a 15-percent
compression of th.e gasket portion of the diaphragm, was
approximately 25 in-lb.
A test diaphragm-seal housing was assembled by welding a
diaphragm housing to a short section of 5 1/2-in. casing
approximately 3 ft. long.
A test pressure of 3000 psi is required. It was assumed
that when the diaphragm was put in place, the housing
assembled, and the flange bolts torqued to 25 in-lb. that a
water-tight seal at 3000 psi would result. However, the seal
leaked at approximately 800 psi.
The diaphragm was checked for flaws or tears, etc. None
were detected. The diaphragm housing was also inspected for
possible flaws, machine marks, foreign particles, but none were
detected.
The diaphragm-seal housing was reassembled and
hydrostatically tested under the conditions described above.
Again, the seal leaked at approximately 800 psi.
Torque on the flange bolts was increased by increments of
10 in-lb. to a maximum of 55 in-lb. Each condition resulted in
a leak at the seal. A no-leak maximum of 1000 psi was
obtained.
A series of gasket material, sealing compounds, adhesives,
and combinations thereof was attempted with minimal success.
Results are tabulated in Table Dl.
82
-------
-l!
U-"
,
1
:;j ij;-j
B—1 -\
,„ .
4
ur
t
+ !V
t
1M-
i
^
jiff-
^
Section 'B-B*
Diaphragm Housing-
( Diaphragm Installed)
Figure Dl. Detail of the diaphragm housing for interface
between mud and water.
83
-------
TABLE Dl. DIAPHRAGM-SEAL TEST RESULTS
Description 1
of Seal F]
i
Red Rubber
Gasket Material
Black Rubber
Fabric Gasket
(1/32 inch)
Black Rubber
Fabric Gasket
(1/16 inch)
Diaphram with
Loctite Master
Gasket
Diaphram with
Loctite Ultra Blue
Diaphram with
J.B. Weld
Diaphram with
Loctite Fast Cure
Epoxy 45
torque or
Lange Bo]
(in-lbs.)
25
35
45
55
25
35
45
55
25
35
45
55
25
55
25
55
25
55
25
55
60
60
i Seal Lea]
Its Pressure
i (psi)
400
450
450
450
800
900
1200
1250
825
1000
1100
1150
600
650
450
500
1500
1850
2200
2800
3200
3000
C
Comments
gask. extruding
it it
due to torque
due to pressure
due to pressure
M it
II M
due to pressure
ii it
due to pressure
ii ii
very small leak
n M
very small leak
n n
n M
no leak
84
-------
Loctite Fast Cure Epoxy 45 proved to be reliable for the
3000 psi test pressure and was adopted for use for Operating
Procedure 3.0.3.
It was later determined that due to flexing of the 5 1/2-
in. casing, the seal of the diaphragm seal-housing was good
only to 2000 psi. No pressures greater than 2000 psi were
expected for the first test. Therefore the assembly procedure
was maintained, at least for the first test.
Consideration of a new design of the diaphragm seal
housing is suggested for subsequent tests.
PRESSURE AND DIFFERENTIAL-PRESSURE TRANSDUCERS
Figures D2 and D3 show configuration of the connections
for specific locations in the test system. The six down-hole
locations shown in Figure C2 are related to configurations in
Figure D3. Note that the bottom location (No. 1)-does not have
a transducer. It is the bottom leg of the differential-
pressure transducer in Location 2. Location 2 is at the salt-
water injection point.
DESIGN OF PISTON-TYPE FLOW METER
A piston assembly with inner and outer seals rides on
stainless steel tubing inside of cylinder (Figure D4). A
magnet is shown in the left-hand part of the figure; this is
the element that the Temposonics transducer senses, to find
position in the piston. A detailed view is shown in Figure D5.
The inter-relationship of the Temposonics transducer and
the piston is shown in Figure D6. The effective travel is
indicated.
Figure D7 shows the complete assembly of the flow meter.
Flow comes in either end cap and exits at the opposite end
cap, depending on the specific direction of flow. The position
of the magnet with respect to time is translated to flow rate.
85
-------
Artificial Reservoir Layout For Epa Test
Location #7
(Artificial Reservoir)
co
CTv
Mounting location
Is onirio O.O.
of the Anidcial Reservoir
Diaphragm Seal
Housing
Diaphragm Seal Housing
Is located on (he S 1/2' Csng
6* below the Artificial Reservoir
Diaphragm Seal
Housing
Figure D2. Configuration of above-ground pressure transducers,
-------
Location #1
Location #2
Diaphragm Seal
Housing
•33
To 0*l«r
-------
Flow Meter Piston
Assembly Drawing
Trgooa Tuoing
Figure D4. Flow-meter piston assembly,
88
-------
Flow Meter Piston
Flow Meter Piston Assembly Drawing
\
Figure D5. Magnet/piston assembly for the effluent and- salt-
water flow meters.
89
-------
LINEAR DISPLACEMENT TRANSDUCER ASSEMBLY
FOR
FLOWMETER
b,
'
PLUS ADDITIONAL
r LENGTH FOR CY1..
END CAP
»u
__ -[?
«r STROKE WTTHr ADDITIONAL
-LENGTH FOR ELECTRONIC SCALE
AND NULL AOJUSTKCNT
»U
1n/_
J/T (INSERTED IMTO
CYLENDCAP)
FLUSH END
STYLE 02-SRH (SMALL RUGGEDIZED HEAD) NEMA 4 RATING
NEVW 4 RATING. WATER-TIGHT. OUST-TIGHT. INDOOR AND OUTDOOR
PROTECTED AGAINST SPLASHING. FALLING. AND HOSE-DIRECTED
WATER)
Figure D6.
Temposonics linear-displacement transducer and
magnet/piston for the effluent and salt-water
flow meters.
90
-------
FLOWMETER ASSEMBLY
7TKF5 >~: C
STTLI c; - s RE ;
cfl
5 ||-
«
<|-
•-i id*
\>
1
¥
•X^\S
-••
W^
». i/it-
F
llllllll ,-.=!
TT*
m
NNN^
ii>
«,
60 I/I
>*-i »/»
j / \ L-
^i, j 3, |»- »
W
^SMiS.
vW'WvJS-'s
Uw
J^»»
'{
-
!
r-^X l /
/ \ A . . . \ /
J
^
V,»iCSn TWJ-fcC O-RIK BCCj
(£D 3TTiU -C- PC;
. rucv DTD
Ic4.1 l*-JS TT?OO« luklifl OPTIO. 01
* TJOXItlXCOl
•CO
r i icitM
481" Dl* fd 0004
rrtn TUBIIC
Figure D7. Flow-meter assembly for the effluent and salt-water
systems.
-------
APPENDIX E
INSTRUMENT CALIBRATION
PRESSURE TRANSDUCERS AND DIFFERENTIAL-PRESSURE TRANSDUCERS
Time and equipment were donated by Conoco, Inc. in Ponca
City. A pressure-measurement system was taken to Conoco's
facility and their DH 5501 deadweight-pressure-tester
system was used. This is a highly sensitive and accurate
system. Calibration could not have been done without the
cooperation of Conoco.
All of pre-sized cables, the computer and software,
multiplexer, pressure transducers and differential-pressure
transducers were taken to the site. Before calibration, these
were assembled in the configurations that they would have in
the test system. Because of the time required to balance the
system for each pressure, because of the multiple line
pressures, and because of the sensitivity of the diaphragms,
calibration was long and tedious. Conoco supplied an operator
and a supervisor, but our own personnel assembled the systems
to be calibrated and operated the two computers.
In Figure El the DH 5501 is seen in the left-hand portion
of the photograph. Instruments, multiplexers, data-acquisition
system and computer are elsewhere in the photograph. The data-
reduction computer system Is shown in Figure E2.
A closer view of the required system is shown in Figure
E3. The long lengths of wire are to connect sensors to the
multiplexer in the down-hole configuration; the long wire was
used to take into account any line-losses. Each transducer was
connected to the appropriate position on the appropriate
multiplexer, and the output was seen on the digital voltmeter
and on the computer screen. All steps were taken that are
required in the actual test-configuration. Data were stored on
floppy disks; these were used in the data-reduction computer.
In order to keep from damaging the differential-pressure
transducers a special flow network was designed and built. It
is shown in Figure E4.
Results of this calibration procedure are in Table El.
FLOW METER CALIBRATION
Three flow meters are mounted on the Instrumentation
Console (Figure E5). These three act separately in normal
92
-------
Reproduced from
best available copy.
Figure El. Overview of pressure- and differential-pressure
calibration process at Conoco, Inc.
93
-------
Figure E2. Computer system used in the overall
calibration process at Conoco, Inc.
94
-------
Figure E3. Instrument lead-lines, transducers, multiplexer and
digital voltmeter used in pressure- and differential-
pressure-transducer calibration process at Conoco,
Inc.
95
-------
Figure E4. Differential-pressure transducer pressure-
equalization network for calibration at
Conoco, Inc.
96
-------
Table El. Calibrated Pressure Transducers
TRANSDUCER
NUMBER
PT032-25.CAL
PT038-30.CAL
PT136-10.CAL
PT137-10.CAL
PT138-30.CAL
DP033-05.CAL
DP033-15.CAL
DP033-25.CAL
DP034-15.CAL
DP034-25.CAL
DP035-05.CAL
DP035-15.CAL
DP035-25.CAL
DP036-05.CAL
DP036-15.CAL
• DP036-25.CAL
DP037-05.CAL
DP037-15.CAL
DP037-25.CAL
DP139-04.CAL
DP139-10.CAL
DP139-15.CAL
DP140-04.CAL
DP140-10.CAL
DP140-15.CAL
DP141-04.CAL
DP141-10.CAL
DP141-15.CAL
DP142-04.CAL
DP142-10.CAL
DP142-15.CAL
CAL.
ORDER
Second
Third
Second
Third
Third
Third
Third
Third -
Third
Third
Second
Third
Third
Third
Second
Third
Third
Second
Third
Third
Third
Third
Third
Second
Second
Third
Third
Third
Third
Third
Second
INTERCEPT
-15.0078
-817.835
-255.822
-257.688
-809.03
0.018025
0.180946
0.235349
-0.00219
-0.01134
-0.03383
-0.01577
-0.00181
-0.00083
0.057773
0.001588
-0.3012
-0.46079
-1.14542
-0.03286
-0.02798
-0.01029
-0.26747
-0.40609
-0.45502
-3.76935
0.005253
1.174866
-7.47667
-3.53824
-1.88412
X
641.583
858.0032
264.2174
266.8794
837.715
0.958496
0.927259
0.808925
1.665724
1.783586
2.531405
2.564948
2.584269
4.5565
4.082549
4.479852
4.193761
4.069449
4.638432
0.270412
0.254886
0.263378
10.2276
10.145
10.30998
53.49224
52.74301
50.38612
204.8533
202.6816
202.8089
COEFFICIEN1
1.350509
-21.0604
-2.03393
-2.56352
-16.9311
0.016785
0.024139
0.003119
-0.02616
-0.196
-0.00869
-0.02263
-0.03398
-0.18622
0.01175
-0.15147
-0.11797
-0.02235
-0.39268
-0.0016
-0.00143
-0.01732
-0.07129
-0.01623
-0.03587
-3.20371
-1.0668
-0.00372
-3.57379
-0.9419
-0.44082
TS
NA
0.90863
NA
0.061186
0.619525
-0.00219
-0.00358
0.000333
0.002819
0.031635
NA
0.001539
0.002761
0.018681
NA
0.014939
0.017907
NA
0.058048
0.000353
0.000388
0.002552
0.006628
NA
NA
0.52476
0.101462
-0.02136
0.563824
0.09615
NA
97
-------
operation but during calibration are connected. The flow meter
that is for the mud column is connected to the Vindum valve
going into the salt-water injection flow meter; from the output
of the salt-water flow meter this is connected to the input to
the reservoir-fluid flow meter. During calibration, the mud-
column flow meter is filled with water and nitrogen pressure is
imposed on this flow meter. Thus pressure and fluid are
supplied in order to drive flow through the salt-water-
injection flow meter. Fluid then moves to the reservoir-
effluent flow meter; then the effluent goes into a vessel that
is on a scale (Figure E5). The scale allows readings to a
tenth of a gram. Output of this scale is fed to a computer
(Figure E6) so that the digital data are recorded on the hard
disk.
Each of the three flow meters has a Temposonics linear
transducer that records the position of a magnet. The position
of this magnet is measured precisely to 0.001 in.; with this
the amount of flow that has gone from the flow meter to its
destination can be determined. The conditioned electrical
output of the Temposonics is fed through a multiplexer to the
computer and stored on a hard disk. Because there are three of
these Temposonics, the multiplexer will rotate the signals and
record them serially.
Three pressure transducers also are mounted on the flow-
meter network, as seen in Figure E7; these are mounted near the
Vindum valves. The 1000-psi pressure transducer mounted on the
downstream side of the salt-water-injection flow meter measures
the pressure developed during operation of the flow meter. Two
pressure transducers are mounted on either side of the Vindum
valves on the reservoir-effluent flow meter. This allows
determination of a pressure differential across the Vindum
valves, during operation. Included in the console is a 1000-
psi pressure gauge on the reservoir-effluent side, and a 1500-
psi pressure gauge is on the salt-water side. All other
outputs to the computer go to the multiplexer, so that the
serial output is obtained; this cycles through at a rate of
about 10 per second.
Before calibration starts, each of the flow meters must be
prepared for operation. The reservoir-effluent flow meter and
the salt-water-injection flow meter require that fluid be
placed on both sides of the piston, which contains a magnet.
Doing this requires that air be bled from the lines. In order
to prepare the mud-column flow meter a hose must be connected
to the vessel and filled with water. Once this is filled,
nitrogen pressure (Figure E8) must be turned on and regulated
to the particular pressure that will be used during
calibration. Various ranges of pressures will be measured, so
98
-------
Figure E5. Overview of flow-meter calibration system with
computer, scales and Instrumentation Console.
99
-------
Figure E6-. Computer, multiplexer for surface sensors, power
supply and leads for calibrating flow meters on
Instrumentation Console.
100
-------
Figure E7. Front side of Instrumentation Console, with
three flow meters.
101
-------
Figure E8. Back side of Instrumentation Console, with
three flow meters.
102
-------
that more than one calibration will be done for the flow
meters.
It should be noted that calibration must end temporarily
when the mud-column flow-meter vessel is emptied. Therefore,
the amount of flow must be monitored and exposed during the
process. In order to restart the process, nitrogen pressure
must be blown down and the vessel refilled with water and
pressurized with nitrogen.
The components of these three flow meters are divided into
sections on the console, with some overlap. Basically, the
mud-column flow meter is in the right-hand section of the
console. Figures E9 and E10 are focused on these components.
On the left-hand side is the effluent flow meter; some of its
components are shown in Figure Ell. Figure E12 is focused upon
some of the components associated with the salt-water-injection
flow meter; it is in the central section of the console.
The following definitions are used:
VI = Vindum valve No. 1, which is the top control valve in
the reservoir-effluent flow meter network.
V2 = Vindum valve No. 2, which is the control valve in the
reservoir-effluent flow meter network.
