PB87-132783
Borehole Sensing Methods for Ground-Water
Investigations at Hazardous Waste Sites
Nevada Unjv. System, Reno
Prepared tor
Environmental Monitoring Systems Lab.
Las Vegas, NV
Dec 86
n/imrrr
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PB87-132733
EPA/600/2-86/11]
December 1986
BOREHOLE SENSING METHODS FOR GROUND-WATER
INVESTIGATIONS AT HAZARDOUS WASTE SITES
by
Stephen W Wlieatcraft
Kendrick C Taylor
Water Resources Center
Djsert Research Institute
University of Nevada System
P O Box 602CO
Reno, Nv SO506
John W Mess
Thomas M Morns
Water Resources Cenler
Desert Research Institule
University of Ne\aila System
2505 Chandler Way, Suite 1
Las Vegas, \'v 80120
Cooperative Agreement No CIl 810052
Project Officer
Leslie G McMilhon
Ad\anceil Monitoring Systems DiMMon
Environmental Monitoring Sjstems Laboratory
LAS Vegas, Nevada 8911 I
ENVIRONMENT\L MONITORING SYSTEM^ L\HOR \TORY
orncc or RESE\ncii AND ni-:\'i:i OPMI:NT
LI S. ENVIRONMENTAL PROTICCTION ACF.NCY
LAS VEGAS, NTAADA 80!!-1
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TECHNICAL REPORT DATA
(Phas€ rcod Ins 17,ct,ons on :hc rc’i er ic beJorc corn plcrngl
1 REPORT NO 12
EPA/600/2—86/111 I
3 JiE I ENT AççL I
- 1
4 TITLE AND SUBTITIE
BOREHOLE SENSING METhODS FOR GROUND-WATER
IVt’ESTIGATIONS AT HAZARDOUS PASTE SITES
B REPORT DATE
Dece’,ber 1986
5 PERFORMI ’IG ORGANIZATION CODE
7 AUTHOR(S)
S.U. Wheatcraft, K.C. Taylor, J.W. Hess, T.tl. Norris
a PERFORMING ORGANIZATION REPORT NO
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Desert Research Institute
Un:versity of Nevada System
P.O. Box 60220, Reno, MV 89506
10 PROGRAM ELEMENT RU
C104
11 CONTRACT/GRANTNO
CR 810052
17 SPONSORING AGENCY NAME AND ADDRESS
Environmental Monito—ing Systems Laboratory, LV, 1V
Office of Research & Development
U.S. Environmental Protection Agency
Las Vecas, NV 89114
13 TYPE OF REPORT AND PERIOD COVERED
!rj c Port/Surr snary
14 SPONSORING AGENCY CODE
EPA 600/07
IS SUPPLEMENTARY NOTES
16 ARSTRACT
The complex nature of the ground-water contamination problem requires the collection
of extensive amounts of data in crder to understand the problem well onough to
recommend and execute the appropriate remedial action. As the complexity and
consequences of ground-water contamination increase, geo,hysical methods are
becoming a cost effective approach to providing answers to hydrogeologic questions
associated with ground—water contamination.
Geophysical methods ap licab1e to hazardous waste site investigations can be broken
into two categories: surface and subsurface methods. Surface methods offer the
advantages of relatively little capital investment at the site and rapid colletion
of data over a horizontal area. However, the intcrpretation is often ambiguous and
limited in vertical resolution. Subsurface methods can be used only to investigate
an area immediately around the borehole. However, subsurface methods provide
excellent information and resolution for vertical changes in measured parameters.
Also, a synergistic effect is achieved when certain logs are run togetior, potenti l1j
providing unambiguous interpretation of hydrogeologic parameters, especially in the
vertical dimension.
This report covers borehole geophysical methods and addresses problems of site
characterization, contaminant plume detection and monitoring of contaminant plumes.
17 KEY WORDS AND DOCUMENI ANALYSIS
DESCRIPTORS
b IDENTIFIERS/OPEN ENDED TERMS
COSATI I IsIdGro p
18 DISTRIBUTION STATEMENT
RELEASE TO PUDLIC
19 SECURITY CLASS fThlj I5epO I)
UNCLASSIFIED
21 NO OE PAGES
80
20 SECURITY CLASS (T!LJpQgc,
UNCLASSI FlED
22 PRICE
EPA Porn, 2220—1 (R.n 4—77) PREyOU €OT ON OI9 OLE L
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NOTICE
The information in this document has been f’jndr d wholly or in part by the Unite
States En ’ironrnental Protection Agency under cooperative Agreement #CRSiOO3 to Jie
Desert Research Institute, University of Nevada S stem It has been subject to the Age ieys
peer and administrative review, and it has been approved for pub ication as an EPA (locu-
ment Mention of trade names or commerical products does not constitute endorsement or
rt.commendation ior use
Ii
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ABSTRACT
The complex nature of (lie groun(l-water contaminat ion problem requires the collection
of extensive amounts of data in order to understand the problem vell enough to recommend
and execute the appropriate remedial action As the comp!e ity and consequences of groiiimd-
water contamination increase, geopysical methods are becomiiig a cost effective approach to
providing answers to hydrogeologic questions as ociated ithi grouud— ater contamination
Geophysical methods applicable to hazardous :isi e sii e invest l atious Ca ii be l)iokcn
into two categories surface and subsurface methods Surface methods offer the advantages of
relatively little capital in estment at the site and rapi’l col!ectioii of (lata over a horizontal
area llowe ’er, the interpretation is often ambiguous and limited iii vertical iesolutioiu Sub-
Sn rface nletho(ls can be used only to Investigate an area mm mcdi.itelv aron mud the l)oreluole
Ilowever, subsu rface methods provide excellent iiifortn.ution and resolution for vertical changes
in measured parameters Also, a synergistic effect is achmmevcd vlien certain logs are run
together, potcnLia !lv pros id rig unambiguous internretation of liydrogeologmc paraiimeters, espe-
cially in the vertical dimension
This report coveis borehole geophysical methods and addresses problems of site chuaiac-
terization, contaminant plume detection and monitoring of couitamimiaiii phi mes
florehiole tools and Intel pretat.ion nietlioilolog li:u e been ilc elopcc! primli il for tIme
eLroleum imidmisi ry The environijuen t of the ivpmcal hi17ardou \visi C ,ute is very d i (ferciit,
from the en viuoiiment encotu ii tered iii pet roleuu in c ploratuon. a id lie para meters of ut crest
are very different for the typical hazardous waste site i’u esi gal ion s a resiu It, most lioreluole
tools and virtually all in terpretat ion algorithms for borehole met hod’, are not directly appls a—
ble to h azardoims waste investigations The methods (le eloped by t lie pet rolemi m iiid ist ry
require modification, and in most cases, iicw mntrrpreation schi iucs irmust he developed
\Vc have developed an interpretation siritegy designed specificall) to estract data of
liyd rogeologic in terest from the suibsu rface The hore tm mole tools chosen for di is stral cg inch ide
natural gamma, gamma densit) , induction (apparent elect rical conduct i ity of the format loll),
tcleviewcr, and Lhermah horizontal flow mcter The data collected using these five tool’, are
combined so that hyd raulic conductivity, groii nd—water por elocitv, pore fi U id cond ucti tv
(a measure of total dissolved solids), and anisol ropy can he obtained These dat a are
ohtamned as a function of dept Ii, I hutis pro%’i(hmng .uhuishde detailed imihormation as input to comu—
tainmiian t Ira nsport mnodek
Lahora tory e perirnen is cond lid ed to (let erimi ujie the :u tumi •u( v of i lie thici mn.il groiiuiih—
va( er flow meter slucw thi at (lie flow meter Cami lie used io nimeasim re grnui muul—w,i icr it cs
dowii to (1 5 iiie ters per (lay ‘(‘lie resiths also slioa poor comm cli (ion hu I v. tin C\ pci mcii t s con—
diii ted iii (lie —tube cahibr,,t ion ,ind in (lie urge shill un’, a mu stilt c i ! lii ttor corrul,L—
(mu, i,hieomt. ’tic.ul wouk v.as coiuhmicted to .ihlow t lii grouiuiil—v..umi r flow mm 1 r to lii list d i’ bout
Iii
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Iaborttory cahbrat on and to show how the flow meter c n th’orettc ilIy he used to obtain
aquifer hydraulic conductivity, as well as flow rate and dircet on
2 V
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CONTENTS
Abstract . . iii
Figures . . . . . . viii
Tables . . . . . . . . . ix
Acknowledgments . . X
1. Introduction . . . . . . . . 1
Monitoring of Ground-water Quality at hazardous Waste Sites . .
The Problem or Contaminant Transport and Hazardous \Vaste
Site Characterization . . 2
Contaminant plume Detection . . . - .. . 3
Monitoring of Contaminant Plumes . . . .. . . 3
Purpose and Scope . . . . . . 3
Approah .. - . 4
2 Borehole Ceophysical Methods . 5
Traditional Use and Purpose of Borehole Geoph 3 sical ?vlcthods 5
Effects of the Borehole Envirenment . . .. . 6
Introduction . . . . . 6
Effects of drilling fluids . . . . .. . 6
Casing type 8
Summary . S
Traditional Borehole Logging Methods . . . . . . S
Electrical-magnetic logs . . 10
spontaneous potential . . . . . . . 10
single point resistance . . 12
induced current logging 12
Nuclear logs . . 12
gamma ray logging 16
active gamma (gamma-gamma) logging 16
neutron logs 16
Acoii’.tic logs 18
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Temperature logs
Televiewer -. - .- -
Multiple hole techniques -
Non I radii ional subsu rface sensing
3. Limitations of Borehole Methods for Ilydrogeologic lnvest:gations
Introduction
Equipment Limitations
Limitations of Interpretation Schemes
4. Borehole Logging Interpretation Strategy for Ilydrogeologists -
Introduction
Objectives . . -
Hazardous \Vaste Sfte lnvest gations
Site Charaiterization
Interpretation Strategy
Porosity . . -
Ilydraul ic conductivity and regional ground.water velocity
Hydraulic an isotropy
Lithology .
Cation exchange capacity
Pore fluid electrical conductivity ..
Computer Implementation .. .
Piirthcr Refinements
Effects of drilling disturbances - -
Tool response . . . . . . .