V3 = Vindum valve No. 3, which is the top control valve in the
salt-water flow meter network.
V4 = Vindum valve No. 4, which is the bottom control valve in
the salt-water flow meter network.
PT = Pressure transducer.
BPV = Back-pressure valve.
CALIBRATION PROCEDURE FOR SIMULTANEOUS FLOW METER OPERATION
Note: Must have system bled prior to calibrating.
^
I. Set BPV pressure.
1. Close all ports to VI and V2 and close BPV (turn
clockwise to increase pressure).
2. Charge the 1-gal. accumulator with nitrogen to the
desired back pressure.
3. Turn BPV counterclockwise (decrease) until effluent
just begins to seep out of the line.
II. Initialize the flow.
1. Open all ports to Vindum valves VI, V2, V3, and V4.
2. Increase nitrogen pressure to mud-column flow meter
until pressures equal back pressure.
3. Allow total system to equilibrate.
4. Set Vindum valves VI, V2, V2, and V4 to their
operating modes.
5. Slowly increase nitrogen pressure until there is
103
-------
Lgure E9. Electronics, flow-line connections and controls
for mud-column flow meter.
104
-------
Figure E10. Simulated wellbore - mud column. Flow
meter in right-hand side of photograph,
105
-------
Figure Ell. Electronics, flow lines, controls and line
configuration for calibration of effluent
flow meter.
106
-------
Figure E12. Electronics, flow lines with configuration
for calibration of salt-water flow meter.
107
-------
visible flow from reservoir-effluent line. This initial
flow should be as slow as can be controlled — just a
drip or seep.
III. Record data.
1. Set computer to cycle through all activated sensors.
2. Manually record both gauge pressure and the scale
output,as well as date arid time. Do this periodically
throughout the run.
3. Allow enough time for pistons in flow meters to span
their complete range of travel
4. Allow enough time for the system to equilibrate before
going to next flow rate.
IV. Span the flow range.
1. Increase pressure until flow increases to rate desired.
2. Proceed with Steps 3.1, 3.2, and 3.3.
3. Repeat steps 4.1 and 4.2 until entire flow range has
been spanned.
V. Span back-pressure range.
1. Do steps r-IV for each back pressure desired.
2. Choose back pressures coincident with test schedule.
108
-------
APPENDIX F
DEVELOPMENT OF TEST FACILITY - OVERVIEW
INTRODUCTION
Several items were originated with development of this
project. These developments are discussed in the following
paragraphs.
ACCURATE DOWN-HOLE PRESSURE-GRADIENT MEASUREMENTS
Both a technique and hardware were developed to accurately
measure down-hole pressure gradients. First a special
technique to determine differential pressure with a combination
of manometer principles, differential-pressure transducers and
pressure transducers was developed. This technique requires
simultaneous solutions of data from these three sources.
Also, a multiplexer was designed and built to transfer
data from down-hole to the surface. This takes signals from
each of a set of instruments, processes the information, and
serially transfers it to a computer. A computer board was
designed and built to accept and process data at the computer
interface.
In addition, a' data-acquisition software system was
developed to interface with the multiplexers, sort the serial
data, and store it.
A diaphragm-seal housing assembly was designed and built
to interface between mud in the casing and water in the
instrument lines, to provide accuracy and prevent plugging.
A temperature-sensor circuit was designed and built to
enhance the accuracy of temperature measurements.
SIMULATED RESERVOIR ROCK, FLOW AND PRESSURE CHARACTERISTICS
Several techniques were developed to simulate the
significant conditions that occur in a reservoir while
pressures are being imposed upon it, comprised of reservoir-
fluid and mud-column pressure enhanced by injection pressures.
Associated with these techniques are several devices of
hardware that were designed and constructed, including a
cylindrical reservoir housing'with blind flanges, for placement
and removal of the artificial-reservoir material.
Instrumentation and fluid-flow ports were included in the
109
-------
design and fabrication. Artificial-reservoir material was
developed to yield a desired set of permeability values, based
upon guidelines from Halliburton Services Company. This
artificial reservoir has permeability barriers on the top and
bottom of the format.ion to promote uniform radial flow between
the ends, but to not allow flow around the ends. A high-
permeability shell on the outer cylindrical surface provides
vertical flow paths, to maintain uniform radial flow through
the reservoir.
A flow-meter and flow-control system was designed, built
and developed to accurately measure very low flow rates at
high pressure and to maintain a constant back pressure, which
simulates virgin reservoir encroachment. Also, an injection-
pressure system and flow-meter system was designed, built and
developed, to provide the ability to measure very low flow
rates at high pressure and to control the system at various
constant injection-pressure levels. A third flow meter was
designed, built, and developed. This is a mud-column pressure
control and flow meter used to maintain a constant head of
pressure on the mud column. This will simulate various depths
and measure any flow that occurs going down-hole. It also acts
as a solid plug when injection pressures control the flow
potential.
A mud-mixing, mud-flow network and control system, to
operate in conjunction with the mud-column flow meter system
was designed and built, so that mud cake could be formed on the
wellbore of the artificial reservoir.
We also designed and constructed a well system which
provides a means of simulating conditions below the artificial
reservoir to depths as great as 2000 ft. This system also is a
means of controlled injection of fluids at any depth from 100
ft. to 2000 ft. This well system will provide the potential
to investigate many phenomena, but some conditions can not be
simulated accurately and the dynamic effects of a long mud
column is one case.
DEVELOPMENT OF SUBSURFACE FACILITIES
Jr.'s Rat Hole Drilling Company drilled a 60-in.-diameter
rat hole 4 ft. deep. Because of wet weather, a bulldozer was
used to pull the rig off location. Both a mud reserve pit and a
working mud pit were dug. Grace Drilling was delayed from
rigging up due to inclement weather, and when they begani to
drill they were hindered by mud-pump problems. They drilled to
333 ft. and then A-3 Casing crew set the casing and Dowell-
Schlumberger cemented it. Drilling resumed for the 10 3/4-in.
casing and total depth of 2110 ft. was reached four days
110
-------
later. Gearhart Inc. logged the well and then A-3 Casing crew
set the casing and Dowel1-Schlumberger cemented it bottom to
top. Only the coupling on the 10 3/4-in. casing can be seen,
near the edge of the concrete pad in the central foreground of
Figure Fl.
DEVELOPMENT OF FACILITIES AT THE SURFACE
After the well was completed the concrete pad was formed,
steel placed, tied and concrete was poured. This pad was
designed to withstand the weight of the forklift, plus the
artificial-reservoir housing and the artificial reservoir
filled with water. It is 40 ft. by 30 ft.; it is shown in the
central region of Figure Fl. The size is based on the turning
radius of the f oriel if t and the equipment required to be placed
on it.
The instrumentation building is the checkered building on
the left side of Figure Fl. A four-line plastic tubing ground
loop was trenched and laid with an automated Ditch Witch
machine. Use of the equipment was donated by Ditch Witch'. This
ground loop is coupled to a water-source heat pump in the
instrumentation building, to supply proper temperatures for the
computer and data acquisition system. The heat pump was also
donated.
An electrical load requirement was designed for the
facility. Trenches were dug, conduits placed in the trenches,
wires were pulled and circuits were completed. Water and gas
lines were laid prior to the electrical lines, because of the
depth requirements.
A cinder pad was made for the 'tank battery and rock/gravel
was put in the drive and parking area. Rock was also placed on
the dirt road leading to the test site. The foreground in
Figure Fl shows the parking area, and in the right-hand side is
the tank-battery cinder pad.
Figure F2 shows the salt-water tank, pump and plumbing in
the foreground. This facility is used for salt-water injection
into the well. In the background is the tank that receives
effluent from all the flow activities. These fluids are held in
the tank for proper disposal.
The mud system is shown in Figure F3. The view is
northeastward. Pipe racks are to the south of the mud system.
The pipe network in the foreground is configured to allow
bypass back to the tank under a given pressure, flow through
the artificial reservoir, circulation through the calibration
lines or just circulation back to the tank. The mud pump is
111
-------
-
Figure Fl. Mud-plug facility; view northeastward
112
-------
Figure F2. Salt-water tank in foreground; effluent tank behind,
113
-------
Figure F3. Mud pump, pipe network, tank and mixer system.
114
-------
near the center .of the figure, with a flex-hose discharge and a
pulsation dampener, as well as a pressure-relief valve. Near
the tank and on the right side is the calibration system,
consisting of lines, control valves, sample container and
scales for weighing the mud. Above the mud tank is the motor
and drive for the mud-mixing impeller. The shaft is between
the mud-mixer frame and the pulsation dampener. This system
supplies mud to fill the wellbore and mud circulation to build
a mud cake in the reservoir.
Figure F4 shows the v-door, attached to the pipe rack. On
the pipe rack is the 5 1/2-in. casing for the simulated
wellbore, the 1 1/4-in. tubing for injection of salt water, and
2 3/8-in. tubing for filling and jetting the well.
In Figure F5 the simulated wellbore-mud column section is
lain on the pad prior to placing it on the tubing above the
artificial reservoir. The artificial reservoir is shown in the
environmental control building, as it would be placed while
testing (Figure F6). The wellbore-mud column is inserted
through the roof and attached to the tubing oh top of the
artificial reservoir.
A part of the mud-column system is shown on the top of the
artificial reservoir in Figure F7. This figure primarily is
the artificial-reservoir housing assembly. The mid-section is
the 36-in. pipe with an array of flow lines for the effluent
from the reservoir. The flange and blind-flange pairs on the
top and bottom are for reservoir-rock placement and removal.
On the left side of the housing is a pressure transducer and a
line going to the differential-pressure transducer, on the
casing sub on top of the housing. A pressure transducer and
two differential-pressure transducers are mounted on the casing
above the top blind flange. The mud-inlet connection is under
the housing, and sticking out to the left at an angle to the
bottom casing sub. The artificial-reservoir housing is on the
assembly stand. This is the location where the unit was
hydrostatically pressure-tested and where the artificial-
reservoir material is placed in the housing. Also, this is
where the porosity and overall permeability of the rock are to
'be measured.
Figure F8 shows a closer view of the effluent lines from
the reservoir housing, which are to come .to a common point to
discharge to the effluent tank. Also, the diaphragm-seal
housing is placed to keep the instrument fluid separated from
the effluent mud, but still to measure the pressure. The cross
above it has one leg going to the pressure transducer, one to
the pressure gauge, one from the diaphragm, and the vertical
one extends to the radial differential-pressure transducer.
115
-------
Figure F4. V-door attached to pipe rack; casing and turbine.
116
-------
Figure F5. Simulated well-bore and mud-column section,
117
-------
Figure F6. Artificial-reservoir system in environment-control
building.
118
-------
Figure F7. Artificial-reservoir housing assembly.
119
-------
Figure F8. Peripheral effluent lines and instruments on
artificial-reservoir housing.
120
-------
In Figure F9 the centralizer is at the far end of the
casing. This keeps the instruments protected while the casing
is lowered in the hole. The end with the centralizer goes into
the borehole first. Above the centralizer is where the first
differential-pressure lead line, diaphragm and temperature
sensor are located. Closer to the viewer's position is the
location of the differential-pressure transducer, which
connects the two diaphragm housings shown in the figure. The
pressure transducer, temperature sensor and salt-water
injection port are at the same nominal location. Figure F10 is
a view up-hole from the salt-water injection port; it shows the
salt-water injection tubing and the instrument wire and tubing,
which extend to the next sensor.
The pulling unit is in the background of Figure Fll, in
position to run tubing and casing. Behind it are the well-head
and the artificial-reservoir test stand. The reservoir is
moved to this location after mud lias been pumped into the 5
1/2-in. instrumented casing. On the left side is the end of
the v-door. It is bolted to the pipe rack and the end section
is removed after pipe has been run.
In Figure Fll the view is southward, whereas the view in
Figure F12 is westward. In Figure F12 the well-head
configuration is that of tubing in the hole ready to be used to
run mud to the bottom. Wire sticking out of the casing head
is composed of lead lines from the down-hole instruments.
These will be connected to the multiplexer, shown in Figure F13
and then to the computer in the instrumentation building, shown
in Figure F14.
The heart of the measuring system at the surface is shown
in Figure E5. It is the flow-meter and pressure-control
system, which is referred to as the instrumentation console.
With it the observer will know whether mud cake is protecting
the reservoir zone.
121
-------
Figure F9. First (lowermost) joint of casing, with
instrumentation.
122
-------
Reproduced from
best available copy
Figure F10. Bottom end of first (lowermost) joint of casing,
as seen in the up-hole direction.
123
-------
Figure Fll. Pulling unit and well site,
124
-------
i
Figure F12. Well configuration for placement of water
and mud in 5 1/2-in. casing, through
2 3/8-in. tubing.
125
-------
Figure F13. Multiplexer mounted on casing.
126
-------
Figure F14. Heat pump and computer inside instrumentation
building.
127
-------
APPENDIX G
QUALITY ASSURANCE PLAN
PROJECT OBJECTIVES, DATA USE, AND ACCEPTANCE CRITERIA
Current methods of plugging abandoned wells use drilling
mud as a plugging agent. A major question concerns the
performance of the plugging agent when injection wells are
activated in the vicinity of the plugged wells. Thus, the
primary objective of the proposed research is to test this
hypothesis: Drilling mud in abandoned, properly plugged wells
effectively seals the borehole. However, if fluids injected
into reservoirs at depth -were to migrate up the boreholes of
such abandoned wells, filter cake nevertheless would prevent
passage of these fluids into other reservoirs. The alternate
hypotheses need no elaboration. A secondary objective is to
obtain fundamental information on conditions of mud in the
simulated well in order to provide guidelines for developing a
technique and an associated instrumentation system to enter
abandoned wells. These abandoned wells would be ones that
were recorded as having been plugged properly. Entering these
wells to obtain fundamental information about the condition of
the borehole and the mud column would require specialized
techniques and an instrumentation system to minimize altering
downhole conditions and to provide proper interpretation of
results.
One of the primary objectives of the project can be
restated using performance variables. Results of the test
will include values of low rates induced by particular
injection pressures, along with other variables, as shown in
Table Gl. A plot of flow rate versus injection pressure, with
other variables held constant, will generate a family of
curves. This family of curves will define an envelope of
performance characteristics. The envelope will show the
combination of variables that potentially produces invasion of
the reservoir — or conversely, it will show the combination
of variables under which the reservoir effectively would
remain sealed. Thus, the results of the test will indicate
the effectiveness of drilling mud as a -plugging agent in
accordance with a specific range of well conditions.
Mud properties as a function of time and depth are to be
determined within a borehole, to establish characteristics of
the mud as a plugging agent. Differential-pressure transducers
will be placed on the casing to measure pressure gradients
within the casing from above the simulated reservoir to the
bottom of the casing. Similarly, temperature sensors will be
128
-------
Table Gl. Array of test .variables for tests 1 through 6.
CONTROLLED VARIABLE
TEST NUMBER
RESERVOIR DEPTH (FT)
MUD COLUMN PRESSURE
AT RES. DEPTH (PSI)
RESERVOIR PRES.(PSI)
INJECTION DEPTH (FT)
MUD COLUMN PRESSURE
AT INJ. DEPTH (PSI)
1
1000
468
450
1168
547
INJECTION PRES.(PSI) 557
to
INJ. FRAC. PRES. 880
** (MAX. ALLOWABLE 1497
RESERVOIR PROPERTIES
PERMEABILITY (MD)
POROSITY (%)
FLUID PROPERTIES
MUD WEIGHT (LB/GAL)
.SALT H20 WT. (LB/GAL)
100
21
9.0
8.7
2
1000
468
450
1500
702
712
to
1200
1684
100
21
9.0
8.7
3
1000
468
450
2000
936
946
to
1600
1918
100
21
9.0
8.7
4
1000
468
450
2000
936
946
to
1600
1918
150
21
9.0
8.7
5
2000
936
900
3000
1404
1414
to
2400
1918
150
21
9.0
8.7
6
2000
936
900
4000
1872
1882
to
3200
2386)
150
21
9.0
8.7
LEACHING
A minimum for all tests in the series.
** NOTE: 1450 PSI IS THE MAXIMUM WORKING PRESSURE THAT THE
RESERVOIR COKTAINER WILL HOLD. IF FRACTURE PRESSURE
EXCEEDS THE MAXIMUM ALLOWABLE THEN THE TEST IS LIMITED
BY:
MAX. ALLOWABLE PRESSURE = MUD COL. PRES. AT INJ. DEPTH
+ ( 1450 PSI - MUD COL. PRES. AT RESER. DEPTH )
129
-------
placed on the casing. If the density of the fluid that caps
the total column of 'mud is known, then the average density
between sensor-locations throughout the column of mud can be
determined from the pressure and temperature gradients.
Coupling these data with the mud properties and constituents
(known from measurements made on the mud prior to circulation
of it into the casing), the mixture of constituents at various
depths can be calculated. Duplicates of these will be
formulated at the surface and placed into aging-cells, to
measure the shear properties at the time when injection into
the well bore (casing) begins. Gel strength will also be
measured with these samples. The shear stresses and gel
strengths will be used to indicate the resistance to flow, and
will be correlated with injection pressures required to invade
a given reservoir. Other data will be obtained from the mud
(prior to circulating it into the casing) such as Marsh Funnnel
viscosity, plastic viscosity, apparent viscosity, yield point,
shear strength, fluid loss, density, pH, and resistivity. This
information will be used to correlate field data with results
of experients.
A set of pressure-time history curves will be obtained for
the period of time beginning with circulation of mud into the
well and ending with stabilization of pressures in the static
mud column. These pressures and their associated gradients
will be used to estimate the change in potential for formation
fluids to invade the well. Also, pressure-time histories
during the period when fluid is injected into a lower formation
will be recorded. Analysis of this information will allow
estimates of the plugging capability of the mud under the
controlled conditions.
The simulated reservoir will be evaluated for specific
properties. These attributes will be correlated with field
data to determine what field conditions would lead to invasion.
These properties are porosity, permeability, reservoir
pressure, and wellbore pressure. In addition, the amount and
rate of fluid invasion into the reservoir will be mapped, along
with a pattern of invasion. These data will also be used to
correlate experimental data with field data to show potential
invasion problems.
Flow rates of mud will be measured while circulating the
mud through the simulated reservoir. Injection flow rates,
cumulative flow, temperature and pressure will be measured
during injection periods. Injection-fluid density and
viscosity for each type of fluid will also be measured. All of
these measured values will be included in the correlations of
field conditions with experimental data.
130
-------
Values from each of the variables measured will be
reviewed for application in directing the development of a
technique to insert tools into an abandoned, plugged well and
measure the significant variables with minimal interference and
error. Structural configuration, strength and sensitivity are
some of the tool-attributes that would be sought.
To test the major working hypothesis, it is necessary to
detect that second-stage invasion (i.e., invasion due to
breaching of previously established mud cake) did or did not
occur through the artificial reservoir. Moreover, it is
necessary to know what the associated values of critical
variables (discussed earlier) are, within a narrow error-band.
The width of the error-band should be as small as that which
the standard instrument can measure reliably for each variable.
These same criteria will satisfy the secondary objective of the
proposed research project.
DATA-QUALITY OBJECTIVES
Successful detection of whether fluid enters the simulated
wellbore during the injection period is essential to success
of the project. Because fluid could enter at a rate too small
for many of the standard flowmeters to detect accurately, or
could come in at a very large rate, the design of a unique
flowmeter is required to resolve both extreme situations. An
error of 0.00017 barrel-per-day is sufficient in the low range
(0.02 barrel-per-day); a 0.015 barrel-per-day in the higher
range (15 barrel-per-day).
Pressure measurements are to confirm the flow data and
assist in determining local properties of the mud. Pressure
transducers with accuracy of plus or minus 1 percent of the
full scale will be used. Full scale is 3000 psi. Also, an
array of differential-pressure guages in the simulated
reservoir area and at the bottom of 100 feet of casing will be
used, to obtain greater sensitivity.
Temperature within the fluid system must be monitored and
measured to assist in defining local properties of the mud and
to assist in detecting fluid migration. Temperature sensors
with accuracy of plus or minus 1 percent of full scale are
readily available. Obtaining temperature within 0.5 to 1.0
degrees Fahrenheit will provide acceptable results.
SELECTION OF SAMPLING LOCATIONS AND COLLECTION OF SAMPLES
The 2000-ft. casing that simulates a wellbore will be
sampled for pressure at 100-ft. intervals, in general. However,
at the bottom of the casing, pressures and differential
131
-------
pressures will be sampled at locations according to Figure C2.
Temperature will be sampled at 300-ft. intervals except near
the injection depth. At this position temperature will be
sampled according to Figure C2.
Sampling of data from the simulated reservoir will come
from locations at 16 positions on the periphery of the
artificial-reservoir housing. Data will also be taken just
above and below the 2-ft.-thick reservoir.
Cores of the simulated reservoir will be collected for
laboratory analysis. Upon disassembly of the reservoir mold
and inspection of the reservoir material, cores will be
collected from it. These will be placed in containers, marked
and stored in the analytical laboratory prior to evaluation.
Mud will be mixed according to the results of evaluating
temperature-and-pressure data from the test well. These
specific mixtures will be place in aging-cells, which will be
marked according to depth and date. The aging-cells will be
placed in an oven at the appropriate temperature, to age until
injection in the well commences. At that time shear tests will
be run on the samples of mud.
HANDLING, IDENTIFICATION AND STORAGE OF SAMPLES
Core samples from the simulated reservoirs will be
collected. Each sample will be placed in a container and
identified. The core will be marked with a date and index
number. In addition, the container will be marked with the
date and number. A data sheet showing the same date and number
will also identify the location (radius, depth and azimuth)
with respect to the simulated reservoir, the test number, test
duration, simulated depth of core and injection point, mud
pressure at the simulated reservoir, injection pressure, and
type of injection fluid.
Data will be stored on computer disks and in bound
notebooks. Core samples will be stored in the School of
Geology.
METHODS OF MEASUREMENT, AND PERFORMANCE CHARACTERISTICS
For the most part, methods of measurement are considered
to be standard. Data collection from temperature sensors,
pressure sensors, and from flowmeters will be accomplished by a
data-acquisition system developed by the Oklahoma State
University Electronics Research and Development Laboratory.
This method employs a down-hole remote-multiplexing scheme for
selection of the sensor to be monitored. An interface card
132
-------
that plugs into an IBM PC-XT or compatible computer is used to
address a multiplexer input, convert the analog data to digital
data, and store the data on a disk, with other applicable
information. System software is developed, using Microsoft
"C".
An encoder on the interface board is controlled by the
computer to select and hold the sensor addressed, until a value
from the sensor is read. The binary address is encoded into a
Bi-phase Level Pulse Code Modulated (PCM) signal that is
transmitted by shielded twisted-pair wire to the remote
multiplexer decoder. The decoder identifies the address and
opens the corresponding multiplexer channel of the selected
sensor. The output of the multiplexer containing the selected
sensor voltage value is conditioned and fed to a voltage-to-
current converter. The output of the converter is a O-to-20
milliampere current loop that is sent up-hole through a
shielded twisted-pair wire to the computer interface board.
This current is converted to a precision voltage and fed into a
12-bit analog-to-digital converter. This digitized value is
read by the computer, added to any applicable calibration
offset, converted to an engineering unit (e.g., degrees
Centigrade), and stored in memory. At midnight of each day,
the data will be stored on disk with day and date, time, sensor
number, and sensor value. Normally, data well be sampled at
all sensors at 10-minute intervals.
A remote-multiplexing scheme was chosen because of the
limited space for wiring in the borehole. Instead of a
twisted-pair wire coming from each sensor, only three pairs of
wires will extend upward from each multiplexer box. These
wires will be for the address-data, returning-sensor-value, and
for power. Sixteen to twenty-four inputs will be fed into each
remote multiplexer. Data-loss will be minimized by this
process: The computer will reboot^automatically after a power
failure, and will automatically resume the recording of data.
The test facility, as designed, has the capability to
provide an array of independently controlled variables. These
variables are listed below, with explanation of how they will
differ and the ranges of expected values.
Injection Depth
The 5 1/2-in. casing has multiple perforations in the
central portion of the bottom joint. As the casing is set in
the well by hanging from the slips in the well head, the
adjustment can be made so that the depth below the simulated
reservoir is from 100 ft. to 2000 ft. Initial tests will begin
at the 100-ft. depth and increase to the 2000-ft. depth below
133
-------
the reservoir by addition of casing joints to the string.
Depths of 100, 500, 1000, 1500 and 2000 ft. below the simulated
reservoir are planned, but the time required to run the test
will dictate the number of depths that can be simulated. These
depths are to be added to the simulated depth of the artificial
reservoir.
Depth of Artificial Reservoir (Invaded Formation)
A column of mud in a 5 1/2-in. casing protruding above the
artificial reservoir will be pressurized with a cylinder and a
high-pressure nitrogen bottle, to achieve the pressure at the
artificial reservoir commensurate with the mud in the well.
This series of tests will be run only at the Oklahoma
Corporation Coauniss ion's designated plugging mud weight of 9
Ibs./gallon. Therefore, the »ud weight is 0.468 psi/ft. or at
a depth of 1000 ft., the pressure 'would be 468 psi. To
simulate depth, a pressure would be applied at the artificial
reservoir to be commensurate with the mud column at that depth.
Depths of the invaded reservoir will range from 400 ft. to 3000.
ft. Thus, the maximal simulated depth for injection will be
5000 ft.
Artificial-reservoir Pressure (Invaded Zone)
A large accumulator will accept effluent from the
artificial reservoir and the pressure in the accumulator
bladder will be maintained at the designated reservoir pressure
with a high-pressure nitrogen bottle and both a regulating
valve and a relief valve (see Figure 3). The fluid coming
from the well bore to the reservoir would be working against a
constant reservoir pressure. Reservoirs at different depths
have different fluid-pressures, ranging from about 0.433
psi/ft. to about 0.471 psi/ft. of depth. In the case at hand,
the chosen pressure-range, will be from 0.433 psi/ft. to 0.45
psi/ft. Initial tests will begin at 0.45 psi/ft. and reduce to
0.44 psi/ft. and then 0.433 psi/ft., depending on available
time. A new mud cake must be developed each time the reservoir
pressure is changed because the change in pressure between the
well pressure and the reservoir pressure would increase,
thereby increasing the driving potential. This would result in
deeper invasion of the mud into the reservoir.
Injection Pressure
Another bladder-type accumulator will be used to supply
the fluid to be injected into the well bore full of mud. A
high pressure nitrogen bottle will supply pressure to the
bladder, which will force the injection fluid to the well bore.
A tight-band-pressure control valve will meter the nitrogen
134
-------
into the bladder to maintain correct pressure. Pressures will
range from 10 psi above the well pressure at the injection
depth to a maximum of 0.8 psi/ft multiplied by the injection
depth (unless significant invasion of the reservoir took place
at a lower pressure). With all other variables remaining
constant the injection pressure will be increased and time will
be allowed for a reaction to occur. If nothing detectable
happens, then the pressure will be increased and the process
repeated until the reservoir is invaded or the maximum pressure
(based on 0.8 psi/ft or 1450 psi at the simulated reservoir) is
obtained.
Reservoir Properties
A review of some Oklahoma formations that potentially
would be invaded from the wellbore due to injection above or
below the zone revealed a porosity range from about 18 percent
to 24 percent. Initial tests will begin with about 21 percent
porosity and depending on time available, the 18 and 24 percent
runs will be made. Tentatively, permeabilities for these
reservoirs will be in the range of 50 to 150 millidarcies. The
initial reservoir will have permeability of about 100
millidarcies unless subsequent information supports a different
value. Again, time will dictate the number of permeability
cases which will be run.
Fluid Properties
The tvo fluids involved in the initial test series are the
9.0 pound/gal mud and salt water. Mud in the simulated well is
going to be placed at the one consistency for this test
program. Salt water with a specific gravity that yields about
8.7 pound/gal would be the initial injection fluid. if time
permits a 9.0 and a 9.3 pound/gal salt water would be tested.
The salt water of least density is expected to have the
greatest potential for invading a zone above the injection
zone.
Leaching
Movement of water out of mud in the well bore occurs if
mud cake is not sufficient to effect a complete plug. Leaking
would occur until a balance among the well-bore pressure, the
reservoir pressure and the resistance to flow (mud cake) is
achieved. It is anticipated that no substantial leaking will
take place during the period between when the mud cake is
formed and when injection commences for the current test
program. Effluent will be detected. In the future,to create a
situation that would cause substantial leaking to occur and to
test for integrity under these conditions would be informative.
135
-------
Test Sequence
A maximum of six different simulated reservoirs is
scheduled for this contract. This is tentative because the
time to reach an equilibrium to simulate an abandoned plugged
well is not known, and time limitations on the contract would
dictate the number of tests. Measurements of mud-pressure
gradients in the lower joints of casing will provide data to
determine equilibrium conditions. Table Gl shows the test
schedule.
Standards for Measuring Mud and Reservoir Properties
A list of operating procedures is contained in Appendix H,
and embedded in these are various standards. Examples of these
are listed below.
Mud Standards API RP 13B (Second Edition)
STANDARD PROCEDURE FOR LABORATORY
TESTING DRILLING FLUIDS
API RP 131 (Eleventh Edition)
STANDARD PROCEDURE FOR FIELD TESTING
DRILLING FLUIDS
Reservoir API RP 27 (Third Edition)
RECOMMENDED PRACTICE FOR DETERMINING
PERMEABILITY OF POROUS MEDIA
API RP 40 (First Edition)
RECOMMENDED PRACTICE FOR CORE-ANALYSIS
PROCEDURE
QUALITY CONTROL AND QUALITY ASSURANCE
Quality control and quality assurance are accomplished
through the implementation of logical guidelines and operation
procedures. In this document a series of steps to achieve the
test-objectives is outlined. These steps are supported with
specific operating procedures that are listed in Appendix H.