Improved electrical conductivity nioclel
Effects of contaminants - - - -
Conclusions - - . -
5 Use of Borehole Thermal Flow Meter for Determination of Croiiutl-waier
Velocity and hydraulic Conductivity .. . -
Introduction . -
Description and Theory of Operation -
Potential Prob’ems - - - -
Coals and Objectives -
Design and Construction of the Sand Box Flow Cliainlier
Summary of Experiments
Experimental Results
U I
t O
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I D
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21
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“C ’
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24
• 21
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27
29
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32
32
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33
33
33
35
35
36
-10
to
12
$2
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Experiments using the 5-cm end cap n s-cm well casing . . 45
Experiments using the pneumaic pacLer . . 47
Experiments using the fuzzy pacLer . . - 51
Instrument accuracy and repeatability -. . . . . 51
Theoretical Development ... . . .. 55
hitroduction - 55
Direct calculation of aquifer fluid velocity . . 55
Determinatior. of hydraulic conductiv my using the ttiernt l (low meter
. 60
Potential problems arid lirnitat ions 61
Summary and Conclusions ... . . . 62
Experimental worL velocity magnitude calibration 62
Experimental results directional accuracy . . - 62
Theoretical work 62
6 Summary and Concksions . 64
Introduction . ... . 61
Borehole Geoph ysical Methods . . ..
Limitations of Borehole Methods for llvdrogedogic hlaiardous Waste Invcs-
t i ,ations . 65
Borehole Logging Strategy for Ilydrogeo ogis s . . 66
Use of a Borehole Thermal flow Meter for Determination of Groii,id-W iter
Velocity and hydraulic Conducu ity . . 65
References . . 68
v ii
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FIGURES
2 1 Change of pore fluid in vicinity of borehole 7
22 Electrode placement for spontaneous potential log- 13
ging
2 3 Simulated geophysical logs. 11
2 1 Schematic of iiiduction toot operating 15
2 5 Schematic of formation density-compensated sonde. 17
4 1 InLerpretation strategy 25
4 2 The relationship between the velocity and the gra- 28
dient for an anisotropic aquifer
4 3 Lithology cross plot 30
5 1 Operating principle of the borehole thermal flow 37
meter
5 2 Diagram of the 5-em end cap and probe 38
53 Diagram of th ’ packers for the 10-cm borehole 30
54 Diagram of the ‘f-tube calibration chamber 41
5 5 Construction details of the sand box 43
5 6 Placement of the well casings in the sand ox ‘11
5 7 T-tube calibration of the 5-cm end Cal) 48
5 8 Sand box calibration of the 5-cm end cap 10
5 0 T-tuhe calibration of the pnci;matie packer 50
5 10 Sand box calibration of (lie pneumatic packer 5 2
5 11 T-tube calibration of he fuzzy packer 53
5 12 Sand box calibration of the fuzzy packer 51
5 13 Streamlines moving around and through a borehole 58
packer for different hydraulic conductivity ratios
5 1.1 Tangent streamline for determination of aquifer 50
fluid velocity and hydraulic conductivity
vt.i i
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TABLES
2 1 Borehole sensing techniques applicable to various 9
borehole en’s tronments
2 2 Borehole sensing methods II
S I Physical and hydraulic paTameters of the sand box 45
Summary of experiments ‘l b
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/tCKNOWLE DCMENTS
The authors isr, •-‘ thank the U S Enviro jmcataI rrotLLtton \genc\, Environmental
Monitoring Systems Laboratory for funding this project Mr I.esli’ McMillion provi(h d valu-
able advice and guidance as Project Olflcer Mr Charles Russell was very helpful with the
lahoratnry experiments Finally, ie wish to thank the rc ’ie i’rs, Dr Eileen l’octer of Wash-
ington State Unix ersit y, Dr Mark Stewart of the University of South Florida and l)r Aldo
Mazzella of U S EP Environmental Monitoring Setems Laboratory for their valuable corn-
rnents and sugg stioiis which imnprc -ed L t ie manuscript.
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SECTION 1
INTRODUCTION
MONITORING GROUND-WATER QUAliTY AT hAZARDOUS WASTE SITES
Monitoring of ground-water quality at. liaiartloiis waste site 5 is a sulije t of iutcn
interest in the U S Euviroiiinental Protection Agency (EPA) This iiiterest has been parked
by rcsii Its of several national surveys Lii at conclude tat groc nd—wa icr monitoring a both
Superfund and Res..urce Conservation and Eceo erv Act (ECI ‘ ) waste d’aposal sites f. lIs
short of accentability Problems identified during a EPA study of !2 UC’R sites (R Murphy,
EPA-\Vashingtoa DC, personal communication, 10S5) include
• \Vehls at about 50 percent of the sites are screened incorrectly Consequently, contain-
inant plumes that intersect the wells are not intercepted h the screens
o We1 s at JO pcrccat of the sites are itico, rtctT) placed, so that the contaiiuinani plume
does not. intersect the vcl! at. any depth
• For 10 percent of the sites, placement of monitoring well’, occu rrc(l h foi c the direction
of ground-water ilo.v had been determined
A more corn plete understanding of the site li) d rogeologuc setting O On Id in iuii ni IYt Sii( ii
problems Sulsu rface information is rerpi irc 1 to determ inc haiardouis vasI C Si e lird rogeologic
eonditio9s, locate contaruinnut plumes, and monitor itcs for leaks from disposal Iii ili t s
Borehole geophysics, in conjunction with surface geophysics and ot her geologic and Ii) drologic
techui ic ues, can aid in (leterrniuiing siLt hyd rogeologic parameters, partuc larI in t lie t Ii irtl
dimension Borehole geoph) sics can contribute aignifican Liv to our understanding of lii iologv,
porosity, and structure, ‘oncs of satui ratioi, ph siial a rid hieni cal chia racterustres of hi iiids,
and ground-water how speed and (lirection
TII I’ROTII EM OF CONTAMINANT TRANSPORT ANt) I1AZARI)OUJS WASTE
Ur,trl (lie early 1070’s, the science of liii rctg olog was primarily concerned itli ater
supply, vlu uchi is often refer red to as tire ‘groii nd-\d ater quarit it problem” i’li is problem is
sol ed by cleterm in in g the l)CloiPetric head or ‘ ater tabI, el ii ion d isu,ribii t tori iii rine and
space in response to stresses on the aquifer s ytem Aquifer tests to determine li dr iiihic
parameters have been iii routine use for more I ban 2t) years Numerical models hiM, prot ide
predictive models for cli anges iii head distribution are also used rout
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Concern over the contamination of groiind- %ater supplies has changed the primary
emphasis of hydrogeology from problems of ground-water quabty prohleiii to )roldem’, of
groii nd—water quality The gro’i nil- water qiLilit y problem C OliCerits the tr.i misport of soltites
(con 1am iii ants) in gron mmd waler To dci crmiii lie rates of con (a iii luau t I r,i napom I, gi on rid— w,mt er
velocity m list he known I lo cver, velocity (lain are norimiallv 01)1 sme(l by 111(111 cc l ii )ctliu ls
This is true for measurement of velocity in the fleld and cakulation of vclo iiy in model’,
Variations in ground- ’ater velocity owing to the heterogemicotis nature of (lie a(liiifer cause
dispersion of the contaminant Fhus the contaminant will have a elocity (lifleremit from the
average velocity of the groumid water i’hie (lifficuity of obta’ning accurate velocity mc lstmre-
men’s, as well as other difficulties, makes solving the groim nd- ater quality problem mitch
more difficult than solving the quantity problem lit addition, contaminated ground water at
hazardous aste sites is likel 3 to cntaiii numerous commtamiimrnts, making the proldenu consul-
c 1 ably more complex.
lJnderstandurmg the complc n,it nrc of the groitmid—water t ontanuiiiation prohk’mn \%Lll
enough to recommend and execute an appropriate remedial action requires that c\teiistve
amounts of data be collected. It us nearly impossible to colkct a leqiiste aiiioiimits of d,tta
ustng traditional hydrogeologic methods, consequcath , new technology is needed
Geophysical methods hate been widely used in oil and mineral exploration since the
1920’s Ilowever (hue to their cost and the rel ,itr’.e siti!p1icit of most previous grotiitd - ater
problems, gcoph nical methods have not commonly been used As the complexity and conse-
quences of groun(l-v:ater contamination increase, geophysics is becoming a more (‘OSI effective
approach to ans ering the li drologic questions associated ‘a ithu ground-water contamiriatmomi
A possible goal of a contaminant stud3 is to recoinmeiid rerne,l’al action that will cit her
clean up the contaminated grou nil ‘a ater or pre eat it from entering the biosphere IIo’aever,
before rem-ncdi.d ad iou can be taken, it. is necessary to u iulerst and i lte extent of tIn’ prohl& m
and the hiy(lrogeologlc conditions present at tire contaminated site There are mani ‘a a s to
approach this problem, hut from tile standpoint of RCRA, t1u pro lem can be di ’ uded into
three categories site characterization, contaminant plume detection, and mouuitom iuig of con-
lam in auit p In imi s
SITE C1lAEACTI;R (z, TroN
‘l’lre chtaracteri7at ion of a comi(aiilinaie(l (or poieiii p.1k’ roil? .umuliilmIv(l) site Coiisi’,ts pri—
mimarily of tletermnmning local hr drogologv ‘.inI wnt ‘Iiuiiitaiu t phiimiic li l r:lni I iou \Io t sue’, are
small compared tO (lie rcgiomi,il li I rogeologic M “teiii, amid the ret,iomial gu iuluent t’ami he’ super-
imposed on tire local sy ’ ,Lem to obtanim . gemicral l!o tl mrect ion ‘ t ru i uira g(’(-)logi( iiiforniai ion
can provide a pie, nrc of I lie geometry of the contaniiiiated aquifer Aquifer I e’ ts pros itl
information on the horizontal ii) dmaulic condiictm it and storat i it)’ of I hc aquifer The
storativ it)’ is tin necessary from i lie St and pot ii t of contain i ima ut Ira nspoi t, lu—ca use the liii
mass conser at ion eqliat on is usui.u liv solved as ‘ u’ad -‘state cqnmntioii ‘l’hie hi I r.i ii lie COil—
(hiicttvrt y d,rt a c ,Irtnunccl from aquifer t ’’,ts are of luiciited :ilui. ‘u-faunae of I hue — ,pii iii vari,ii,il—
ii> ’ of 1 nuufer properties, ‘a hticli greatly alk t the tramnspom I eorui.aiiiiii,iint’., Of primeumlar
ulnlCortance is the hi draiilic coumduucti it 3 ’ variaiioiu iii the ei ( i&;ul direst ion Aqutifu i tests are
of lim itch iu’,e for ert ic’.il arm itnomi’, hec,ttisc t hic produce iu l rair Inc coinliu-t i uiv va tue iii
aie integrated o er the vertical domain ‘i’e niuug of iuu’iividii,tl ‘ st rata can he dour il the ‘ t rata
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are liori ontally e ten -ive, but this is most oil en not (lie ca’ c in shallow, u necusolu! cited sedi-
ments In au autsotropic aquifer, the solute can be transp Jr(e(l in a direction different from
the gradient, thus aiiisotropv is a very imnortant parameter for contamlilalit studies Meas-
urement. cf the livdrauic conductivity tensor requires a rniiiimuuin of three observation a ells
The aquifer must he homogeneous over the area of these Ol)servation wells, which iS usually a
Irnor assliniption for shalla , tinrotisolidated sediments There is a clear need to (l& velol)
methods that will be useful in determining spatial variabilit and anisotropv for hydraulic
conductivity
CONTAMINANT PLUME I)ITECTION
Mapping the location and disluibiution of coiitniuiuii,unts iii gr .uiral waler (‘‘contanuinauit.