Integrated into these procedures are the sampling methods, ways
of storage and preparation of samples, and methods of analysis.
Also included are measurement techniques, quality-control
measures and methods of working with the data. Methods of
minimizing down-time and ways to recover data if parts of the
system fail are included in the specific procedures.
136
-------
DATA REDUCTION AND REPORTING
Field and laboratory data will be recorded on floppy disks
and on forms that itemize each variable required, the data, and
the assigned test-number. A "Comment" section will be provided
for the recording of pertinent information. The hand-written
documents will be completed in a periodic manner until an
extraordinary event is detected; then a higher frequency of
data-procurement could be desirable. The forms will be
amenable to entry of data into the computer. Most of the data
will be recorded electronically and continuously, with the
data-collecting system, and will be stored on disks. With all
this information, a data-base will be established to provide
easy access for data-reduction programs.
Multivariate linear regression analysis will be used to
determine significant statistical parameters. Nonlinear
regression analysis will be applied to models to determine
empirical correlation equations.
Data will be reported in tabular form and in graphical
form, to enhance clarity of results. Preliminary data will be
supplied in quarterly reports; data will be shown in
completeness in the final report.
Characteristics of Computer Data System
Most of the data will be processed directly into the
computer and saved on the hard disk, and then a "back-up"
floppy disk copy will be made. Periodic printouts will be made
to allow review of the data in progress. A range of expected
values for the variables will be used to compare with the
computer output, to determine the validity of data. The
pressure and temperature data will be processed down-hole and
sent out as electrical current. A digital format and
conversion to engineering units will be achieved at the
surface. Hardware and software for these signals will be
designed and built by personnel of Oklahoma State University
who do this type of work for the Space Program's remote
sensing. Each sensor will be calibrated while on the surface
and the calibration curve programmed in the processor and
digitized. A dead-weight tester will be the standard for •
pressure calibration and a precision thermometer and
environmental chamber will provide the means of calibrating the
temperature sensors. A calibration check will be made prior to
each time fresh mud is put into the well. This will be done by
flushing water through the well after displacing the old mud
and having clean water in the well. Knowing the temperature
and density of the water in the well and knowing the locations
of the sensors, the pressures and temperatures can be computed
137
-------
and compared to the sensor outputs displayed on the computer
screen or on a printout.
Software will be generated by faculty and staff at
Oklahoma State University and it will be verified by using
known inputs and comparing tire output with hand-calculated or
known results. Data-reduction software will be a combination of
commercial software and that generated locally. Regression
analysis will be accomplished using a commercial software
package. The files to be read by the software for the
regression analysis will be generated by our own software.
An empirical model will be developed using variables
listed in Table Gl as injection depth, reservoir depth,
injection pressure, reservoir pressure and permeability. These
are independent variables with the dependent variable being the
effluent flow rate from the simulated reservoir. Regression
coefficients will be determined from the array of data and the
regression-analysis program. An output of .the program will
list the estimated statistical parameters. Also provided will
be an asymptotic correlation matrix of the parameters.
Uncertainties in Measured Values
Uncertainties or errors in the measured values will vary
with each calibration curve and instrument. A list of the
major values measured showing expected errors is shown in the
following table.
VARIABLE MAXIMUM READING ERROR (+/~)
Pressure difference 10 psi 0.05 psi
Pressure 3000 psi 30 psi
Temperature 90 deg.C . 0.3 deg.C
Flow rate - mud 44 gpm 1 gpm
Flow rate - salt water 5 gpm 0.5 gpm
Flow rate - inj. fluid
& effluent 25 gph 0.0005 gph
Flow rate - mud column 115 gph 0.0002 gph
138
-------
STRUCTURE OF THE GENERAL EXPERIMENT: STEPS WITHIN ONE
CYCLE OF INJECTION
Figure Gl indicates the steps that can be done in
parallel with others and those that must be done serially.
1. Build artificial reservoir of sand and epoxy. (See
Operating Procedure (O. P. 1) .
2. Calibrate instruments according to Operating Procedure 2.
3. At pipe rack, mount instruments on casing, according to
design of test. (For example, see Figure C2, which shows
design of casing instrumentation for Test 1.) (Also see
0. P. 3) .
4. Build casing string with pulling unit and run string into
borehole, according to Operational Procedure 4.
5. First cycle of reservoir-testing only: Fill 5 1/2-in.
casing string with water to clean out, and to
double-check calibrations of instruments. (See 0. P. 5).
6. Measure porosity and permeability of reservoir on Assembly
Stand (Figure 2, Location A) by filling artificial
reservoir with salt water and flowing water through
reservoir. (0. P. 6).
7. Make artificial reservoir ready for placement over
borehole, according to Operational Procedure 7.
8. Homogenize drilling mud. Place mud in 5 1/2-in. casing
using tubing set to bottom of hole. Check instruments by
measuring and recording gradient-effects of mud. (See
Operational Procedures 8.1 through 8.4, and 5.3).
9. . Place reservoir over borehole (Figure 2, Location B) and
make all connections for flow-lines, instrumentation and
back-pressure controls. (0. P. 9) .
10. At Location B (Figure 2), build mud cake in reservoir
section: To retain salt water in reservoir, make up hammer
couple. Deflate packer. Displace packer out top with mud.
Circulate mud through well bore in reservoir. When flow
of mud filtrate radially through reservoir stops, then mud
cake is built. Bring primary mud flow to zero, while
maintaining well-bore pressure at simulated depth,
according to Table 1. (See Operating Procedure 10).
139-
-------
Generalized Sequence Of Events
Post-test
Evaluation
Phase
Test Preparation Phase
Data-evaluation
Phase
Figure Gl. Sequence of events during one cycle of injection
tests.
-------
11. Let mud sit in column until equilibrium is reached, as
measured by stabilization of temperature and pressure
gradients across sensors. Monitor for displacement of
fluid from column above reservoir, for detection of
leakage in casing or migration through mud cake. (See
Operating Procedure 11).
12. When mud equilibrates, begin injection of salt water at 10
psi above mud-column pressure, at injection point.
Maintain for period of time judged to be sufficient for
effect at reservoir. If flow from reservoir is
undetectable, then increase injection pressure by
increment specified in Operating Procedure 12.3. However,
if flow from reservoir is detectable but less than 25 gpm,
then increase pressure by the amount described in
Operating Procedure 12.4. These steps would be repeated
until (a) flow rate is equal to or greater than 25 gpm, or
(b) the maximal injection pressure has been achieved.
13. Dismount artificial reservoir housing and move housing
from Location B to Location A (Figure 2). (Operating
Procedure 13).
14. Collect samples from reservoir according to sampling
scheme prescribed for physical description of reservoir
(Operating Procedure 14). Label and store as prescribed,
in preparation for analysis.
15. Evacuate drilling mud in casing by water-displacement.
Test calibration of down-hole sensors. Evacuate water
with air, then swab dry. (0. P. 15).
16. Plot injection pressure against observed flow rates at
reservoir-exit. Analyze these data to describe
preservation or loss of reservoir integrity under
experimental conditions. (0. P. 16).
17. Petura to step 1.
141
-------
APPENDIX H
OPERATING PROCEDURES: SUMMARY LISTING
1. Construction of artificial reservoir.
1.1 Preparation of artificial-reservoir housing to
receive sand mixture.
1.2 Preparation of sand mixture.
1.3 Filling of housing with sand mixture.
1.4 Emplacement of top flange, artificial-reservoir
housing.
2. Primary calibration of instruments.
2.1 Calibration of pressure gauges.
2.2 Calibration of pressure and differential-pressure
transducers.
2.3 Calibration of temperature-sensors.
2.4 Calibration of flow meters.
2.5 Calibration of mud-flow-rate system.
2.6 Calibration of salt-water turbine meter.
3. Mounting of instruments.
3.0 Mounting diaphragm-seal housings.
3.1 Mounting of differential-pressure transducers.
3,2 Mounting of pressure transducers.
3.3 Mounting of temperature sensors.
3.4 Mounting of multiplexers.
3.5 Placing of flow meters.
3.6 Mounting of pressure gauges.
4. Running instrumented casing string into borehole.
142
-------
4.0 Pipe selection.
4.1 Positioning casing joint.
4.2 Connecting instrumentation lead-lines.
4.3 Mechanical installation of first joint.
4.4 Mechanical installation of second and all other
joints.
4.5 Recording instrumentation position and location on
casing string.
4.6 Securing top joint and lead-lines in wellhead.
Calibration-check of down-hole sensors and data-
acquisition system.
5.1 Emplacement of water in casing string for calibration
check, of down-hole sensors.
5.2 Activation and check-out of computerized data-
acquisition system.
5.3 Initial calibration-check of sensors.
Measurement of overall porosity and permeability.
6.1 Measuring porosity of artificial reservoir within
housing.
6.2 Measuring permeability of artificial reservoir within
housing.
Preparation of artificial reservoir for movement to
position above borehole.
7.1 Containment of fluid within artificial reservoir
during removal of instruments.
7.2 Installation of reservoir pick-up assembly.
Preparation of drilling mud, emplacement in casing and
removal from casing string.
8.1 Mixing of mud according to Oklahoma Corporation
Commission's standards for well-plugging.
8.2 Homogenization of drilling mud.
143
-------
8.3 Sampling and testing of drilling mud.
8.4 Emplacement of drilling mud in casing string. (O.P.
11.1).
8.5 Removal of drilling mud from casing string. (O.P.
15.1)
9. Connection of artificial reservoir to casing string.
9.1 Placement of reservoir stand.
9.2 Placement of artificial reservoir on reservoir stand.
10. Building of mud cake.
10.1 Homogenization of drilling mud (O.P. 8.2).
10.2 Displacement of packer.
10.3 Adjustment of flow rate and back-pressure.
10.4 Monitoring of mud-filtrate flow rate.
10.5 Sampling and testing of drilling mud (O.P. 8.3).
10.6 Shut-down procedure and line removal.
10.7 Refined adjustment of pressure to prescribed
magnitude.
11. Monitoring for equilibration of mud in casing string.
11.1 Monitoring of mud column (exposed to atmosphere)
immediately after emplacement, for differential
pressure, pressure and temperature.
11.2 Monitoring of mud column at simulated-depth
conditions for differential pressure, pressure and
temperature.
12. Monitoring effects of salt-water injection.
12.1 Activation of salt-water injection system.
12.2 Monitoring and recording comprehensive pressure
differentials, pressures and flow rates.
12.3 Increasing injection pressure in response to
undetectable flow from reservoir.
144
-------
12.4 Increasing injection pressure in response to low
rates of flow from reservoir.
12.5 Termination of injection in response to maximized
flow or pressure.
13. Transfer of artificial-reservoir housing from test
stand to assembly stand.
13.1 Removal of instrumentation from artificial-rreservoir
housing.
13.2 Disconnecting reservoir housing from casing string.
13.3 Installation of reservoir pick-up assembly and
movement of reservoir housing.
14. Sampling of artificial reservoir.
14.1 Removal of artificial reservoir from housing.
14.2 Mapping and labeling of reservoir surface for random
sampling.
14.3 Collection of random samples: channel samples,
stratified samples and spot samples.
14.4 Labeling and storage of samples.
15. Evacuation of liquids from casing string.
15.1 Displacing drilling mud with water.
15.2 Calibration check of sensors (O.P. 5.3).
15.3 Displacing water with air.
15.4 Shut-down of computerized data-acquisition system.
16. Analysis of data and reporting of conclusions.
16.1 Documentation of software for reduction of data.
16.2 Documentation of software for analysis of data.
16.3 Methods for recording of data.
16 * 4 Methods for secure storage of data.
16.5 Methods for reducing data.
145
-------
16.6 Methods for validating data.
16.7 Definition of data-quality indicators.
16.8 Methods for evaluating quality of data.
16.9 Methods for presenting data.
16.10 Reporting of conclusions.
OPERATING PROCEDURE 1.1
PREPARATION OF ARTIFICIAL-RESERVOIR HOUSING
TO RECEIVE SAND MIXTURE
1.1.1 Install gasket between bottom blind flange and bottom
flange.
1.1.2 Bolt flange halves together:
o Insert bolts and screw nuts on, hand-tight.
o Torque to 2500 ft.-lb. Tighten one nut; move to
180-deg. position; tighten that nut.
o Move to next nut in clockwise direction and tighten it.
o Move to 180-deg. position; tighten that nut.
o Move to next nut in clockwise manner and tighten it.
o Repeat this pattern until all nuts are torqued to 500
ft.-lb.
o Repeat the same pattern at 1000 ft.-lb. and 2000 ft.-
lb. torque, and finally at 2500 ft.-lb.
1.1.3 Clean surfaces on inside of artificial-reservoir
housing. . —
1.1.4 Place 'form in housing to pour high-porosity outer shell.
1.1.4.1 Place HOPE liner on inside wall of artificial-
reservoir housing and tape at butt joint.
1.1.4.2 Uniformly put parting compound on surface of
sheet metal form, for making outer shell.
146
-------
1.1.4.3 Place centering-device in form: Put sheet-metal-
and-wood form in housing and secure form.
1.1.5 Place borehole form in 5 1/2-in. casing.
1.1.5.1 After outer shell has cured for 24 hr., remove
form for making shell.
1.1.5.2 Roll a 3 ft.-by-20 in. sheet of HDPE so that it
fits tightly on inside of casing. Place in
lower casing so that top of rolled sheet is
above top flange by about 1 in. Fill HDPE with
sand to retain desired shape. Wrap fine woven
screen around HDPE. Place movable screen
clasaps around screen, near pour-level. Move
clamps up as number of lifts increases.
OPERATING PROCEDURE 1.2
PREPARATION OF SAND MIXTURE
1.2.1 Weight calculations.
1.2.1.1 Use Halliburton guidelines for weight of
mixtures for sand and components of bonding
agent. (See Appendix B, Attachment Bl, letter
froia J. Murphey, Halliburton Co.)
1.2.1.2 Place scales under vented hood for weighing
components of bonding agents. Wear protective
clothing. Mix one lift at a time. One lift is
1/6 of total. Amount of bonding agent dependent
on permeability and porosity desired.
1.2,1.3 Weigh sand components; place in 40-gal.
containers and have divided to make six
lifts.
1.2.1.4 Mix sand components in mortar-box with small
roto-tiller.
1.2.1.5 Mix components of bonding agent in sequence and
timing specified by Halliburton. Mix under .
fume hood and wear protective clothing.
1.2.1.6 Pour mixed bonding agent evenly over sand in 5-
ft. mortar-box and mix with roto-tiller until
sand is uniformly in "fluffy" state. (Note
147
-------
that this is an art.)
1.2.1.7 Immediately take to artificial-reservoir housing
by forklift and begin placement.
OPERATING PROCEDURE 1.3
FILLING OF HOUSING WITH SAND MIXTURE
1.3.1 Outer shell mixture.
1.3.1.1 With forms in place and secured, pour high-
porosity sand mixture evenly around periphery
of mold at about 2-in. depth. Tamp mixture
until a "bouncy" reaction takes place,
suggesting a "dough-like." consistency. (Note,
this is an art.) ;
1.3.1.2 Repeat Step 1.3.1.1 until the final compaction
is even with top of reservoir housing.