plume detect ion’’) is a iliuFicuihi problem because of I lie inau ccs ihi ii to the .ulLa ted environ-
ment Direct sampling methods ire Inn ited to monitoring vell ‘l’o adequiatel dci ermine con—
tantinant Concentration and plume migration, a large number of cosik nuonitorirug aells must
i)e drilled
MONITOrING CONT&MINAN r PLUMES
Cround—w,tte monitoring b re’ 1 uircd under RCII \ regulations at hazardous waste facili-
ties A successful monitoring net ork . ill (letect a leak fioin a permitted hiaiardous waste
facility or detect changes in ground-water quolit) in an aquifer near a hazardous waste sitC A
well-designed monitoring net ork should conform to a number of important criteria Zones
of high perneability should be locat u and spe ilically iruoiuitcred, because they are most
likely to contain the first arri a! vi a coiit.miuant The d iretional component of the
groli iid—wat er velocity will he t h u . iary coiisidema Lion in locating ‘up— a 11(1 (lown—gra(l en t
monitoring wells Often, nioriitoring of contaminant plumes is t houmgiut of iii terms of looking
for certain parameters 1 n this sense, a parameter is a property or chi2ractci istic of the ground
water or the aclim ifer itself hich Ii as been selected for mon ite :ng because it is md icati e of a
coiidmtiori or St ate of contamination The cliemia1, phiysic.tl, aiid ilectrical properties of the
ground water are imnportari t in deterinimi umig what ptraunct era should be monitored
PLJIfl’OSI; ANI) SCOPE
Cecphivsic. 1 l iiiethiods apphiculul’ to hii.urdoii, sii c iui i •. at ions ciii be brokeii
into two categories surface and subsurface nietluods Siirf,icc methods offer the ad’ alitage of
relat i ely liLle capital investment at (lie site (no borehole is r qiiired). and i ,quid olket ion ol
data o ur a hiorizoital area lka u’ver, Liut’ ututerprit it ion is often uuutiguiouua amid liiuiited iii
vertical rcsolui lion Suibsum rf,ice me! liocl require a boichuic •uul caii omik he use,! to iii es igute
an area un mc ’ i ely a roui n’ 1 t hue borehole I lo Cu er, tli ‘ l’ro ide e cclleui t in foriiiai ion on
vertical ( liii rige a in measui red par;u met cr5 A Iso, a sii it c of commi jdein n tan k gs ii potent ii I L
pros’ id uiiiaiui higuious interprei s on of I I) drogeologic dat a
‘I’lie tao pproaches corn plemnen I eucli oilier en well i’huc su hsuzrf.ire hid hiflila pros ide
I lie flCC2s ,u r ‘ in cal detail for a small area, auiil the suirfic iiuet hiods are ii,cd to est end this
detail lioruioii t ally h t a een borthoks
In this report, t he problems of site eluaracleri,.ut ion, couui uuiuuiar’ l)huuiule lete tion and
iuion utoi imig ol’ couitamninamit. phume arc :uldresstd using lou eliuk. gcophu ’ sie ‘hue o (rail gods
3
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of this project are to:
1 Determine which traditional and nontraditional borehole methods are best for addressing
the problems of site characterization and plume detection and monitoring
2. Develop a borehole logging interpretation strategy that can l)e used at hazardous waste
sites and that. is designed specifically to address the determination of liydrogeologic
parameters
3 Develop procedures for using the borehole thermal flow meter to obtain ground-water
vclocity and hydraulic conductivity data
Originally, this report was to include procedurea for all borehole tools recommended in
the borehole logging interpretation strategy Because of problems beyond the control of EPA
and the Desert Research Institute, Uriversity of Nevaua System (DEl), the only logging tool
available to fulls test was the borehole thermal !lo meter The pr’Ledures for using the rest
of the recommended suite of borehole logs with the interpretation strategy ‘ill be covered in
future reports, after the logging tools have become available and the strategy has been proven
to wor t , or has been refined as necessary
APPROACI I
Section 2 provides a description of the tra’hitional and nontraditional borehole logging
methods, including principles of c.peratlon, discussion of the properties that the tools measure,
and the parameters that the log analyst normally obtains from interpreting the logs
Emphasis is placed on the objectt es of traditional borehole logging More information is prc—
vided for the tools that will be singled out. as useful for the inftrpretation strategy outlined in
Section 4
Section 3 discusses the limitations of traditional borehole logging tech niques The di cus-
sion provides the reader with the reasons why it. is necessary to develop an entirely new and
different borehole hogg:ng strategy for h) drogeologic applications
Section .1 outlines the interpretation str.ttegy The at rategy tl . t is presented is oiil one
alternati e Actii l use of the str’itegv has not yet occurred, due to lack of equuipmcui t. The
strategy vill be refined and iml)roved based on the experiences of actual use
Section 5 presents the results of a detailed set of calibration iroceduires that were con-
ducte’l with the borehole thermal flow meter flecommendatious for its use are pres nted
Proc duires for the use of lie flow meter to (letermine aquifer hydraulic conduct ivitv are
developed The hydraulic conductivity puoced tires lia ’e not. been testc(l, an(l t heir verification
will be the subject of a future report
Section 6 presents the project summary conclusions . nd recornmendatioiis
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SECTION 2
BOREhOLE GEOPHYSICAL METhODS
TRADITIONAL USE AN!) PURPOSE OF BOREhOLE CEOPIIYSIOAL METhODS
A widely accepted (lefinition of borehole geophssics can be found iii l cys and MacCar)
(1971)
Geophysical %%elI logging, also called borehole geophysics, includes all techniques of
lowering sensing devices in a borehole and recording some ph’,sical paralileler that
may he interpreted in terms of (lie characteristics of the rocks, (lie fluids Co litnlne(l
in the rocks, and the construct iou of (lie well
This definition reflects the htstorical de elopinetit and use of borehole geophysical methods
The first known use of a borehole method was to measure (lie borehole fluid temperature
as a function of depth (Ilallock, I Sf)7). The first major horeliole method to be developed v as
in the area of borehole electrical resisti ity hr Schluinherger (l0O) The work was done in .in
oil field in France, and ic L borehole rnetlicxls %erc subsequently dc cloped in iesponse to
needs of the oil industry
The use of borehole geophysics b the water well (or groti tid-water SU 1)1)1)’) iiidtisi .y has
been limited h 3 a number of factors ‘ [ ‘he cost/benefit r tio of using borehole methods i i pure
grou r d— water sii pply invest igat ions Ii as trad it ond fly been ii ii favorable corn p red to iisun g
borehole logging in the field of petroleum e plorat ion Most water elk teu(l to he shiallo
relat i e to oil wells, and borehole methods hia e been de eloped for deep well nph)hlcat ion Iii
the oil industry, borehole methods have been used to help locate new wells to ma\iuniie plo—
du ct reco cry The criteria for locating water w.lls are more often related to ctiltii ral neces-
sitY, such as locating the ell near population centers, an(I locating diallo v water son rces to
minimize pumping costs
In recent rears, considerable attention has been focused on (lie problems of groun(l-\ uter
contamin ition, especially at hazardous ‘ aate sites The aiiioniit of inone l)eing spent on the
clean tip of hiazartlotis v aste sites is ‘ ery large, cspcciiIl eoiiitulr((l to ti u I lion ii groiuiiul—
ater siirplv Investigaluons As a result, borehole gcopli su il methods nrc no longer (oii-
sidered to be rekti el cost lv Tb is has cret ted a imeed to (levelol) borehole too6 111(1 mmii erpre—
tation strategies t mat can be used in grou uid-i ater con t arm in tion studies
Some c,f the basic rea ns for doing geopli scal eIl lo giuig umu tide
5
-------
To allow visual Interpretation and compai ison at the well site
2 Immediate decisions can he made rcgar(liiig screening intervals
3 Well logging is superior to and less expensive than (Oil tini bus coring (a ii alt erii:tt 1% e s iv
to obtain su 1)511 rface in form at.ion)
‘I Well logging provides iaformation on lithologic boundaries
A well log itself is of limited use without apl)lviiig some sort of ililerpretalion to I lie raw
data Nearly all log inte’pretatioiu in the petroleum industry u (lesignc(l for open hole welL,
I he logging dofle prior to installation of casing
The objectives of open hole log iiiterprelat .ion include
I. Remove drilling, mud and borehole effects from loggulig data
2 Determine rock properties, such as porosity, lithologic traps, and absolute, relative and
effective permeability
3 Determine formation uluiid properties such as oil and gas specific gravity, lisdrostatic
pressure, fluid sat iiration distril)ution and tenuperat ure
4 Obtain information on the formation factor which leads to determination of porosut’,
permeability and pore fluid conductivity
EFFECTS OF TI E UORE!IOI.E ENVIRONMENT
Introduction
The methods of drilling and coml)let loll of a borehole will affect the types of geopli) icil
logs that can he ruin and the m l erfiretatiolls of the data from I hem if the hole is in unconsoli-
dated sediments, the typical casc iii the vicinity of nianiy hu ,uzardouis waste sites, tIme matrix .s
friable and collapses easily One way of coping \% it Ii tli is condition is by adding various
materials to the drilling fluid, usually the weghut of (lie column of (Irilling Ii uiid is greater than
tli e pressure of flu ids in t he ma tris rock ‘lii is ach eves mccli an ic i I ath bility of tlu e ho t e b
applying hack pressure to the formation, I hat Is, sI ability i ccli eyed at the Cost of cai’ ’uug i lie
drilling fluid to enter (lie pores of the formation Tb iS liii mnied lately C lu,i nuges thu e l)luys lca I p
pertics of the formation near (lie borehole, which is highly undesirable if the purpose of mak-
ing the hole is to ascertain the phsical properties of the formation and/or its fluid contents
The type of material used to case a hole us imporlatit Typical materials include steel,
alum in urn, PVC or Other plastics, and Teflon \Vluet her the borehole is air or liquid lulled n ill
also ailed tIme geopli suu al iuietlioil ’, available fur use iii lucuii
Effects cf’ drilling fluids
After t lie hole is di dIed, the logging tools are lowered iiitô I lie drill bole to make meas—
iireuneiuts (hat arc liopeftilly representative of the forniat ion Such obst rvations nuuust be
adjusted for t lie changes winch have been cic’:uted iii (lie vicinity of (lie hole h I hue drilling
operation \s an ihluust ration, consider I ’giire 2 1 The elect ric.’l resist lvii’, (a very signulcant
ii il icator of tIe type and amount of hiqiu ids in the pore spacc) chi ingcs consider,uh>l’,’ as a fuii’c—
tion of radial distance fronu the a\ns of I he drill lic,le The diilhuuig fluid lu,i ciiteicd into the
form ation since it is for safely reasons, at. a shuglu I l v hi ghuer pressui ru’ I han’ (lie niul bui’ii t orn ia—
tion pressure Some f the materu:il in suspension Ii is been filtered out it i lu suirfire of the
sidewall to form a rnud ’ake The rest of the drilling lhiii h, a hiicli is cihled tli flltr ie,
-------
FTt;URI: 2. I. C’rnnge of Pore lint ‘ I i it V Ic in t i v of linre lto 1 e
BORE HOLE
IMPERMEABLE BED
-e
/
I
St.
—
IMPERMEABLE BED
7
-------
continues penetrating into the formation, the e ient of the format ion so penetrated is called
the invaded zone. I’li? filtrate saries throughout the ins :“led zone to the percentage of pore
space that is occii pied If the filtrate occu pies all of the pore space, t hen Ui at portion of (lie
invaded zone is termed the flushed zone, the remaining portion of the in ’ ad t1 zone is called
the traitsitton zone Note that the electrical rt cistivii y of I lie miiil is intcriiie(li,ite in value
hetsseen the resistivity of the niiulcake anti the resist is ity of the hilt rate
The size of the flushed zone or the invaded zone will chaiige over time ‘Flierefore, it is
importast to correct the geophi)sical and geochemical observations for the conditions which
existed at tl’e time of data collection This evaluation is especiill% iniportaiit in the monitor-
ing phase of hazardous ssastc site operations because teinpotal changes in borehole logs might
he mistakeny attributed to contamination instead of borehole ens ironuieni. changes
Casing type
The usual material used for casing a hole is 5 i c cl dii e to its st ren gi Ii, lio;s ever, for shi.i I—
low holes, those less than a few hutid red meters, other tubing siicii as PVC, Tehlon, or oilier
plastics can be used Tb is is especially appropriate to inoii it oriiig operatioiis iii wli icli t he hole
is to he used repeatedly over time Many of the logging techniques cannot he applied in a hole
cased with metal
Summary
Ti Ide 2 I sliosss t lie s ariouis geophysical met lioils svhi cli are appi opriate to i he wet or
dry and cased or uneased hole ‘Flits is not meant to he an exhaustive presentatioii, simply
illustratis e of die constraints of the ho’e coi”l’t’oiis on the geoph sic-al iiiforniat ion that can
be obtained from the hole Note that the radiation tee liii iques are t lie most versat ic-, bc-ui g
meaniiigfnl in an open hole or a cased hole When escd iii a taseul hole, ni erpret ito H is easier
and bet ter if t lie same log has heen mu in the same hide belore it was cased The induction
techniques can be ii cd ii place of contact r istivit ’ techniques for the (3 l1lcal plastic-cased
holes found in hazardous ssaste bite ia;estigaiions Cochieniual methods are sometimes used
in liquid-fl ll?d holes to sample t lie -am h tent hiqu i lls If inform ation on dept ii dependence is
sought. then much more conip’ieated instrumentation is usually required
TRADITIONAL BOREI I OLE LOGGING NI ETI IODS
Descriptions of the various borehole techniques ,siud eqiiu -ment are gis cii below The
d escri l1tio are rat her short because i lie equ upmen t and iii terlPret at ion tec lin iquies are open
ii ole, a rid t li eir application in hiaza rdomis waste in cesi ugat otis is liiii ii utl Lnoiigh ulet a il is l)T
oleul to set. t li stage for t lie d Iscuussion of :niit at ions in Section 3 Nu ineroiis references are
available that provide detaule I iiist ructious on tie use of borehole hogging tools and the
interpretation of open hole logging data See for esninple S hluinlucrger (I 972) Asqii it ii
(1082), llilchiie (1982) Dresser Atlas (10821 and keys and \licC.iry (1971) lii Sect iou t, an
interpretation scheme is developed speciflc.dk for applic ii ion to ground-ss ater irs estigat Gu s
at ii azardouis u as ic sites, a urd the borehole met boiL uisc-fui I foi tli is piilu at iou :rc il iseuisseui
01(1 iv id uialh:,
Borehole methods fall into us e major ca °gories acoustical, elect r unagnaic, nuclear,
flow and d imneusuon and t hierma I N lajor a -phmc.it ions of t hi e se u ccliii iqiu es mi dde lit liologic
correlation, hithuology, rock density, fractu ns, porosit) , hieri luethilit y , loss, scat er les el, ss at er
-------
TABLE 2.1
BOREHOLE SENSING TECHNIQUES APPLICABLE TO VARIOUS BOREHOLE ENVIRONMENTS
Logging Techniques
Single Woll
Cioss Borehole
In Situ
PVC s
C od
Stool
Cased
Uncaood
PVC •
Casod
Stool
Caacd
Uncasod
PVC •
Caaod
Stool
Cased
Uncc od
WET
DRY
WET
DRY
WET
DRY
WET
DRY
WET
DRY
WET
DRY
WET
DRY
WET
DRY
WET
DRY
ACOUSTIC
0
0
ELECTRIC
0
0
‘
0
0
0
INDUCTION
C
9
0
0
0
0
0
e
NUCLEAR
0
0
0
0
0
0
FLOW
0
0
0
0
0
0
0
0
0
TEMPERATURE
C
C
0
0
9
0
CHEMICAL
0
0
0
0
0
0
Note, PVC Is shown but other plastic casings (le, teflon) behave similarly.
-------
quality tern peratiire gradient an(I hole diameter Ta blc 2 2 i a stiiii iii,ti y of borehole olijec—
tives and the methods used to achieve them
!lardw are for borehole geophysical logging consists of siinil:ir basic components for all
the (llhlercnt. tools, conststing of sensor, signal conditioners, and .i recorder The s nsor or
sonde receives power and transmits the signal to the surface through a coriductin’g cable,
which also serves to position the tool in the liok by means ol a winch
Electronic controls at t!ie surface regulate logging speed and direction po er to the clownliole
electronics, signal cond itioti ing, and recorder respoises
Two types of signal cc n(hitloning aid iccorder responses are available analog and digital
? lost systems that are equipped with digital processing 511(1 storage are also equipped with
analog recording for pur oses of backup and ev minatioii of the dat:i during logging The
return signal from the probe is a function of litlotogic, fluid, and borehole l)ar.lmele ’ an(l is
recorded and later analyzed with a computer
Electrical-magnetic logs
Electric and magnetic logs provide information about hitliologv, saturation, fract nrc loca-
tion, fluid movement in t he borehole and fluid coiiductivity ‘J’hcre are mali)’ ty 1 )cs of resis-
tivity and resistance tools in use
Electric logs are a record of electrical potentials and resistivities These logs can gen-
erally be rim only in uncased holes that are filled with a co;idtiet ing Il itid There are ni iiiv
types of electric logs which can be run in a borehole, the choice of ‘h C II is dependent ii pon
the i urpc e of the survey Some lectric logs make use of t lie tiatmi ral electrical currents that
exist under certain conditions Most common is the spontaneous-potential (SI’), ‘. hitch is
described below
Other electric logs induce a current to flow in the fortitation for the purpose of recording
resistance ar’i/or resismi it)’ There are numerous types of lb logs, iiicliidirig single porn’
and diljcrcr.tial resistance, short normal, long normal, lateral, niicrolog, inieroloctis log anc
the guard or lateral resistivity log Each of these logs has a spccilIc apphicatioa, depcnding
upon the hitliobogy, depth of drilling mud in asion, and area of interest wit Ii iii t lie borehole It
is not necessary to run all of these electric logs to det ermine variations iii hithobogy, aqii icr
locations, and relative conductivit es of porous media fluid’,
spontaneous potential—
The SP logs measure t lie smalt dihlerences in nat ural potentials t list develop iii t lie
borehioh’ as a result of hi iiid niovemen t situ electrical pot iii tm.ik uhiie to borehole liii id inigra—
tion at hitliologic contacts SF’ logs can be used t.o (lelmneale fault zones and water producing
units iii the borehole
Keys and MacCars (11)71) point. out that the most import nut sonr e of SF’ us (Inc to the
electrochenruical elect rornot is e force (cmiii) prod iuced at the iii tei I see het,wciui chussiiiimlar imi.it en—
abs iii t lie huorehiole SI’ may ,ihso be genucr.utid iii ioiuis of g.iiuiuuug or losuuig ivit r ‘l’hie ‘ I ’ log
can a so be ii cd to dehiuicate rcl,it ive hydraulic eoiudiu tu itic l,.isel on I lie kuio ledge ot
boreho e Iluid potentials \\‘hien the seater wit hun au .iqiiilur iiiiil h uuiorc coiidiuct ive thin t lie
borehole water, (lie cm i generated from the strea m iii ug 1101 cii liii or from t lie jui net loll of dus-
sinnil ir miteruals causes a cuurrcuit, to lb’s froiuu lie hout ho 1 , into thi t huh \ —, the SI’ ek(—
tro(le moses ujiw irih, it si’fl’a’, a (lecrelsulig poliuuimil bni iii,, the I iiruuiit ftosss purillil to tin
1(1
-------
F t !)lO 2 2
I3OREIIOLE SENSING METIIOI)S
OBJECTIVE I BOUE1 lflI,E Ml ?’ ! ’ ! l()DS
Location of Zones
of Saturation
Flectric Log (fuUy saturated)
Temperature log
Neutron log
Gamma-gamma log
Physical and Chemical
Characteristics of
Fluids
Electric log
Temperature log
Fluid conductivity log
Spontancoii potential log
Specilic ion electrodes
Fiber optics
D 0 Eli, pit probes
Formation resisti itv log
Induced l)Ol,trllatiOn log
Nattii al gain ma log
Spectra! gamma log
Therm a! micu troim log
Cross borehole radar
Cross borehole sbc.mr
Resistiiicc log
Acoustic -
‘l’ranstt lime log
Acoustic -
\Vaveforiii log
Nemi I ron log
Induct on log
Spoil tan coils potent ii! log
Flow meter
‘l’r acer
I)ilTcreim tial teniperatim re log
\!lIer level
Strat igraplmv
and Porosity
Flow and Direction
11
-------
well bore This relationship woi’ld he reversed in the case of good iiality waler with in an
aquifer unit and one would see a positive SF response opposite the aquifer unit ‘Fhiis a nega-
tive or positive response on the SF log can be used to infer relative formation water qualities
if the borehole fluid conduetivities are known
The electrcde placement for SF logging is shown in Fig ure 2 2, one clectiode is embed-
ded in the surface material and the oth°r is lower ti down the hole l’igure 2 3 is a suite of