1.3.2 Primary reservoir mixture.
1.3.2.1 Check to assure that movable screen clamp is
just above height of lift to be poured. Each
lift is about 4 in. high.
1.3,2.2 While two people are preparing mixture of sand,
two people pour and tamp previously mixed
batch.
1.3.2.3 With hand-compaction tools clean, the mixed
sand and resin are placed in housing and spread
evenly in a layer about 1 in. thick. Sand is
tamped until "bouncy".
1.3.2.4 Steps 1.3.2.2 and 1.3.2.3 are repeated until
entire reservoir-housing is filled to within
1/16 in. from top.
1.3.2.5 Place a layer of RTV 66 thicker than 1/16-in.
on top surface of' tamped sand mixture.
148
-------
OPERATING PROCEDURE 1.4
EMPLACEMENT OF TOP FLANGE, ARTIFICIAL-RESERVOIR HOUSING
1.4.1 Place gasJcet over RTV 66 and center on housing.
1.4.2 Using forklift, place top flange carefully on housing,
making sure that alignment allows the borehole form to
fit on inside of upper 5 1/2-in. casing. Align bolt
holes and place full weight of flange on housing.
1.4.3 Secure flange according to Operating Procedure 1.1.2.
1.4.4 After mixture has cured, remove bullplug at bottom of 5
I/2-in. casing and remove sand from mold. Remove the
HDPE borehole mold and then screen.
OPERATING PROCEDURE 2.1
CALIBRATION OF PRESSURE GAUGES
2.1.1 Prepare deadweight tester for calibration of
instruments.
2.1.1.1 Check level of oil in reservoir of deadweight
tester.
2.1.1.2 Insure that weight mechanism spins freely.
2.1.1.3 Assemble weights necessary for desired range of
tests.
2.1.2 Calibration of pressure gauges.
2.1.2.1 Mount gauge on deadweight tester.
2.1.2.2 Adjust needle on gauge face to be zero.
2.1.2.3 Assemble" set of weights equal to mid-span of
gauge and place on deadweight tester.
2.1.2.4 Adjust span of gauge so that needle on
gauge face reads amount equal to weight load.
2.1.2.5 Remove weight load. Repeat steps 2.1.2.3 and
2.1.2.4 until registry at zero and midweight,
respectively, are achieved.
149
-------
2.1.2.6 Assemble set of weights appropriate for span
and accuracy of gauge.
2.1.2.7 On gauge-calibration sheet, record sequence of
weights.
2.1.2.8 Place weight on deadweight, tester. Check
weight shaft for free spin and free float.
Record needle reading.
2.1.2.9 Add weight according to sequence specified in
Step 2.1.2.7, and repeat Step 2.1.2.8, until
maximal pressure is reached.
2.1.2.10 To determine gauge, remove weights one at a
time. With each removal, record needle reading
at proper place on gauge-calibration sheet.
2.1.2.11 If repeatability is outside range of accuracy
for gauge under testing, then repeat 2.1
through 2.1.2.10.
2.1.2.12 If operations have been conducted as prescribed
and observations repeatedly lie outside the
range of accuracy, then reject gauge.
2.1.2.11 For an acceptable transducer, analyze
calibration data and define a calibration
equation for the given gauge.
OPERATING PROCEDURE 2.2
CALIBRATION OF PRESSURE AND DIFFERENTIAL-PRESSURE TRANSDUCERS
2.2.1 Preparation for Calibration.
2.2.1.1 Measure and cut all instrument lead-lines.
2.2.1.2__Connect instrument connectors to each
lead-line.
2.2.1.3 Pre-plumb all pressure and differential
pressure transducers with appropriate fittings
and tubing. Refer to Figures D2 and D3.
2;2.1.4 Number all pressure and differential-pressure
transducers according to location.
150
-------
2.2.1.5 Gather all material, equipment, and tools for
calibration.
2.2.2 Calibration of pressure and differential-pressure
transducers.
2.2.2.1 A DESGRANGES et HUOT, deadweight pressure
tester, type 5500 is used to calibrate.
2.2.2.2 Location of deadweight pressure tester for
calibration of transducers is located at the
Research and Development Complex, Conoco, Inc.,
Ponca City, Oklahoma.
2.2.2.3 All material, equipment, and tools are
transported to Ponca City.
2.2.2.4 Calibration of pressure and differential-
pressure transducer is accomplished using
procedures outlined in:
DESGRANGES et HUOT PRESSURE STANDARDS
Deadweight Pressure Tester
Type 5500
Technical Manual
OPERATING PROCEDURE 2.3
CALIBRATION OF TEMPERATURE SENSORS
2.3.1 Activate Tenny Environmental Temperature Chamber.
2.3.1.1 Set controls to chill environmental chamber to
0 degrees C.
2.3.1.2 Put Analog Device 590 temperature sensor and
the multiplexer box into environmental chamber.
Connect entire assembly to electrical power
outlet.
2.3.2 Check calibration references.
2.3.2.1 Calibrate Fluke Digital Thermometer and
Precision Dial Thermometer by comparing values
at ambient temperature and by submerging each
sensor in ice water (0 deg. C.). Allow to
stabilize for 10 minutes. Readings from these
two points will define calibration of reference
151
-------
sensors.
2.3.2.1 Place both reference sensors into environmental
chamber. Allow to chill and stabilize for 30
minutes.
2.3.2.2 On Temperature Sensor Calibration form, record
temperatures shown on Fluke and Precision Dial
thermometer. Record millivolt output from all
AD 590s.
2.3.2.3 Set controls to elevate environmental chamber
to 10 deg. C.
2.3.2.4 Allow chamber and contents to stabilize for 30
min.
2.3.2.5 Repeat Step 2.3.2.2.
2.3.2.6 Repeat Steps 2.3.2.3 through 2.3.2.5 at 20 deg.
C., 30 deg. C., 40 deg. C. and 50 deg. C.
2.3.3 Analyze calibration data and define a calibration
equation for each sensor.
OPERATING PROCEDURE 2.4
CALIBRATION OF FLOW METERS
The following definitions are used:
VI = Vindum valve No. 1, which is top control valve in
reservoir-effluent flow-meter network.
V2 = Vindum valve No. 2, which is control valve in
reservoir-effluent flow-meter network.
V3 = Vindum valve No. 3, which is top control valve in
salt-water flow-meter network.
V4 = Vindum valve No. 4, which is bottom control valve
in salt-water flow-meter network.
PT = Pressure transducer.
BPV = Back-pressure valve.
2.4.1 Make Connection Changes
2.4.1.1 Attach hose adapter to inlet of mud-column
flow-meter vessel.
2.4.1.2 Connect outlet of mud-column flow meter to V4
152
-------
inlet with tubing.
2.4.1.3 Connect outlet of salt-water flow meter to
inlet port of effluent flow meter.
2.4.1.4 Attach line and hose to the bleed and draw
lines.
2.4.1.5 Connect outlet of effluent flow meter to
tubing leading to vessel on scales.
2.4.2 Bleed the two piston flow meters.
2.4.2.1 Turn valves (vent and supply) to fill the mud-
column flow meter with water. When full, shut
off vent valve.
2.4.2.2 Circulate water through all flow meters with
hydrant pressure.
2.4.2.3 Cycle pistons back and forth until no air comes
out of the vent lines from the salt-water and
effluent flow meters.
2.4.2.4 Shut off water supply and vent valves upon
successful bleeding..
2.4.3 Activate computer/data acquisition system.
2.4.3.1 Connect all leads from flow meters, scales and
pressure transducers to the multiplexer.
2.4.3.2 Connect control air to Vindum valves.
2.4.3.3 Activate software on selected instrument
cycling.
2.4.4 Set BPV pressure.
2.4.4.1 Close all ports to VI and V2 and close BPV
(turn clockwise to increase pressure).
2.4.4.2 Charge the 1-gal. accumulator with N2 to the
desired back pressure.
2.4.4.3 Turn the BPV counterclockwise (decrease) until
the effluent just begins to seep out of the
line.
2.4.5 Initialize the flow.
153
-------
2.4.5.1 Open all ports to the Vindum valves VI, V2, V3
and V4.
2.4.5.2 Increase nitrogen pressure to the mud-column
flow meter until the pressures equal the back
pressure.
2.4.5.3 Allow the total system to equilibrate.
2.4.5.4 Set the Vindum valves VI, V2, V3 and V4 to
their operating modes.
2.4.5.5 Slowly increase the nitrogen pressure until
there is visible, flow from reservoir-
effluent line. This initial flow
should be as slow as it can to be controlled;
just a drip or a seep.
2.4.6 Record data.
2.4.6.1 Set computer to cycle through all activated
sensors.
2.4.6.2 Manually record both gauge pressure and scale
output as well as date and time. Do this
periodically throughout the run.
2.4.6.3 Allow enough time for pistons in flow meters
to span their complete range of travel.
2.4.6.4 Allow enough time for the piston to equilibrate
before going to next flow rate.
2.4.7 Span the flow range.
2.4.7.1 Increase the pressure until the flow increases
to the desired rate.
2.4.7.2 Proceed with Steps 2.4.6.1 through 2.4.6.4.
2.4.7.3 Repeat Steps 2.4.7.1 and 2.4.7.2 until the
entire flow range has been spanned.
2.4.8 Span back-pressure range.
2.4.8.1 Do Steps 2.4.4 through 2.4.7 for each back
pressure desired.
2.4.8.2 Choose back pressures coincident with the test
schedule.
154
-------
OPERATING PROCEDURE 2.5
CALIBRATION OF MUD FLOW-RATE SYSTEM
2.5.1 Circulate pre-mixed mud through recirculating lines for
three cycles.
2.5.2 Fourth cycle: Sample mud at 6-min. intervals for 1 hr.
2.5.2.1 At time each sample is collected, measure
viscosity by Marsh Funnel. Record measurement
on Mud Flow-meter Calibration Sheet.
2.5.2.2 Measure weight/unit volume by precision
scales. Record observations to hundredth of
Ib./gal. Record measurement on Mud Flow-meter
Calibration Sheet.
2.5.2.3 Measure pH with pH meter. Record on Mud Flow-
meter Calibration Sheet.
2.5.3 Calculate means and standard deviations.
2.5.4 Plot means and plus and minus two standard deviations
on Mud-homogenization Quality-control Chart.
2.5.5 If plotted data lie outside rejection limits on Mud
Homogenization Quality-control Chart, then repeat steps
2.5.2 through 2.5.4.
2.5.6 On Mud Flow-meter Calibration sheet record mean density
of mud.
2.5.7 Activate computer and data-acquisition system for flow-
rate calibration cycle.
2.5.7.1 Set back-pressure on mud pump at 400 psi.
2.5.7.2 Allow time for circulation system to
equilibrate.
•2.5.7.3 Set stop watch to zero. Set scales to zero.
2.5.7.4 Divert flexible hose from tank-return port
into sample-collection funnel. Simultaneously
start stop watch, according to standard
countdown procedure.
155
-------
2.5.7.5 Fill container to level-indicator.
2.5.7.6 Divert flow back to mud tank; simultaneously
trip stop watch, according to standard
countdown procedure.
2.5.7.7 Weigh fluid diverted into sample-container.
2.5.7.8 On Mud Flow-meter Calibration Sheet, record
average millivolt output from tachometer,
average pressure-gauge reading, and weight of
sample.
2.5.7.9 Empty sample-container and clean same.
2.5.7.10 Repeat Steps 2.5.7.1 through 2.5.7.9 at back-
pressures of 600 psi, 800 psi and 1000 psi.
2.5.7.11 Analyze data and define a calibration-equation
for flow rate as function of back-pressure and
revolutions per minute.
OPERATING PROCEDURE 2.6
CALIBRATION OF SALT-WATER TURBINE METER
2.6.1 Connect calibration system to salt-water line.
2.6.2 Connect turbine-meter electrical lead line to data-
acquisition system and activate computer.
2.6.3 Open valves so that circulation can take place, and
begin circulation of salt water from tank, and back to
tank. Circulate for approximately 30 minutes. During
circulation, check for leaks and other faults.
2.6.4 Adjust back-pressure valve to control flow at
approximately 10 gpm, by using manufacturer's
calibration factor.
2.6.5 Allow time for circulation system to equilibrate.
2.6.6 Set stop watch to zero. Set scales to zero.
2.6.7 Divert flexible hose from tank-return port into
sample-collection funnel. Simultaneously -start
stop watch, according to standard countdown
procedure.
156
-------
2.6.8 Fill container to level-indicator.
2.6.9 Divert flow back to mud tank; simultaneously trip
stop watch, according to standard countdown
procedure.
2.6.10 Weigh fluid diverted into sample-container.
2.6.11 On Salt-water Turbine Meter Calibration Sheet record
average reading from turbine meter and weight of sample
measured during this time period.
2.6.12 Return salt water from calibration tank to salt-water
tank, and clean calibration tank.
2.6.13 Repeat steps 2.6.5 through 2.6.12, for 8, 6, 4, 2, 1
and 0.5 gpm.
2.6.14 Analyze data according to Operating Procedure 16.5, and
define calibration-equation for flow rates as function
of millivolt output from turbine meter.
OPERATING PROCEDURE 3.0
MOUNTING DIAPHRAGM-SEAL HOUSINGS
3.0.1 Prepare all components of diaphragm-seal housing
assembly for mounting.
3.0.1.1 Inspect diaphragm-housing valves for machining
marks and burrs.
3.0.1.2 Check for weld preparation on half to be welded
to 5-1/2-in. casing.
3.0.1.3 Clean surfaces to be welded, including removal
of paint, thread compound, etc.
3.0.2 Mount bottom diaphragm-seal housing half to 5 1/2-in.
casing.
3.0.2.1 Measure and mark position to mount diaphragm-
seal housing.
3.0.2.2 Position bottom diaphragm-seal housing on
5 1/2-in. casing.
3.0.2.3 Weld bottom diaphragm-seal housing half to
157
-------
5 1/2-in. casing using MIG welder with C02 gas
shield and 0.035-in. mild steel wire.
3.0.2.4 Check all welds for possible pin holes or
leaks.
3.0.2.5 If any visible flaws are apparent, grind out
and reweld.
3.0.2.6 Welding should be done in such a way as to keep
bending or warping at a minimum.
3.0.3 Assembly of diaphragm-seal housing.
3.0.3.1 Gather all parts and materials necessary to
assemble diaphragm-seal housings:
- Top half, diaphragm-seal housing
- Diaphragm
- Six 8-32 x 1 1/4-in. grade-8 Allen cap screws
- One 1/4-in. NPT x 1/4-in. CPI fitting
- Allen wrench
- Masking tape
- Locktite safety solvent
- Locktite Fast Cure Epoxy 45
- PST teflon thread compound
- Paint.
3.0.3.2 Gather all tools and equipment needed to
assemble diaphragm-seal housing.
- Air compressor
- Sand blaster
- Sand-blast sand
- Torque wrench in inch-pounds
- End wrench, 9/16-in.
- Drill and drill bits
3.0.3.3 Sand blast both halves, diaphragm-seal housing
to clean white metal.
3.0.3.4 Mask both faces, halves of diaphragm-seal
housing with masking tape and paint inside and
outside surfaces. Let paint dry for 24 hours.
3.0.3.5 Remove masking tape and clean faces with
safety solvent.
3.0.3.6 Drill two 1/8-in. holes through 5 1/2-in.
casing inside half of diaphragm-seal housing
welded to 5 1/2-in. casing. One should go
158
-------
toward the top and one toward the bottom of
the casing. Refer to Figure Dl.
3.0.3.7 Mix Locktite Fast Cure Epoxy 45 according to
instructions. Apply to housing half welded
to 5 1/2-in. casing. Initial set-up time for
Epoxy mixture is 5 min.
3.0.3.8 Install diaphragm with rubber side to 5 1/2-
in. casing. Make sure holes in diaphragm are
aligned with bolt holes in housing.
3.0.3.9 Apply Epoxy mixture to top-housing half and
mate to bottom-housing half.
3.0.3.10 Apply small amount of PST thread compound on
underside of the Allen cap screw head.
3.0.3.11 Insert Allen cap screw and make up finger
tight with Allen wrench. The Epoxy mixture
should flow only slightly out all four sides
of housing.
3.0.3.12 Allow Epoxy to cure for a minimum of 24 hr.
3.0.3.13 Torque Allen cap screws to 60 in.-lb.
3.0.3.14 Apply PST thread compound to CPI fitting and
make up into top of housing.
OPERATING PROCEDURE 3.1
MOUNTING OF DIFFERENTIAL-PRESSURE TRANSDUCERS
3.1.1 Prepare differential-pressure transducers for mounting.
3.1.1.1 Differential pressure transducers have
been calibrated previously. Refer to Operating
Procedure 2.2.
3.1.1.2 Locations 2, 3, 4, 5 and 6 are to have one
differential-pressure transducer mounted to
each; Location 7 has four each. See Figures
C2, D2, and D3 for detail of locations.
3.1.1.3 Each differential-pressure transducer is to be
filled with distilled water and bled of all
air.
159
-------
3.1.1.4 Mount differential pressure transducer to
mounting plate and plumb to system with 1/4-in.
stainless steel tubing.
3.1.1.5 All tubing is to be filled with distilled water
and bled of air.
OPERATING PROCEDURE 3.2
MOUNTING OF PRESSURE TRANSDUCERS
3.2.1 Prepare pressure transducers for mounting.
3.2.1.1 Pressure transducers have been previously
calibrated. Refer to Operating Procedure 2.1.
3.2.1.2 Locations 2, 6 and 7 are to have pressure
transducers. See Figure C2 for detail of
locations.
3.2.1.3 Each pressure transducer is to be filled with
distilled water and bled of air.
3.2.1.4 Mount pressure transducer to mounting plate
and plumb to system with 1/4 inch stainless
steel tubing.
3.2.1.5 All tubing is to be filled with distilled
water and bled of air.
OPERATING PROCEDURE 3.3
MOUNTING OF TEMPERATURE TRANSDUCERS
3.3.1 Preparation of temperature sensor for mounting.
3.3.1.1 Temperature sensor has been calibrated
previously. Refer to Operating Procedure 2.3.
3.3.1.2 Temperature sensor is placed in a pre-prepared
protective housing and potted for water
resistance. Housing is made from a phenolic
material and potted with hot glue.
3.3.2 Preparation of surface of 5 1/2-in. casing, where
temperature sensor is to be mounted.
160
-------
3.3.2.1 Surface of pipe must be clean of all grease,
dirt, pipe-thread compound or paint.
3.3.2.2 Use of a wire brush or grinder with wire wheel
would be suitable.
3.3.3 Mounting temperature sensor.
3.3.3.1 Apply a small amount of thermal-conductive
silicone paste on temperature sensor.
3.3.3.2 Place the temperature sensor and housing on
5 1/2-in. casing at predetermined location.
3.3.3.3 Attach to 5 1/2-in. casing using large cable
ties.
3.3.3.4 Integrate temperature-sensor lead-lines with
other lead-lines up casing.
OPERATING PROCEDURE 3.4
MOUNTING OF MULTIPLEXERS
3.4.1 Attach dummy multiplexer-box to dummy shielding
bracket.
3.4.2 Align this assembly so that axis of multiplexer and
long axis of casing are superincumbent. Long axis of
base of multiplexer must be the point of tangent to
circumference of the casing.
3.4.3 Clamp assembly in proper place.
3.4.4 Weld shielding bracket to casing.
3.4,5 Remove dummy multiplexer; replace with actual
multiplexer.
3.4.6 Attach instrumentation lead-lines according to wiring
diagram.
161
-------
OPERATING PROCEDURE 3.5
PLACING OF FLOW METERS
3.5.1 Move flow meters to location.
3.5.1.1 Flow meters will be utilized at reservoir
assembly stand (Figure 2, Location A) and at
well stand (Figure 2, Location B). Therefore,
flow meters, associated instrumentation and
equipment are mounted on a model platform.
3.5.2 Connecting flow meters to artificial reservoir.
3.5.2.1 Connect flow meters to artificial reservoir.
3.5.2.2 For Location A refer to Operating Procedures 6.1
and 6.2.
3.5.3 Connect instrumentation as required.
OPERATING PROCEDURE 3.6
MOUNTING OF PRESSURE GAUGES
3.6.1 Preparation of pressure gauges.
3.6.1.1 Pressure gauges have been calibrated previously
according to Operating Procedure 2.1.
3.6.1.2 Pressure gauges are to be mounted at Location
7. One should be at top of artificial
reservoir and one positioned for radial
effluent of artificial reservoir.
3.6.2 Mounting pressure gauges.
3.6.2.1 Pressure gauges are to be plumbed into system
with 1/4-in. stainless steel tubing. See
Figure D3.
3.6.2.2 PST thread compound is to be used on all
threads and tubing connections.
3.6.2.3 Tubing is to be filled with distilled water and
bled of all air.
162
-------
OPERATING PROCEDURE 4.0
PIPE SELECTION
4.0.1 Pipe tally and inspection.
4.0.1.1 All 5 1/2-in. and 1 1/4-in. pipe tallied.
Each joint numbered, measured, and length
recorded.
4.0.1.2 Each joint inspected for damage to pipe or
4.0.2 Selecting pipe for first test.
4.0.2.1 Four joints of 5 1/2-in. pipe were chosen.
1 - 44.72 ft.
2 - 36.63 ft.
3 - 47.57 ft.
4 - 47.62 ft.
Total - 176.53 ft.
4.0.2.2 A 6.25-ft. was used to position string at
precise depth and also to position top of
casing at a precise elevation, to receive the
artificial reservoir.
4.0.2.3 Five joints of 1 1/4-in. tubing were selected
for salt-water injection string and are shown
schematically in Figure C2. The 1 1/4-in.
tubing is run alongside the 5 1/2-in. casing.
4.0.2.4 A transition fitting was designed and
constructed to change from 1 1/4-in. tubing to
1/2-in. stainless steel tubing with 1/4-in.
bleed line (see Figure Cl-A and Cl-B). This
was done to accommodate filling of the
1 1/4-in. tubing string with salt water, to
allow bleeding the system of air, and also to
allow better passage through casing head.
OPERATING PROCEDURE 4.1
POSITIONING CASING JOINT
4.1.1 Moving pipe from rack to V-door.
163
-------
4.1.1.1 Pipe is rolled from rack to V-door. Care should
be taken, because diaphragm-seal housings and
transducer mounting plates have been welded to
casing.
4.1.1.2 A rope with hook connected to bottom end of
casing is used to pull casing toward well head.
Draw works of pulling unit are utilized.
OPERATING PROCEDURE 4.2
CONNECTING INSTRUMENTATION LEAD-LINES
4.2.1 Instrumentation lead-lines
4.2.1.1 All instrumentation lead-line lengths are
calculated and cut.
4.2.1.2 Each lead-line instrument end is fitted with
appropriate receptacle or plug, depending on
the instrument.
4.2.1.3 Each fitting is potted with a waterproof
material (hot glue) to provide water-tight
fittings.
4.2.2 Instrumentation lead-line connections.
4.2.2.1 All instrument lead-line connections are of the
form of plug twist-lock or plug with rubber
seal.
4.2.2.2 Cable ties are used to secure lead-lines in
place.
OPERATING PROCEDURE 4.3
MECHANICAL INSTALLATION OF FIRST JOINT
(Note: All location numbers refer to Figure C2.)
4.3.1 Preparation of first joint of casing.
4.3.1.1 Measurement rechecked and recorded as 44.72
ft.
164
-------
4.3.1.2 Locations 1, 2, and 3 were measured, narked
and recorded respectively as 39, 31, and 18
ft. from top of joint.
4.3.1.3 Bottom of the joint (40 ft.) was located.
4.3.1.4 Joint was cut off at 40.5 ft.
4.3.1.5 3/4-in. plate steel was cut to fit inside of
5 1/2-in. casing (bottom plug).
4.3.1.6 3/4-in. plate steel welded in place, top of
plate to top of collar (40 ft.).
4,3.1.6,1 2-in. x 3/4-in. plate steel cut
for cross brace for 3/4-in. plate
steel bottom plug.
4.3.1.6.2 2-in. x 3/4-in. plate steel
braces welded into place.
4.3.1.7 The remaining 4.22-ft. section was repositioned
5 1/2-in. casing and welded.
4.3.1.8 Retaining lugs were positioned and welded to
the bottom 4.72 ft. of casing, to hold
centralizer (center of centralizer 2 ft. from
actual bottom).
4.3.1.9 Injection point is measure 9 ft. from bottom
plug and marked. A 90-deg. elbow NPT schedule
160 was machined on one opening to fit flush
with arc of 5 1/2-in.. casing and weld-prepped
on a bevel.
4.3.1.10 90-deg. elbow welded to 5 1/2-in. casing
with 9-ft. mark at center of opening.
4.3.1.11 Change-over nipple collar made up with 90-deg.
elbow (change-over from 11/12-in. thread to
API 8rd thread).
4.3.1.12 Pressure-transducer mounting plates consisting
of. 6-in. x 2-in. x 1/4-in. steel plates, are
positioned to 5 1/2-in. casing so as to
position center of differential-pressure
transducers parallel with center the diaphragm-
seal housing.
4.3.1.13 Plate is welded top and bottom.
165
-------
4.3.1.14 Two mounting plates positioned at Location 2,
one on either side of diaphragm-seal housing.
4.3.1.15 One plate mounted at Locations 3,4,5 and 6.
4.3.2 Plumbing the pressure-measurement system.
4.3.2.1 Plumb a 1/4-in. tubing from Location 1
diaphragm-seal housing to positive side of
differential-pressure transducers at
Location 2.
4.3.2.2 Bleed port provided on both positive and
negative sides of all differential-pressure
transducers.
4.3.2.3 Bleed ports provided for pressure transducers.
4.3.2.4 A fill valve is placed just above diaphragm-
seal housing at Locations 1, 2, 3, 4 and 5 and
all tubing unions.
4.3.2.5 1/4-in. tubing from negative side of
differential-pressure transducer at Location 2
to top side of diaphragm-seal housing at
Location 2.
4.3.2.6 1/4-in. tubing from Location 2 diaphragm-seal
housing to absolute-pressure transducer with
bleed port.
4.3.2.7 1/4-in. tubing from Location 2 diaphragm-seal
housing to positive side of differential-
pressure transducer at Location 3.
4.3.2.8 1/4-in. tubing from negative side of
differential-pressure transducer at Location 3
to top side of Location 3 seal housing.
4.3.2.9 1/4-in. tubing from Location 3 diaphragm-seal
housing fill valve to top of first joint of
casing and extended to point where Location 4
would be.
4.3.3 Hydrostatic-pressure testing of first joint.
4.3.3.1 Plugs for both the 5 1/2-in. casing and the
1 1/4-in. tubing were made and installed. The
one for 5 1/2-in. casing had a bleed port/-
the one for 1 1/4-in. tubing had a fill port
166
-------
and a bleed port.
4.3.3.2 Pressure transducers and differential-pressure
transducers are removed, to bleed individually
by hand.
4.3.3.3 Absolute-pressure transducer is bled in
the following manner: It is held down-side
up and, with a syringe and needle, filled with
distilled water.
4.3.3.4 Needle is inserted into tubing close to the
bottom of absolute-pressure transducer and
water injected, forcing all air up and out of
pressure transducer toward top of the tubing.
4.3.3.5 Transducer is tapped gently to loosen all
entrained air and more water is injected,
assuring that all air is bled from system.
4.3.3.6 Absolute-pressure transducer is placed back
onto its mounting plate and plumbed back into
system.
4.3.3.7 Differential-pressure transducer has a
diaphragm, and therefore both sides must be
bled.
4.3.3.8 Differential-pressure transducer is turned on
its side with diaphragm slightly higher than
electronics end. A water-filled syringe-needle
is inserted into tubing and water injected into
pressure transducer until water comes out bleed
port. Transducer is then tapped gently to make
sure all the air is removed.
4.3.3.9 Bleed port is tightened to maintain the
bled system while filling the opposite side.
4.3.3.10 Transducer is turned over and opposite side is
treated in same manner.
4.3.3.11 When both sides are filled, differential-
pressure transducer is mounted on mounting
plate and plumbed back into system.
4.3.3.12 5 1/2-in. casing was picked up in vertical
position, with all bleed ports open; starting
with Location 1 fill valve, water was injected
with syringe into tubing, which was tapped
167
-------
gently as water was injected, making sure air
entrained would be loosed and go up with water.
Water was injected until it discharged from
bleed port at Location 2.
4.3.3.13 Casing is lowered until Location 2 is
waist high.
4.3.3.14 Bleed port tightened on Location 2.
4.3.3.15 Water is injected into fill valve at Location
2, using same procedure as 4.3.3.12.
4.3.3.16 Fill valve at Location 2 was closed and casing
lowered until Location 3 was waist 'high.
4.3.3.17 Bleed port tightened at Location 2.
4.3.3.18 Water injected at fill port and Location 3
using same procedure as 4.3.3.12.
4.3.3.19 Casing lowered and plug put on top of tubing
and tightened to close system.
4.3.3.20 Regular tap water used to fill pipe and
1 1/4-in. tubing.
4.3.3.21 Air is bled out of the system and
hydrostatic pressure pump connected.
4.3.3.22 System is pressured to 3000 psi.
4.3.3.23 All welds, connections, flanges pipe and
tubing should be checked for leaks. Provided
any leaks are found, system should be drained
and leaks repaired. System is refilled and
hydrostatic pressure-tested. Repeat as
necessary until no leaks are detected.
4.3.3.24 Drain 5 1/2-in. casing and 1 1/4-in. tubing
in preparation to lower pipe into well bore.
4.3.4 Installation of instrumented first joint.
4.3.4.1 Connect all instrumentation lead-lines as
dictated in Operating Procedure 4.2.
4.3.4.2 Mount temperature sensor to casing. Refer to
Operating Procedure 3.3.