simulated geophysical logs including SF indicating their response to duffement luydrostrati-
graphic units A more detailed discussion of SF logging methods can lie found in lId-
cli ‘e( I 982)
single point resistance--
Single point resistance logs measure the resistance to current how of the borehole humid
and naterial The logs are usel ul iii geologic correlatio ns because of their uiui ique response to
changes of lithology Fractures or zones of weakness can he mapped suth resistance logs, iii
addition to changes in borehole fluuiil condiictivutirs The resistance log can he used as a sensu-
tr e caliper log and as a water quality indicator. The SI ’ and resistance logs are usually inter-
preted as a unit in any one borehole
induced-current logging--
The met hods prey ioiusly descrihed has e reqiiireil a coiid u etive II Li ud because t Ii C LU rreii t
llosss omic into the formation directly from the electrodes If it is necessary to siinvey a hole
which contains a non-eo’iductive medium such as anr or hsdrocarhon, electrical iiivestigations
can he carried out 1 n inducing currents in the formations surrounding the borehole This
technique is called induction logging, and the theory is analogous to induction techniques iise’l
on the an rfaee of the earth This method cqa also he used in non—met ,Lhlic cased holes
Figure 2 I shows a diagram or a conceptual induction tool One coil is used for trniisirmit_
ting, the other for receiving An a!ternating enrreiit of constant intensity is passed through
die transmitter coil at a very high frequency This electric t ield lisa an associated magnetic
field s hicli, in turn, induces v ctruc currents in the formatio?s ‘h’lie phenomenon is linear for
practical ranges of current levels, so the iiirliircd cii rrcii t- us ill be of the same frequiciuey ,‘, t lie
source current, hut different in intensity and phase Asociatcd with the ground currents
flowing around the hole is a magnetic field, ssliicli induces current to flow in the receiver coil
Of course, the magnetic Field associate(l with the transmitter coil also induces curreit to flow
in the receiver coil, hut this can be filtered on t h catilir,ition prou’euhuires iii an ideal known
environmneiit, e g , air lii actual practice, the i’udiictioii tool ill have more ihi,uui tsso coils,
usually sm or cven more Add it ion .il coils provide seh’et is o Ice iisiii g of i lie Ira iisuuu iii cl sigii il
so that the measureauent us weighted away from the hors hole envimnuinuciut aiiul its effects
Figure 2 3 includes a hypothetical inverse induction log
Nuclear logs
Nuclear logs measure railiai ion emitted frorui the n oe L us of au nioni .uuul li.ive a ul ist iiict
advantage over most other geophy sieal logs in that i Iie can dens e iiiformui atioui froni cased or
uneased holes that are filled with aimy type of fluid ‘l’lie most coiruuioii nuclear logs arc
natural gamma, gamiuia ganiiiia, anrl neutron-neutron lhie nrinisry fuiiici ion of these logs is
to deteriiiune variations iii lithiology deiisuty, nuid iiiousi nrc coii teat or porosul witliiii t lie
borehole materials
12
-------
r Mud Level
9
9MU
FIGURE 2.2. Electrode Placement fot Spontaneoti, Potciit In I
Loggf ng.
I 3
-------
FT(.UIU: 2. •3. s I aii tI (COP 1 1Y S I dl Logs.
SIMULATED GEOPHYSICAL LOGS
-------
Line of magnetic field
of induced current
Line of magnetic
field of transmitter
FiCL’k 2.4.
Sciie .tic of induct ion Tool Uerat I n . The irans’iit or
an(. ceivcr Coi I ni e in a orL;IoI C IJICI c s Lie ln
ducen Ciii rent s in tee ariii.
(e)
/
/
/
(d)
Induced
Current
(b)
\
\
(a)
/
,,
N
Is
-------
gamma-ray logging--
This is a passive technique which uses a scintillation counter to inc.usure the natural
gamma radiation emitted by the materials in the rucuuuity of the sonde Because the gamma
r.tv emission is statistical in nature, it is approrruate to aver ige the counts over tunic in order
to obtain a stable value The duration for a eraging depends u .on the level of raduoact i uty,
lower levels requiring longer times A few seconds are iuorin uIlr a lequinte iii pr Lice l)uue to
Ii is averaging, any anomaly will he sh i.tcd in the direction ii hid u the tool Is moviiig
Cam ma—ray logging can he performed in a cased hole II ,ib olui te vi luics are (Ii ’ irt ’(i, then
corrections should be made for the dcn ..ty of the mud, the ‘hianieter of the hole, casing pro-
perties etc
Because ra(hioactuve elements tend to Concentrate in shu .tleS and clays, the gainmu-ra) log
IS liSli .111) in t erpret eu to indicate the sh dc content iii stsiiuuie,i i an fornia Lions A l’ ic i I pas-
sive galuima-ray log is sIuo i n in Figure 2 3
active gamma (gamma-gamma) logging--
In gamma-gamma logging the scintillation counter is packaged tht,o a sonde with a
radioactive source, as shown diagrammatucall in Figure 2 5(a The sonde is pushed against
the sidewall to reduce or eliminate die effects of the niud Tue source emits medium-energy
gamma-rays which pass into tIme lorniation where they collide t itiu elect rout-, and are scat-
tered Some of these scattered gamma-rays are di ecteul by LIm( scintillation counter located at
a fixed (listauce from the source Thus, the act e ganima-ra technique (lepeilds on the eke-
trout density of the formatton Since tim us is direct ; related to the bulk density of the forma-
tion, this technique is usually called the formation density log.
To circumvent the problem of correcting fo the mmmdc ike, a sonde with one radioaclu ’ ,c
source arid t o detectors can be used Assuming that the mudcake condul ions are the s.ume at
both thu detectors, which are at d ifferemi t d matances from t lie mi rce, t lien t lie d ifferemuce
between the readings siiI be duicctlv related to time forniat ion electron density and, luence, the
bulk density The dufterence is independent of both die muidcake density and its thickness if
bot:i dctector encounter the sautic conditions Such a somidi-, lma iiig two (lcte:tors and one
son rce, us depicted in Figure 2 5(b) Tli m ’ s is calkd Ilic Form at ion l)ensit y Coin n nsat ed (FI)C)
tool
neutron logs--
‘ [ ‘he configu rat ion of the proh)e in neuil run osguuig is oriented so that t lie tool responds
prima rit to a function of l:yd rogen content iii he borehole en uronmeui t Neim tron energy is
modified by elastic collisions uthu borehole elements and the eFectivummess of these energ
motlerators us a primary lactor in neutron logging ‘Flue un.iss of the n uicleuis of a Ii ’. drcugcn
atom has approxiumi at ely time same mass as I lie nemut ron, so a colim’sion of a imeuit ron mdi a
h d rogeu atom causes die neutron max u mmmi cnt-rg loss
Conseqmitiut 1%’, the energy of tIme neuut roll re ’ spon e i iii erprel ed for mmuoist IIFt• 1 oritimml iii I lie
ii iisatmi rated zone of mIte borehole auu(l t lie tot .ui porosity ! lo t hue water tilde Neui I ron logs
can hiow t he Ioc,u I mon of porous .uqmi ii mmmi ‘t perehitil t at yr tahule’s, amid groum mmd—t’ at er
confining zones, suithi as clay layers
-------
Mudcake (a) (b)
FIGURE 2.5 Schematic of Formation Density Compensated Sonde (b); Original Design
shown in (a).
-------
Acoustic logs
The ability o a rock to transmit acoustical \ aves is a measurable rock property that is
useful in determining related properties of interest such as pcrosity and fracturing The most
commonly used acoustical wave for these studies is a pressure wave that is generat ’d by a
source in the borehole In the simplest of tool designs this vave is detected at a receiver
located in the borehole which is a short but constant distance from the source Although
many travel paths occur, the instrument is set to record only the wave which is refracted
through the formation Currently, instrumentation is available to measure both seismic velo-
city and the full seismic waveform
Seismic velocity, as measured by borehole methods, is the speed at which a vertical trav-
eling pressure wave propagates and is dependent on the el istic propertlis of the formation
Since rock material and fluids have such vastly diffcreiit elastic properties, the presence of
fluids will greatly effect the velocity. \Vylhie(195fl) derived an empirical rcl it monship between
porosity and velocity
I — n I—n
V. p + Vm
v , hem e
V, = measured acoustic velocity
V = matri< acoustic velocity
V 1 = pare fluid acoustic velocity
n = porosity
The matrix velocity (V.,, ) is the acoustic velocity with iii tla matrix of the fo , niation
Since this is nearly a const,int for most common earth materials, its value can be assumed
Pore fluid velocity (V 1 ) can also be assumed because it is nearly constant for water Hence
using this equation, the porosity can he determined The nd’ antage of using an acoustic tool
t measure porosity instead of a tool with a radioactive source is the logistical simplification
of eliminating the radioactive source
Acoustic amplitude can also be recorded by some eqiiipmnemmt ‘rhis equipment normally
records the full pressure waveform Discomi I inuit cs in the format ion such as fi tcI ures, will
influence the waveform ainlilitude Although it is not cii rrcnth possible to quantify fracture
patterns using the waveform amplitude, at least an mndical 10k of fracture occurrence c.mn he
obtained.
Acoustic logging is commonly (lone ifl an open hole ‘lime presemice of a easing creites
another travel path for the seismic energy niud the iiistriimentat ion mmi.,st be able to distin-
guish the arrival through the casing from the arrival through I lie formatioa
Variations in borehole diameter will significantly effect both velocity and amplitude
measurements hence most tools employ two transmitters, one located abo,’e and one below a
pair of receivers This geometry allows processing of ihie signals so as to nuiiimnii?e errors due
to variations in the borehole diameter
18
-------
Temperature logs
The temperature in a shallow we [ l can easily be measured using an appropriate theriiiis-
tor This temperature may be used to correct otlici cl)’,crved data. sicli is the condiictiviiy
log and the resistivity log. The tempenlure log can also he used to :ndicate borehole iiitervnls
that are producing or accepting fluiids This may be helpful in locating zones for more det,iiled
flow iiieasi!reriien ts with a borehole therm at lIow meter ( discussed iii Se tioii 5)
Televiewer
This tool is simply a television camera which is used to look at the interior of the
borehole and/or well casing It can delineate and correlate fractures if used : ior to e’isiiig
installation For wells in which there is no easing informatiniu , the eluviewer us useful for
inspecting perforations or slotting and determining their frequieuiey and orientation Slotting
information is necessary to properly tcse die thermal luoi izental how meter discussed in a later
section
Multiple hole techniques
Multiple hole techniques reqii ire se cml ho’ s for iiuiplenientation Seismic met hods are
commonly used between borehuoles A seismic source is pliceil in one hole, mid seismic signals
are received in one or more odin boreholes (Calperin 1971) fly placing source and rerei% ers
at different depths in different holes, rcmplex ihnee di’nensionnl interpretations are possible
Borehole-to-borehole iadar is another commonl used mull tile hole ineihiod Operat ion-
ally, this method is sunilar to the rut kink hole seismic techinx 1 ues, with t lie sebul ic source
and receiver being replaced by an elec-croruagnetic transmitter uid receiver
Nontraditional subsurface sensing
In addition to the ti-adit ional locging methods ties eloped by the petroleii in aunt inner LI
industries, there are a number of sensing techniques t lint can potent udlly provide al’iablc
information for hazardous waste site in estigations Non-triuditioiual techniques ujiclude geo-
chemical, thermal, mo’nure and vapoc sensing methods Of partictular interest is (lie ground-
water flow meter which senses groii ncE—%¼ ater tlow Ii)’ iiidiiceil t lu’rinal piik Tli is iuisi ru nieuit
is discussed in detail in Sectioii S c-nsors 1o rnan of these niethiods can be left in sit ii lou-
continuous monitoring with time Table 2 2 presents a list of methods applicable to measuring
different properties of i’iterest in haza;dous scaste sue unvestig-mtiouus and monitoiing
/n situ methods may prove to be particularly useful for the problem of contaminant
plume monitoring Long term mon itcsing of borehole parimeters will provide informnt mi on
t he ariance of die monitored parameters (from a stochi ast ic point of iew) a id bug t cnn
trends of increase v decrease of the parameters For many of the i ii su(ti methods, little addi-
tioiial cost is uncu 1 rred to collect the data, once the inst rimnicntation is in place
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SECTION 3
LIMITATIONS OF BOREHOLE METhODS FOR HYDROGEOLOGIC
INVESTIGAT!ONS
INTRODUCTION
From the information provided ii Section 2, it should he evident tlint consi(lerab!e p 100—
lems are encountered wher trying to apply e\istti ig borehole methods to the hydrogeotogic
investigations at hazardous waste sites The prol)lcrns arise primarily from two considera-
tions
I The typical environment, iii which borehole methods are cc,mrnouly used in the
petroleum industry is very different than the environment that commonly c ists at
hazardous asLe sites
2 The petroleum industry obtains information front the boicliole logs that is quite different
from the information sought by the Its drogeologist for hazardous waste sites.
I QtJIPMt NT LIMITATIONS
The design corisulerat oiis for horehiole loggiiig c(IuipTiieiil lt,ive pm iiiiirily been et l the
petroleum and mineral industry and are a direct iesiilt of the envirorirneilt thi”t, I he IIiPment
must Iii at LlOfl in It is useful to contrast and compare thc ‘‘typical environment.” for .t
etrolcum well and a s cl i installed for rnonitorir g a liazam dons waste site
Oil vehl ate nearly al ays ‘I eep (l d reds to t how,a nd of mdci ‘) I oggmiig is done
immediately upon hole completion and often before cOiiiI)ldtlofl, the hole is logged to aid in
determining how much furt her to drill Once (lie hole is logged iipoii comriplet ion, it i selilom
logged again Most oil wells are at least 30 cmii in dia net cm ‘ Plo. hole is Ii lied wit Ii iii mid d tiring
logging, and the mud has in Ii lt,rated into the format ion
There arc a n ii mn 1 er of common aspects regard tug the design ol borehole equ ipmucu t for
liese en v imomi men ts The dow nhiolc son(les in iist be able to it listand Ii igh I re su re an d ti in—
pcrat tire beca use of (lie dept ii Several logging tools arc (oni mitonly inst . lkd iii omic long soi
Tb us u.s (lone for t v c. reasons the large depthia Gupled with the desire to obt .iiii a iii tilt i-log
suite, amid the need to obt iiii multi—log suites that. ( ifl he i( ( ,.r.iielv correlated for ilept hi ‘ ci i I
respect to each other Miii i—log son,lcs can lie as nit u i Ii :is 5 iii in kiigt Ii l’or .t Spun—ut
borehole, a 5-rn long sonde can he considered to he essentially a point Many of the ln. giiig
tools will mdv work in an open hinle ‘l’aldc 2 I snimniii,tiiic ’ the kinds of cnvironiuirni- thu
20
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various types of logging tools can be used in
The typical borehote that. exists at (or around) hazardous waste sites is shallow (prob-
ably less that 100 m and typically about 30 m), narrow diameter (5 cm) an(i cased, usually
with PVC, teflon, or some other plastic. None of the borehole tools that h, ve been designed
for petroleum well logging are usable in such an environment Although a 5 in sonde would
lit in a 30 m borehole, its upper most tools would miss fogging the bottom portion of t’ie
borehole. Unless the hole has not been cased, none of the open hole tools such as the electric
logging toots, can be used If the tools could be used, they would be over-designed for tern-
perature and pressure requirements, however the hazardous waste site ground water may COfl-
tam chemicaT for which tue sonde was not designed to siLhsLand
LEMITATIONS OF INTERPRETATION Sd IEMES
Most of the interpretation schemes that have been developed ha e been for ripen hole
logging The emphasis is on eliminating borehole mud nd irnid filtrate effects from the data,
and trying to determine formation contacts and other parameters that are useful to the
petroleum reservoir ertg neer The parameters that are of interest to the petroleum undustr)
are discussed in Section 2 The parameters that are of irutt’rest to the hydrogeologist are dcl-
ineated in Section 4, along with an interpretation strategy to obtain them
21
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SECTION
BOREHOLE LOGGING INTERPRETATION STRATEGY FOR
IIYDROGEOLO’ISTS
IN TR 0 D U CTIO N
The oil and mineral industries have been collecting .in(l in(erpretiiig borehole logging
data for man)’ years The interpretation strategies that have been developed are nat’irally
oriented towaids solving problems and answering questions t hat are of interest to these dis-
ciplines Borehole logging data are otentiall’, of great value to hi’.drogeologists for evaluating
hazardous waste sites llowe er, new interpretation strategies must be developed that are
designed to provide qIiantmtati e information on the formation parameters that arc of hi3 dro-
geolog . iterest
Th re is some overlap in the interests of the hid rogeologist and those of the oil or
mineral geolglst However, the collection and interpretation of logging data rcquiiics a com-
plete re-t bin king in order 10 masirnize the information t hunt is useful for th 1 e St tidy and predic-
tion of contaminant transport in aquifers
The vertical variation in hydraulic parameteN vithrii an a( 1 ui lfer is recogui ized to he of
primary iruipot tanic iii detcriniuiing the f.itc amid transport of couit uiuiiuuiiit. iii ginuiuiul— citer
systems Traditionally, the process of hi d rod) nam mc d msj)c r ion I as been t lion gI l I. to be the
domi aiut. process causing contamiuiant. nhi\ing Macro-scale heterogeneity and vertical
stratification mnducc large variations in the advect: e (low rate of the groui tud water ‘I’Iiis l) o-
cess has been termed macroscopic d spersion (Schwartz, 1077, Suuiit hi and Schwart i, 1080), and
it is the dominant mechanism controlling contaminant ini ing an(h Iransl)ort in mail)’ aquifers
l.a rgely because of macros( opuc (I m persmon t radii uoii.I I tta liii IqIICS of \‘(rt lea I liii egi a lio n
(Dear, 1979, Chapter 5) to deri e two-dimensional ert i’. hIs —a eraged gron nul-wat er Ihoss’ equa-
tions are inadequate to (lescrihe contaminant transport in aqtu ifers \ht hiotighu ml m important
to account for vertical variatir’n in h (Irauhic parameters, here ha’, been little elfort to
develop adec 1 uiatc horehio t e raethiods that w ou 1(1 pros ale such part meters \quu uler paranieturs
that are important for cont amilian I transport si mites include lit luology, effective aiid total
porosity, tensor hydraulic cond uct is it , ft nid dcx mt , cat ion e ch 1 ligc en p I y, aquifer
dispersivity and total organic carbon
In a general sense, geophi sical methods apphicalile to a in’ ulous ast e site iui 51st igat torus
can he d ividenl iii to two categoi ies cu hsri nice fuel hic is nit l ‘.imrface mud hiods Surface
-------
inetho(Is have the adv antage of nol reqii iring It borehole and iii gruicral a large hioruiont .ii area
can be quickly covered Unfortunately, the interpretation of surface methods is often amnhigum-
Otis and add utmoim dl inform aLt )im is usim ally requ troth
Subsu rface methods requ ir a horehiohe and can only iiave’.t gate an area urn mediately
around the borehole ‘Pliey do hi’wevcr J)mo ide t-hcehleiit information omi vertical changes and
because of the wide variety of complementary tne.tsiircnientc whi it Ii can lie made’, they can
I)rovtde a great amount of information Obviously, the two approaches comple-nuent each
other nicely The subsurface methods provide the necessary detail but only in a small area,
and surface methods extend this det ul in the horizontal directions ‘flits is not to sa borehole
methods do not have pitfalls hut flint an integrated approach of surface and borehole geophy-
sics along with more conventional teJi uiiques N dcsirahle
OBJECTIVES
The purpose of lb is section N to out Ii i c a borehole loggiii g i mit C rpretation at r.ttegs for
hydrogeologists for use in the saturated zone Tl’c ‘levelopnicnt of a similar strategy for tIme
mu nsaturated zone may he part of a proposed hi Litre cooperatis e agreement The ohjectus N of
the strategy are
I Select a suite of logging touh3 that can be used to obtain the hsdrauilic parameters neces-
sary for contaminant transport studies
2 Develop a technique to qtiantitatuve combine the inlorniat ion from the selected logging