168
-------
4.3.4.3 Secure 1 1/4-in. tubing and all instrument
lead-lines, using metal strapping and cable ties
as needed.
4.3.4.4 Raise instrumented casing to vertical position
above well base.
4.3.4.5 Attach centralizer to bottom of 5 1/2-in.
casing.
4.3.4.6 Lower instrumented casing slowly into well,
watching to insure that instruments remain
clear of casing-walls.
4.3.4.7 After instrumented joint is lowered into well,
set slips to hold casing and begin preparations
to run remaining casing.
OPERATING PROCEDURE 4.4
MECHANICAL INSTALLATION OF SECOND
AND ALL OTHER JOINTS
4.4.1 Casing Preparation.
4.4.1.1 Inspect .casing and tubing for damage.
4.4.1.2 Place and weld diaphragm housings where needed.
Refer to Operating Procedure 3.0.
4.4.2 Installation.
4.4.2.1 Raise casing to vertical position above
wellbore.
4.4.2.2 Remove thread protector and apply thread
compound to casing threads.
4.4.2.3 Lower casing to mate with casing in wellbore.
4.4.2.4 Make up casing joint to recommended torque of
2290 ft.-lbs.
4.4.2.5 Raise casing string to position to add 1 1/4-
in. tubing.
4.4.2.6 Raise 1 1/4-in. tubing and mate with tubing in
well. Make up to recommended torque of 570
169
-------
ft.-lbs.
4.4.2.7 Add 1/4-in. tubing for instrumentation as
needed.
4.4.2.8 Lower casing into well; stop at 3- to 5-ft.
intervals. Place band to hold 1 1/4-in.
tubing, instrumentation lead-lines, and
instrumentation in place at each interval.
4.4.2.9 Lower casing string to appropriate location.
Fill and bleed transducers. Refer to Operating
Procedures 4.3.3.12 through 4.3.3.18.
4.4.2.10 Mount temperature sensor. Refer to Operating
Procedure 3.3.
4.4.2.11 Connect instrument lead-lines. Refer to
Operating Procedure 4.2.
4.4.2.12 Secure instrument tubing and lead-lines. See
Operating Procedure 4.4.2.7.
4.4.2.13 Repeat Operating Procedures 4.4.2.6 through
4.4.2.10 to next casing joint.
4.4.2.14 Repeat Operating Procedures 4.4.2.1 through
4.4.2.11 until all casing is in well-bore.
OPERATING PROCEDURE 4.5
RECORDING INSTRUMENTATION POSITION
AND LOCATION ON CASING STRING
4.5.1 Recording locations of instruments.
4.5.1*1 All locations of temperature sensors, pressure
gauges, pressure transducers and differential-
pressure transducers are to be measured and
recorded.
4.5.1.2 Each joint of casing is measured and recorded.
4.5.1.3 Each down-hole instrumentation position is
measured and recorded with respect to each
casing joint.
4.5.1.4 All above-ground instrumentation positions are
170
-------
measured and recorded with respect to elevation,
4.5.1.5 Top of the casing well-head is base line for
all measurements.
OPERATING PROCEDURE 4.6
SECURING TOP JOINT AND LEAD-LINES IN WELLHEAD
4.6.1 Securing lead-lines.
4.6.1.1 A cable hanger is attached to the
instrumentation lead-lines approximately 3 ft.
below the casing well-head and secured to the
5 1/2-in. casing.
4.6.2 Securing top casing joint in well-head.
4.6.2.1 Casing is secured in well-head by slips.
4.6.2.2 A segment (l/12th) of the slips is removed to
allow passage of salt-water injection tubing
and instrumentation lead-lines.
4.6.2.3 A seal bushing, retaining ring and lock ring
are installed to secure the slips and casing
at the desired location.
OPERATING PROCEDURE 5.1
EMPLACEMENT OF WATER IN CASING STRING FOR
CALIBRATION CHECK OF DOWN-HOLE SENSORS
5.1.1 Place 2 3/8-in. tubing in casing string.
5.1.1.1 Attach 5 1/2-in. x 2 3/8-in. tubing head to
•casing string with 5 1/2-in. sub and hammer
union.
5.1.1.1 Using pulling unit, run 2 3/8-in. tubing to
bottom of casing string. Lift off bottom no
more than 10 in.
5.1.1.3 Set tubing to desired depth.
5.1.2 Fill casing string with water.
171
-------
5.1.2.1 Plumb water supply to tubing.
i
5.1.2.2 Plumb discharge piping to 5 1/2-in. tubing
head.
5.1.2.3 Fill casing string with water.
5.1.2.4 Leave tubing in casing for placement of mud.
Refer to Operating Procedure 8.4.
OPERATING PROCEDURE 5.2
ACTIVATION AND CHECK-OUT OF COMPUTERIZED
DATA-ACQUISITION SYSTEM.
5.2.1 Connection of instrumentation lead-lines.
5.2.1.1 Make all connections of down-hole sensors to
multiplexer.
5.2.1.2 Connect multiplexer to computer.
5.2.2 Activation of data-acquisition system.
5.2.2.1 Power-up computer and all related equipment.
5.2.2.2 Install software and activate control program.
5.2.2.3 Collect enough data to check out-put of all
down-hole sensors.
OPERATING PROCEDURE 5.3
INITIAL CALIBRATION CHECK OF SENSORS
5.3.1 Calculated values.
5.3.1.1 Calculate down-hole pressure at appropriate
location.
5.3.1.2 Calculate down-hole temperatures.
5.3.1.3 Adjust for atmospheric and climatic conditions,
5.3.2 Comparison of calculated values with sensor readings.
172
-------
5.3.2.1 Compare calculated pressures with pressure-
transducer readings.
5.3.2.2 Compare calculated temperatures with
temperature-sensor readings.
5.3.2.3 Compare differential-pressure transducer
readings with zero-calibration point.
5.3.2.4 Record all findings.
OPERATING PROCEDURE 6.1
MEASURING POROSITY OF ARTIFICIAL
RESERVOIR WITHIN HOUSING
6.1.1 Determine bulk volume.
6.1.1.1 Artificial reservoir is assembled on
reservoir-assembly stand. Assembly would
include bottom flange and 5 1/2-in. casing
sub with appropriate valves and bull plug,
reservoir housing with radial flow lines and
plug, top blind flange with 5 1/2-in. casing
sub and 5 1/2-in. hammer-union half, and
gaskets for artificial-reservoir housing.
6.1.1.2 Artificial reservoir is filled with water from
a 4000-ml. graduated cylinder, to a point
horizontal with top 5 1/2-in. casing sub,
just inside 5 1/2-in. hammer-union half.
6.1.1.3 Volume of water to fill reservoir to
pre-determined point is recorded for porosity
calculation and is referred to as
"bulk volume."
6.1.2 Determination of pore volume.
6.1.2.1 Place reservoir media in artificial reservoir
housing. Refer to Operating Procedure 1
(Construction of artificial reservoir).
6.1.2.2 Void space is filled with water through the
reservoir radial-flow lines and salt-water-
injection flow-meter assembly.
6.1.2.3 Record volume of water to fill reservoir to
173
-------
pre-determined point with reservoir medium in
place.
6.1.2.4 Determine volume of reservoir medium placed in
reservoir housing.
6.1.2.5 Determine porosity of the outer shell, of
coarse grained reservoir rock. (Appendix B,
Attachment B2.)
6.1.2.6- Calculate pore volume from predetermined
values.
6.1.2.7 Determine reservoir-medium porosity using
volume of reservoir medium and calculated value
of pore volume of reservoir medium.
OPERATING PROCEDURE 6.2
MEASURING PERMEABILITY OF ARTIFICIAL
RESERVOIR WITHIN HOUSING
6.2.1 Place and connect instrumentation console.
6.2.1.1 Fill reservoir with water. Refer to Operating
Procedure 6.1.
6.2.1.2 Place instrumentation console next to artificial
reservoir at assembly stand.
6.2.1.3 Connect a line from a water supply to salt-
water-injection flow meter.
6.2.1.4 Connect a line from salt-water-injection flow
meter to 1/2-in. fitting welded to bottom
bottom 5 1/2-in. casing sub.
6.2.1.5 Connect a line from reservoir radial flow line
to effluent flow meter and back-pressure valve.
6.2.1.6 Connect line from back-pressure control valve
to effluent tank. Fill and bleed all lines.
6.2.2 Determine permeability of reservoir media.
6.2.2.1 With all valves closed, set back pressure
control valve to predetermined pressure.
174
-------
6.2.2.2 Set salt-water injection pressure to test
pressure above that of the back pressure.
6.2.2.3 Open valve to wellbore.
6.2.2.4 Open valve to effluent flow meter.
6.2.2.5 Let flow stabilize. Salt-water injection and
effluent flow rate should be equal.
6.2.2.6 Record stabilized flow rate.
6.2.2.7 Record pressures of injection and effluent.
6.2.2.8 Determine all other parameters, such as
porosity, viscosity of the fluid, etc.
6.2.2.9 Calculate permeability.
OPERATING PROCEDURE 7.1
CONTAINMENT OF FLUID WITHIN ARTIFICIAL
RESERVOIR DURING REMOVAL OF INSTRUMENTS
7.1.1 Containment of Fluid.
7.1.1.1 After permeability test all valves are closed.
7.1.1.2 Relieve pressure from system, both the
instrumentation console and artificial
reservoir.
7.1.1.3 Disconnect all lines to and from
instrumentation console.
7.1.1.4 Move or place instrumentation console away from
reservoir assembly stand.
7.1.1.5 Remove tee assembly from top of reservoir.
7.1.1.6 Insert bladder to a position between drilling-
mud supply port and water-injection port on
bottom 5 1/2-in. casing sub.
7.1.1.7 Inflate bladder.
7.1.1.8 Remove 5 1/2-in. bull plug from bottom 5 1/2-
in. casing sub.
175
-------
OPERATING PROCEDURE 7.2
I
INSTALLATION OF RESERVOIR PICK-UP ASSEMBLY
7.2.1 Reservoir pick-up assembly.
7.2.1.1 The 5 1/2-in. casing elevators with
appropriate cable chokers are used for
pick-up assembly.
7.2.1.2 A crane is scheduled to move reservoir from
assembly stand to reservoir stand.
7.2.1.3 Elevators are connected to top 5 1/2-in.
casing sub welded to artificial reservoir.
OPERATING PROCEDURE 8.1
MIXING OF' MUD ACCORDING TO OKLAHOMA CORPORATION
COMMISSION'S STANDARDS FOR WELL-PLUGGING
8.1.1 Mud must weigh at least 9.0 Ib./gal.
8.1.2 Mud must have funnel viscosity of 36 sec./gt. or more.
8.1.3 For fresh mud of these properties, the proportions are
42.0 gal. of water, 1.17 gal of bentonite, and 0.614
gal. of barite.
OPERATING PROCEDURE 8.2
HOMOGENIZATION OF DRILLING MUD
8.2.1 Homogenization of drilling mud.
8.2.1.1 Activate mud pump with appropriate valves
opened.
8.2.1.2 Set back-pressure valve to approximately 200
psi.
8.2.1.3 Circulate mud to and from mud tank.
8.2.1.4 Activate mud mixer in mud tank.
176
-------
8.2.1.5 Operate for sufficient time, with mud pump and
mud mixer activated, to mix mud thoroughly.
8.2.1.6 Terminate mixing when mud becomes a homogeneous
mixture. Refer to Operating Procedure 8.3.
OPERATING PROCEDURE 8.3
SAMPLING AND TESTING OF DRILLING MUD
8.3.1 Mud is sampled during circulation, while performing
Operating Procedures 8.2, 8.4, and 10.5.
8.3.2 Obtain a 2-qt, sample each time. Sample at the
beginning and end of the operation, and at one-fourth
the way, one-half the way, and three-quarters the way
through the operation.
8.3.3 Test Etud according to API RP 13B, pages 4, 6, 8, 9, 19,
42 and 43.
OPERATING PROCEDURE 8.4
EMPLACEMENT OF DRILLING MUD IN CASING STRING
8.4.1 This procedure described in Operating Procedure 11.1,
OPERATING PROCEDURE 8.5
REMOVAL OF DRILLING MUD FROM CASING STRING
8.5.1 This procedure described in Operating Procedure 15.1,
OPERATING PROCEDURE 9.1
PLACEMENT OF RESERVOIR STAND
9.1.1 Removal of 2 3/8-in. tubing from casing.
9.1.1.1 Remove tubing fittings used to fill casing.
9.1.1.2 Pull 2 3/8-in. tubing with pulling unit.
177
-------
9.1.1.3 Stack 2 3/8-in. tubing on rack.
9.1.2 Disassembly of 5 1/2-in. casing head.
9.1.2.1 Disconnect 5 1/2-in. casing-head assembly at
5 1/2-in. hammer union.
9.1.2.2 Place 5 1/2-in. casing-head assembly under
pipe on rack.
9.1.3 Placement of reservoir stand.
9.1.3.1 Lift reservoir stand over well bore.
9.1.3.2 Align anchor bolt holes with pre-drilled Red
Head anchors.
9.1.3.3 Make up anchor bolts.
9.1.3.4 Adjust screw jacks to receive artificial
reservoir.
OPERATING PROCEDURE 9.2
PLACEMENT OF ARTIFICIAL RESERVOIR
ON RESERVOIR STAND
9.2.1 Preparation of reservoir stand and casing string.
9.2.1.1 Place reservoir stand. Refer to Operating
Procedure 9.1.
9.2.1.2 Fill casing string with drilling mud. Refer to
Operating Procedure 8.4.
9,2.1.3 Check hammer union to mate with artificial
reservoir.
9.2.1.4 Schedule crane to move artificial reservoir.
9.2.2 Preparation of reservoir for moving.
9.2.2.1 Disconnect instrumentation console and
associated lines while maintaining fluid in
artificial reservoir.
9.2.2.2 Move environmental building to northeast corner
of slab.
178
-------
9.2.2.3 Place bladder in artificial reservoir between
drilling-mud supply port and water-injection
test port and inflate.
9.2.2.4 Remove bull plug from bottom of artificial
reservoir.
9.2.2.5 Move artificial reservoir to reservoir stand.
9.2.3 Moving artificial reservoir to reservoir stand.
9.2.3.1 Attach 5 1/2-in. casing elevators to crane.
9.2.3.2 Connect elevators to 5 1/2-in. casing on top
of artificial reservoir.
9.2.3.3 Pick up and move artificial reservoir to
reservoir stand.
9.2.3.4 Pay particular attention to alignment of
reservoir with casing string.
9.2.3.5 After alignment is obtained, screw hammer union
together hand-tight.
9.2.3.6 Adjust screw jacks on reservoir stand to level
artificial reservoir.
9.2.3.7 Tighten hammer union with sledge hammer.
9.2.3.8 Loosen and release crane from artificial
reservoir.
9.2.3.9 Retrieve elevators from crane.
9.2.3.10 Re-check level of artificial reservoir.
OPERATING PROCEDURE 10.1
HOMOGENIZATION OF DRILLING MUD
10.1.1 This procedure described in Operating Procedure 8.2.
179
-------
OPERATING PROCEDURE 10.2
DISPLACEMENT OF PACKER
10.2.1 Connect mud supply to bottom of reservoir.
10.2.2 Connect return line to horizontal leg of tee on top
of reservoir.