tools so t hat the liyd raulic parameters and their vertical variations can he ohtaiii i ’d for a
specific hazardous waste ite
Originall s t lie strategy was to he teMecl in i he hlehl, hut cl lie to factors be 3 nod (lie con-
trol of 1W I and EPA, lic logging eqiiipunen t to do the testing was not ,Lvail,il)le ‘Flit’ field
testing, and refinement of the strategy mat’ he arm importaiit part of a proposeil future
cooperative agreement hetween EPA and Dill
I!AZAIZPOLJS WASTE SITE INVESTJCATtONS
Before a strategy ca a hr developed, it i in pori a itt to ii iidu’ Ni and the en v iron nit ut in
alt cli it will he used Typically wells are sli allow and d ci ails of I ” rfor,ttions a iid in uud logs are
poor or unreluahte Unlike traditional logging wliit’li ic done in iineased hole’, jiu’,t after hole
cornplet ;on, logging at hazardous waste sites will normally have to lie done in PVC-cased
holes with ‘ .l ort perfora ted in ten ala Usually t lucre are several t ells iii a relat ivclv small area
;vli idi were iii itia ‘ly el ri lied cor mon utori ug lni t t Ii cli can he- used for borehole geopin sues
Typically the aite has an abundance of cult iiral actis ity which restricts the usc of some sur-
face geophysical methods
If bore hole mu ciii ods are to he of misc for Ii s’d rogeohegisu- ,, it m’. esserit a I hi :i t thi c i a unit cc
dluestiols of Ii ) d rologic sigmiuhicance lii particular ti is at rai egy at ris m’s to describe how the fol-
lowing parainet era vary wit Ii dept Ii effective auuul total porosit len or his ulraii lie conthiic—
tit it 3 ’, luttiology, grout nd—water t elocity, cacion e clia uigc Ca luacui of I lie forina i ion, and elect ri-
cal conductivity of the pore fluid
It is nccrssar to hiiuve a eli-ar ii nderstanil ag of how to g ‘t from t lie nieasmi re-inca i’, m ik cii
in (lie dcl to our desired goat’. The e luloi :ui Int l uurmmstrue-. have developed solihum—u ic iieil
23
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strategies t ) (10 this, but because they operate in different environments and have ilifferent
goals, many of their well-develohcd and tested strategies cannot be applied to ha7 rdoIis
aste site investigations While relying on the same priiiciplcs it is neees.sary to develop
modifications of equipment, field techniques and interpretation strategies The following sec-
tions explain a strategy which can be applied at a hazardous waste site
SITE ChARACTERIZATION
hazardous ,aste sites ar located in every concci .tb!e geologic setting Each one is
unique and r lationsliips developed for one site cannot he considered valid elsewhere It is
essential that relationships used in interpretations be based on data collected at the site under
study. To do this it is necessary to urihl characterization holes at each site
The characterization holes should be drilled with a technique than allows good core sam-
ples to be taken These cores will be analyzed for lithology, hydraulic conductivity, effcct ve
porosity, and cation exchange capacity This information will be coinl,ricd with the vchh logs
of the hole to provide the necessary site specific relationships for iterpretation of the other
wells from which cores are not available Although the characterization ehls do not provide
an absolute calibration of the logging tools, it permits the tool response to he related to the
local conditions.
Obviously, the characterization holes must he rcpresentatt% e of the site It may be neces-
sary to have several characterization holes and different relationships must be de clopcd in
different formations if the geologic cnvirorments were significantly different during their for-
mation Because most hazardous waste sites are sin all and the geologic processes that formed
them are usually consistent across them, the e trapohtion of rchstioa hiips across the site is
usually valid By comparing the relationshipc developed for a given unit with data from
different vells the validity of this assumption can be checked
INTERPRETATION STRATEGY
This strategy combines the gcophysical information from the ell logs and the geologic
information from the characterization vehh to answer the hydrologic questions of i uterest Fig-
ure 1 1 shows a block diagram of the strateg) and the reader is urged to refer to it frequently
The strategy is only developed for use in the saturated 7oae Additional strategies for use in
the unsaturated zone will be developed as part of a future cooperailve agreement
Porosity
The gamma density log v. hiicli measures the hulk density of the formation cnii he used to
determine porosity if matrix density is known The relationship is deri ed Irom the fact. that
the hulk density is a weighted average of the density of the formation’s constituents
Pa = fl, + (l-n)p, ,, (I I)
and is
= PI)Prn ( 12)
Pj — Pm
2’.
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REGIONAL
GRADIENT
DARCy’SLp [ OUNDWATER1
LAW VELOCITY
;t:: I(DARcYs LAW2I
EFFECTIVE 1
TOTAL VS EFFECTIVE [ If OROSITY
POROSI ’ ‘ RELATION
F F / I I I (
I HORIZONTAL1
_FLOW METER_fl
liii,,, I J• 7
Desired Information
— — — — Empirical Relation
From Literature
‘ ‘‘‘ ‘ FieldOata
I INDICATION OF
1 ANISOTROPY
III, / / /1/
IJ
4 INDuC7I0N
/7r’ii,i,F I
! ,,/I,Ii I
‘ :1 1ELEVIEWE t
Il/I/I /Il I
I
iIIfT IVITV MODEL L_, .1 PORE FLUID
(WAXMAN/SJA SJ_ J [ 9NDUCTIV J
! :oT OF’
I ACCEPTABLE
PERFORATED ZONE I
GROUNDWATER
VELOCITY
( FLOW METER )
Site Specific Data
— — - — Hydrologic Judgemant
F1( tR1 4.1. Interpret tioit Stratcgy.
-------
where
n = total porosity
p 5 = bulk density (from density log)
Pm = matrix density 2 6 gm/cm 3
P1 fluid density 1 0 gm/cm 3
The choice of a niatrrx density, xvIi ich is the deii ity of the forr;iatioii material excluding lie
pore space arid fluid, is determined by noting the mineralogy in the core samples Once the
mineralogy of a particular formation is known its matrix deuisitv can be calculated Ironi a
weighted average of the density of the matrix minerals
Effective porosity differs from total porosity in that it. is (lie percentage of total PO C
space available for fluid transport Fluid in pore spaces that. are dead ended (vuggs) or
extremely small (clays) is not mobile and hence this pore space is not included in effective
porosity In coarse sediments with inter-granular porosity, effective l.orosity will be the same
as total porosity, but as the percentage of (lead end poies increases or pore size decreases,
effective porosity vill become less than total porosity.
The core samples from the characterization ells can he evaluated to determine if there
is a significant. difference between effective and total porosity This can easily be clone with a
tracer test when the cores hydraulic conductivity is determined If there is a significant
difference, it is necessary to attempt. to develop a site and formation specific relation between
the two II this can he done then an effective porosity log can be ohtaiiieu by .lpl)iying (‘lie
relationship to the total porosity log
Hydraulic conductivity and regional ground-water velocity
There are two possible ways to obtain hydraulic conductivity and ground-water velocity
l3othi met liods Ii a c ad van t ag .s and d i -’ad vantages and witeii ui-ed together, t hey can vu hI
information on (he hydraulic anisotropy of the formation
Ilie most direct . way of obtaining hydraulic conductivity and eloeity is with a bore iole
thermal ground-water flow meter The use of this device for measuring Ii nid velocit and
hydraulic conduct vity, along with it.s l lm itatnoiis, is discus ed in detail in Section 5
An alternate met hod of (heterni liii rig hvd rail lie coiud iic ti ’ iiy is I,a ed on t lie more con vcii—
(tonal logging toots ‘l’lic first step is to (lcteriiiiiie (lie liydi •iiilie u,iidiict nyu y of iniany .luoi I
sections iii several of the hiorelioles This can l)c done by aii,ilysis of core sarTiphes or hydraulic
tests of short borehole intervals The intervals investigated must be representative of the
range of conductivitics in the formation To investig:ite I lie possibility of a relatmonslu p
bct een hiyclrauili conductivity and porosity the conductivity of ca ii interval is plotted
against the log derived p0 osiiy that . corresponds to t hat iuiterval Riclo (I G !) huts demon-
strated such relationships for shallow sedintiemits with intergi au iilar porosity It is mniport art I to
keep in mind the rektt ionshi ip, ii it e i,ts, will only be valid for tile formmiai ion and locality
from-n wit icli the data was obtained The rd at ionslu ill I ends to oCcur h,ccaitse wm thi in a given
(hepositioiial system any chanige iii sorting the conitmollinig f,u br for porosity, will also be
-------
accompanied by a change in grain size distribution, the ontrollirig factor for liy(lrauhic con-
ducuvity \‘arious sta’istical approaches can be used to qn ntify the rdationship an(I used to
pre(ltct the hydraulic cond iictivity that corresponds to a given porosity ‘Fli is relationslu up is
then applied to the porosity logs and a corresponding hydraulic conductivity log ca’t be
obtained
Once the hydraulw conductivity logs have been obtained, this information along with
the effective porosity log and the regional gradient can be used to Find the pore velocity from
Darcy’s Law.
it is important to understand the limitations a..J assumptions used in tiie’c two
methods for obtaintng ground-water velocity info ,iation The flow meter technique requires a
well with acceptable perforations A televiewer is commonly used to determine if this ccndi-
lion exists There are also restrictions on the minimum velocity that can be measured The
porosity relationship approach is dependent on the development of a porosity versus hiyd: uuiic
conductiv.ty reIatioris iip which may not he as unique as dc 5 red
Hydraulic anisotropy
In addition to direct measurement. of hydraulic conductivity, the thermal lb v meter can
be modified to directly measure the velocity direction The result i’, that the how meter can
be used in conjunction with the regional and local piezometric head gradient to obtain the
true hydraulic conductivity for an anisotropic aquifer For an anisotropic aquifer, the
hydraulic conducti ity is a second rank tensor, and the direction of flow is (in general)
different from the direction of the gradient
The direction of flow (e ) us a function of the gradient direction (8, ) and the principle
values of the hiydranlc conductivity tensor, K,, and Ic, , where r and y are the coordinate
axes of the principle d’rect ions Figure 4 2 shows the rel tionsiuips and (leflutitions of the vari
ables For more mIormation on anisotropy, see Bear (1079, chap I) Tue relationship bct’v en
0, and 0, is (leterrained by using trigonometrY arid Darcy’s La
ta I( 1 [ !_) (.1 3)
v. here
= K,, J, , K. ,, J , (Dircy’s I .a ) (I .ta,h)
and
I = J, ± 7 .1,
Subs utiitir.g eq (i) into (3) and using J, = Jcos0, and J, = Jsiri0, , e hv vc
= tan ( K, t .trO 1 ) , (i 5)
here K, Ic, 1K,,
‘Fhie un port a flee of (Jet ermiuul ng an ;sotr)pv cannot h> overeiiil)lu, ,lize(l ‘ts n e urn pie,
assume that the direction of the gradient is () (legrecs from t lie \-a\us .nid K, -=2, hen using
eq (I), the velocity direction would he nearh () degrees In other ord\ ch.u ngiig tie coil-
duct uvity ratio l) a factor of t’ o can change the elocity (lireci ion b ’ is niticli m 20 (begreN
27
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x
q -K,
ax
qy-K , E b
aY
Oqtari’(K,.tan e )
Where K =
K,,,
FICU E 4.2 The Reh rfonship fletween the Velocity and the Gradient
for an \nfsottop [ c ; quifer.