10.2.3 Open all valves on upper tee.
10.2.4 Adjust bypass valve to place low-pressure mud supply
in supply line. Open supply valve below reservoir and
allow mud to force packer slowly up wellbore. Watch
packer arrive at top by viewing through top valve.
Screw fixture in packer to hold in place.
10.2.5 Hold packer in place; shut off supply valve and mud
pump.
10.2.6 Use packer to swab out the mud above it. Remove hammer
union and then remove packer.
OPERATING PROCEDURE 10.3
ADJUSTMENT OF FLOW RATE AND BACK-PRESSURE
10.3.1 See page 16 of report for details.
OPERATING PROCEDURE 10.4
MONITORING OF MUD-FILTRATE FLOW RATE
10.4.1 See page 16 of report for details.
OPERATING PROCEDURE 10.5
SAMPLING AND TESTING OF DRILLING MUD
10.5.1 This procedure described in Operating Procedure 8.3
180
-------
OPERATING PROCEDURE 10.6
SHUT-DOWN PROCEDURE AND LINE REMOVAL
10.6.1 See pages 16 and 17 of report for details.
10.6.2 Shut all valves in vicinity of mud pump — in both
supply and return lines. Shut valve in line connecting
supply to reservoir and valve in line connecting return
to reservoir.
10.6.3 Remove upper line (return line) first and drain into
buckets. Then pour into effluent tank for disposal.
10.6.4 Repeat 10.6.3 for lower line.
OPERATING PROCEDURE 10.7
REFINED ADJUSTMENT OF PRESSURE TO PRESCRIBED MAGNITUDE
10.7.1 Check pressure in casing above artificial reservoir; if
pressure is less that desired under conditions of testing,
increase regulator setting for mud-column flow meter to
desired value.
10.7.2 If pressure is more than desired under conditions of
testing, use bleed-line valve connecting line from top
of mud column to effluent tank, to reduce to desired
pressure.
OPERATING PROCEDURE 11.1
MONITORING OF MUD COLUMN FOR DIFFERENTIAL PRESSURE,
PRESSURE AND TEMPERATURE
11.1.1 Data-acquisition system is activated during time mud is
placed in well. System is to continue monitoring mud
from time well is full until equilibration is recorded.
11.1.2 Data are recorded continuously on computer hard disk,
but computer screen is to be viewed during the first
hour and each hour thereafter for 6 hr., then
periodically until there is no apparent change in
output of differential-pressure transducer.
181
-------
OPERATING PROCEDURE 11.2
MONITORING OF MUD COLUMN AT SIMULATED-DEPTH CONDITIONS,
FOR DIFFERENTIAL PRESSURE, PRESSURE, AND TEMPERATURE
11.2.1 After reservoir is placed over well, and all systems
are connected, and mud is put under simulated well
pressure, the effect of pressure on equilibration will
be monitored.
11.2.2 Use Operating Procedure 11.1.2 to monitor well under
pressure.
OPERATING PROCEDURE 12.1
ACTIVATION OF SALT-WATER INJECTION SYSTEM
12.1.1 Salt water is placed in the two salt-water
accumulators, using salt-water tank and transfer pump,
12.1.2 Adjust regulator on instrument console to supply salt-
water accumulators with desired injection pressure.
OPERATING PROCEDURE 12.2
MONITORING AND RECORDING COMPREHENSIVE PRESSURE
DIFFERENTIALS, PRESSURES AND FLOW RATES.
12.2.1 Data are recorded on hard disk of computer; screen is
to be monitored several times each day. If a
significant event occurs, then floppy-disk file will be
used to investigate the activity.
12.2.2 If a 0.3-gpm flow rate is detected, test is complete.
If a low rate or no rate is detected, then a higher
injection pressure is set.
OPERATING PROCEDURE 12.3
INCREASING INJECTION PRESSURE IN RESPONSE
TO UNDETECTABLE FLOW FROM RESERVOIR
12.3.1 If no flow into reservoir is detected, and no gradient
182
-------
change is detected in transducers just above injection
zone, then injection pressure is increased.
12.3.2 If a gradient change occurs in pressure transducers
above injection zone, then movement of gradient change
is to be monitored. Time required for gradient change
to get to top will be determined. If time has expired
and no flow rate is detected, then injection pressure
will be increased.
OPERATING PROCEDURE 12.4
INCREASING INJECTION PRESSURE IN RESPONSE
TO LOW RATES OF FLOW FROM RESERVOIR
12.4.1 If a low flow rate is detected, this rate will be
monitored for 24 hr., to determine the time histpry.
After that time, injection pressure will be increased
and monitoring will continue.
12.4.2 Procedure 12.4.1 will be repeated until flow rate
attains a level of 0.3 gpm.
OPERATING PROCEDURE 12.5
TERMINATION OF INJECTION IN RESPONSE TO
MAXIMIZED FLOW OR PRESSURE
12.5.1 When.the flow rate is 0.3 gpm or greater, tests are
considered to be complete; pressures are relieved from
the system. Computer-data acquisition is terminated
after pressures are relieved.
OPERATING PROCEDURE 13.1.1
REMOVAL OF INSTRUMENTATION FROM ARTIFICIAL-RESERVOIR HOUSING
13.1.1 Only the instrumentation that is not securely attached
to housing must be removed — such as the two
differential-pressure processing units on top of
housing.
13.1.2 Remove all electrical connections from multiplexers to
instrumentation and from multiplexers to computer.
183
-------
OPERATING PROCEDURE 13.2
DISCONNECTING RESERVOIR HOUSING FROM CASING STRING
13.2.1 Pump mud from supply line located under reservoir-
housing and place it in effluent tank.
13.2.2 Disconnect effluent line from reservoir. Also, remove
the mud column from above reservoir-housing, using
forklift boom and hook; bring it out through roof of
building.
13.2.3 Remove lean-to from building and take instrument
console out of building.
13.2.^ Lift building off reservoir-housing with forklift and
boom. Hook into four lifting eyes attached to
building.
13.2.5 Knock off the hammer union connecting casing and
reservoir housing.
OPERATING PROCEDURE 13.3
INSTALLATION OF RESERVOIR PICK-UP ASSEMBLY
AND MOVEMENT OF RESERVOIR HOUSING
13.3.1 Call for crane services to move artificial reservoir.
13.3.2 Place crane on concrete pad so that it can just swing
boom to pick-up and replace housing.
13.3.3 Pick reservoir housing up using 5 1/2-in. casing tongs.
13.3.4 Place housing on assembly stand and secure.
OPERATING PROCEDURE 14.1
REMOVAL OF ARTIFICIAL RESERVOIR FROM HOUSING
14.1.1 Remove all vertical flow lines that connect from top of
housing to bottom of housing and that would hinder
removal of top flange.
14.1.2 Remove all bolts connecting the two top flanges.
184
-------
14.1.3 U.se forklift to remove top flange, being careful
to not disturb gasket.
14.1.4 Remove all bolts connecting the two bottom flanges.
14.1.5 Attach cables to top of flange and to forklift.
14.1.6 Lift flange; artificial reservoir should remain on
bottom blind flange. If not, a set of rail ties, of
dimensions that will fit on inside of housing, will be
placed on the ground. Housing will be dropped
strategically on ties, to force artificial reservoir
out of housing.
OPERATING PROCEDURE 14.2
MAPPING AND LABELING OF RESERVOIR SURFACE
FOR RANDOM SAMPLING
14.2.1 Divide artificial reservoir into pie sections; label
each according to radial position, depth into
reservoir and azimuth. Assign a code number for each
section.
14.2.2 Sample reservoir by random-number coding. Sample size
equal to or more than 30.
14.3.1 Take channel samples at specified locations, from top to
bottom on periphery of artificial reservoir. Mix and
sample randomly.
14.3.2 Take stratified samples (according to lifts) at
periphery, coring toward the borehole.
14.3.3 Spot samples will be taken from any location that can
give suitable access.
OPERATING PROCEDURE 14.3
COLLECTION OF RANDOM SAMPLES
14.3.1 This procedure described in Operating Procedure 14.2.
185
-------
OPERATING PROCEDURE 14.4
(
LABELING AND STORAGE OF SAMPLES
14.4.1 Reservoir samples are to be labeled with the following
information:
Location (radius, depth and azimuth)
Code number
Date
Test number
Test duration
Simulated reservoir depth
Simulated injection depth
Mud pressure at reservoir depth
Injection pressure at injection depth
Type of injection fluid
14.4.2 Samples will be stored in the School of Geology.
OPERATING PROCEDURE 15.1
DISPLACING DRILLING MUD WITH WATER
15.1.1 Run 2 3/8-in. tubing into 5 1/2-in. casing and set it
on bottom. Make sure seating nipple is placed on
bottom joint.
15.1.2 Connect water pump to 2 3/8-in. tubing. Connect well-
head annulus to effluent tank.
15.1.3 Pump water through tubing to force mud out of casing
into tank. Continue pumping until clean water comes
out of line.
OPERATING PROCEDURE 15.2
CALIBRATION CHECK OF SENSORS
15.2.1 This procedure described in Operating Procedure 5.3.
186
-------
OPERATING PROCEDURE 15.3
DISPLACING WATER WITH AIR
15.3.1 Disconnect water line and line to tank. Connect high-
volume air compressor to annulus of well head. Connect
plastic flow line to 2 3/8-in. tubing and run flow
line to ditch.
15.3.2 Shut valve on top of 2 3/8-in. tubing and pressure
annulus with air, sufficient to lift water from maximum
depth. Operate until all water is out of the casing
(detectable when air flows from the line).
15.3.3 Pull tubing, making sure that if some of joints are
still "wet," water is kept from going back into casing.
OPERATING PROCEDURE 15.4
SHUT-DOWN OF COMPUTERIZED DATA-ACQUISITION SYSTEM
15.4.1 Deactivate sensors; stop computer data-acquisition
program.
15.4.2 Transfer data from hard-disk data file to a 3 1/2-in,
floppy disk. Shut computer off.
OPERATING PROCEDURE 16.1
DOCUMENTATION OF SOFTWARE FOR REDUCTION OF DATA
16.1.1 Document software for reduction of data by defining all
variables used in program.
16.1.2 Use comment statements to guide users through source
program, to identify pertinent steps.
16.1.3 Describe reduction steps and show by example.
187
-------
OPERATING PROCEDURE 16.2
DOCUMENTATION OF SOFTWARE FOR ANALYSIS OF DATA
16.2.1 Show software documentation for Quattro and Timeslab.
16.2.2. Itemize the particular sections of these software
packages used to analyze the data and show an
example.
OPERATING PROCEDURE 16.3
METHODS FOR "RECORDING OF DATA
16.3.1 Make appropriate forus for type of test being conducted
and r-ecord data by hand to spot-check computer results.
16.3.2 Record data on hard disk and at end of each day
transfer data to 3 1/2-in. floppy disk.
OPERATING PROCEDURE 16.4
METHODS FOR SECURE STORAGE OF DATA
16.4.1 Store all important data in safe, in Development
Engineer's office.
16.4.2 Duplicates of data in safe will be placed in file in
Project Director's.
OPERATING PROCEDURE 16.5
METHODS OF REDUCING DATA
16.5.1 Raw data from each sensor will require a calibration
curve to reduce data to engineering units.
16.5.2 Sub-programs for Quattro are one means that will be
used to reduce data to usable terms.
16.5.3 Programs to be written in "C" and basic languages for
those cases in which Quattro software requires too much
storage for size of file used.
188
-------
16.5.4 Average values over a period of time (determined by
viewing segments of data plotted on screen of the
computer monitor) are to be used in place of single
values, when slope of data string is zero and data
variations are not greater than estimated error.
16.5.5 Data analysis will be done using regression techniques,
Time-series analysis will be used to determine
correlation of different events occurring
simultaneously or with time-lag. Regression
coefficients will be determined from the data shown
in Table Gl.
OPERATING PROCEDURE 16.6
METHODS FOR VALIDATING DATA
16.6.1 Total flow from injection flow meter and mud-column
flow meter must equal that from effluent flow meter.
If not, suspicion of a leak is in order.
16.6.2 Water in system before testing and after testing
provides check on calibration of instruments for data-
validation.
16.6.3 Readings from pressure-transducers mounted down-hole
are to be used to validate differential-pressure
transducer readings. These are for only the
differential-pressure transducers that are bounded by
pressure transducers on both ends.
16.6.4 Theoretical calculations are to be made, to be compared
with measured pressure and differential-pressure
values, to determine whether data are within the range
of expected values.
16.6.5 Pressure gauges are placed in the system, to be used
for comparison with those pressure transducers
associated with the gauges.
16.6.6 Pressure gradients of mud will be plotted. The curve
interpolated curve will be used to determine the amount
of mud required to be mixed in water, to achieve the
gradient. These calculations will be compared with
amounts of mud actually put into the system. These
values should be equal.
189
-------
OPERATING PROCEDURE 16.7
DEFINITION OF DATA-QUALITY INDICATORS
16.7.1 If continuity from flow-meter measurements shows total
volume within 1 percent error, data are considered to
be of acceptable quality.
16.7.2 If values from calibration with water (a) prior to the
test and (b) subsequent to the test compare within 1
percent, data are considered to be of acceptable
quality.
16.7.3 If those values from Operating Procedure 16.6.6 are
within 2 percent, data are considered to be of
acceptable quality.
16.7.4 If those values from Operating Procedure 16.6.4 are
within the range of calculated limits, then the data
are acceptable.
OPERATING PROCEDURE 16.8
METHODS FOR EVALUATING QUALITY OF DATA
16.8.1 Compare flow volume from effluent flow meter with sum
of values from injection flow meter and mud-column
flow meter, to determine percent variation. Compare
to the percent error allowed in Operating Procedure
16.7.1.
16.8.2 Reduce data from (a) prior to test and compare to (b)
data subsequent to test with water, in the system, to
determine percent variation. Compare to the criteria
in Operating Procedures 16.7.2.
16.8.3 Calculate mud required to give pressure gradient
measured during the test and compare calculation with
total mud placed in system, to determine percent
variation. Compare percent variation to criteria shown
in Operating Procedure 16.7.3.
16.8.4 Where possible, make theoretical calculations using an
upper and lower limit of expected data and compare
calculations to actual data. Use Operating Procedure
16.7.4 to judge results.
190
-------
OPERATING PROCEDURE 16.9
METHODS FOR PRESENTING DATA
16.9.1 Data will be provided in data files, ASCII format, for
viewing on monitor.
16.9.2 Pertinent data will be presented in tabular format.
16.9.3 Dependent variables will be plotted with respect to
independent variables, to show their relationships.
16.9.4 Statistical parameters will be presented in tabular
format.
OPERATING PROCEDURE 16.10
REPORTING OF CONCLUSIONS
16.10.1 Define as much of the performance envelope as data
allow, to show effects of injection on plugged wells.
16,10,2 Provide lists of developments and knowledge, which will
be guidelines for future activities.
191
------- |