• •= ( 7
(isg.w. gradient)
q g.w. velocity
28
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Therefore, the degree of anlsotropv has sigiiiIicaii t mi plicatioiis for the placcineim t of ii-
gradient nionitorui wells and the prediction of contantinant plume lii gm a lion
Lithology
Borehole methods are of great help in detem mining lii .liology If a ilat is made wit ii
porosity on one axis and the corresponding natural g Lmitla response on tIme other a ms it may
be found tim at formations with similar litliology will form gi omips on tIme plot l’ig.m ic I .t is tim
example of this concept The core and geophysical data Iroin (lie cliam act riiai ion holes can he
used to make such a cro plot
This is done by plot tirig the hithology of nu mncromn, sa mmmt les Ii omit I lie di .ir.mel (flZ it iou
wells on the crossl)lot II enough samples representative ol time different lit Imologies are .iv.mil-
able, it will be possible to define the litliologmc bouiidaries on di. cros ’ plot Onice time crossplot
is defined, the mmnkiuo a lithologies in wells from wim icli core d Lta is unnva ii.ihlc can he deter—
mmne(l by ploRmug the natural gamma and porosity response on Lime crossplot and noting in
which lithology field it plots
Cation exchange capacity
The cation exchange capacity (CEO) of the format ion is import miit because it
slgnnflcantl ) affects the mobility of some co’mtnrninates and affects the geochemmstr and
electrical properties of the formation and pore w’a(cr CEO is primarily a function of cliv
content and type It is closely related to the natural gamma response because formations i tb
high CEC preferentmalh absorb high valence cations iticlmiding W 4 and Tb” Na(uralI occur-
ring ra(lioacti% c isotopes of these cations frequently account for tIme majority of the radial ion
associated wit clays In some enviroiin eiit,s tie Potassium mn the cl. ’y mat rix will In’ t lie
dominant source of ridiation (Donovan and Ilmlchie, 1970, Johnson and Lmnke, 1077 ) TIme
cores from tine calibrat,on well can be analyzed for CEC and a statislical correlation “aim lie
made to the n atmi ral gamm a log. From this relat ionslitp, t lie ( ‘EC corre .pond mug to a gi en
natu nil gani ma response can he (let C Nn i C(l This i elM iommsliip, if it, exists, cain t hen he
applied to all the holes aiid CEO logs can he oht a mne(l
Pore fluid electrical conductivity
Electrical conduct i ity of a fluid is closely related to time ionic streiigt Ii of the solmit ion
and in mans’, limit not all, instances can be an indicator of coimtmmnmnat ion Itnfoi t minatels , it is
not possible to d irectlv measure the elect rical cond iictmvity of t lie pore Iii: md ‘I’lw 11mm nI iii lie
well is a nai\t lire of fluids and Ii as been exposed to time mt mmio’.phiere an tI imence is not ins e —
sarmly represen at ive of the actual pore liii ol It is desit ,mhle to have a mint hod ol mimeasmi ring I me
mu situ pore .1 mmmd conduct ii ity
The induct ion log measures the electrical eoiidmicttvitv of t he foi moat ion, but. tlii is
influenced by many things Current iii the format ion is conducted liv t v o major l)athm\ .n ,
throu !i the pore fluid and by ion movenient along sum lace e’%chmaumgc sites In general time
m atri s does no’. coii tribute sigh ill cant ly to the electrical (onil to I iv ity
To (lL ’termnhm le tIme pore llmmid coinluictivity, it is imeccss:mm v i qimammt ilv I lmtse cff& cms TIme
path through the pore fluid is affected by poie llmiiil condmu t i mt’s mud polosli Tue smirlo
path is controlled bs’ the number of e clmaimgc sites that are avaIlable tom loll umoveiiiemim .mumtl
hence is related to ( EC
29
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0
S
w 0 SAND
POROSITY
• Data from a
particular depth
FT(URE 4.3 Llthology Cross Plot.
30
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In clay free formations, the nuitiber of exchange sites is negligible and the surface path
can hi ignored Under this situation, Archite’s Law (Keller and Friscliknecht, 1966), expre eil
here in conductivities can be used to express t he relationship between , , , and o’
= (16)
where
= bulk conductit ity (from induction tool)
a ’ 1 = fluid couductisity (iiiiknot;ii)
n = porosity (from density tool)
a = tortuosity {O 62—1 0)
m = saturation exponent c (2 0-2 is)
The values for a and in have been empirically obtained and are dependent on hthologv
The porosity can be obtained from the density log as e pIaine(l in Section 5 1, and the
induction log measures 0 . Archu”s Law can then be applied and an in situ pore Fluid conduc-
titity log ol)tained
If clays are present, the surface conductance along the surface of the c ia ) s cannot lie
neglected and it is nece ary to use a model such as that proposed by \Va\man and Snitis
(1969)
a’, =n m (B Q,+cr ) (171
w lie re
D =OOtG [ t—Ofiexp--(cj /0013) ;
— CEC(l—n)g Pa
loon
CEC = cation exchange capacity meq/iOQgni (from CEC log)
= 1 ) 1 1 1k formation density (from densit> log)
In this cqiiatic n a; is I lie on k nown, c is Mit ained from t lie induct ion log, and n is ob t tined
as in Section 5 1 Density is nieasii red wit I, the density log, and knotting i lie titliologt , ni C Iii
be obtained from t lie lii tnt ore (Keller ‘uid l”rischi h i cr lit, I O(iti) ( ‘KG is olit a iiieil Iroiti t lie
natural gamma log as esplained in Section 5 5 The Let iii I ? Q, is the addinonal rondii i lit tv
31
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from surface conductance Using Ui is equation to relate the log dtta, pore 11111(1 k t Ii iC ll Coil-
ducti% ity can be determined
it is important to enipliasize that tii is method allows (he ine,isu reineii ( of in iii silii
profile of pore I I U id conductivity that uses the CEC log to act oun t for ti e ii tine e cf c l.i vs
it is not necessary to determine the clay type or amount because only the (‘ [ C hic h Cs
ol)LainecI from the natural gamma log is necessary
COMPUTER IMPLEMENTATION
Large data sets and nonlinear relationships make computer processing a iieCeSsi( It is
desirable to record the data digitally, but ii ouR a limited nunhi)er of sites are iii esi gatcil
nd turnaround time is not critical, the analog (lata could be rccortkd and digitiaed Liter
The processing softwarc would only rcqii ire a microcomputer and a plotter The software
can be written to guide t lie interpreter t hiroiighi (lie str.it egy, and perform the import iii t . t t’sk
of keeping track of the propagation of tincei taiiitics It is not desircral)Ie to reduce (tic
software to a standardized package as this would encourage users not to take t l’e (true to
fully understand the assumptions in the processing seqiieiiee ‘ [ ‘his software package could he
readily used by small (1 rms ‘ [ ‘he actual field work con Id be contracted out, thus eltmiuuiiatiuug
the uic d of a high capital equipment cost
FUItTIIER REFINEMENTS
Effects of d’ illing diseurbances
All drilling techniques will d istu i b the form at ion in (lie immediate v cuui it V of the i ’ell
The effect this viil have on the interpretation is dependent on (lie degree and depth of dus tiir-
bance, and the effective penetration of the logging measurements if two gamma densut. logs
arc made ith two different son ree detector sp iciuugs, thet eby allowing me. uui cinent of lormi-
I ion density weigh Lcd over two di ifem en t horizon (il d ist a rice’S from liii bom chok, tii tid cat ion
of drilling disturbances can be obtained Uiider f,ivorahte condii ions, the d rilliiig cliecis can he
removed from (lie density measurement or at least nterv.uls of significant dmsumi,bances can he
identified and treated with an alternate approadi than is suggested here In heor time sune
concept could be used for the In(Iuction tool l)iit a suriall d iimiictcr multiple spacing intl uct ion
tool is not currently available
Tool response
Logging mnstrim men tat ion t Oes not make a nueasnrcTuieimt at S l’ .)mnt, liii t IL C.lii”C of 1)1 ii —
tical design restrictions, t tm ie ahiuc is a weighted aver uge over a short sect ion of t lie hort mob’
This spat ma! average varies depending on t lie tool design it. is irn portan t that when logs a i c
compared from different tools that the measuteinents are weighted averages of tIme sanie sec-
tion of the well This is part i iilarly ni portan t hear thu iii beds antI abrupt coim I set
The effects of d ffereiit spal id avcrmgmiig can he rt’iiioved by l igu ah liii em lug of tie ,i iii so
that the two ineasmi rernents arc averaged over the saimie tiut erv.ul. ar mu sou,ie ii.- .i umo L ’s l,
decon ohm lion, a digital process w loch removes t lie etlict’, of spit iii .tvcragi iig
32
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Improved electrical conductivity model
The calculated pore fluid electrical condi’ctlvlty is st rongly dependent on the way I lie
matrix properties are accounted for Because clay-bearing forin.ttions will li ve •L frequielo V
dependent electrical conductivity (Ward and 1’raser, I ‘)67) it is iniport ant to lone a iitodet
that is accurate at the measurement frequency 1 101( 1 tests of this strategy ‘ill he (lOnC wIth .(
Ceonic-s ENI-39 hich operates at a frequency of 50 I Il, tinfcurtuinately, condueti itv sInus
heLoming strongl ’ freqiieiiev (lepen(ieii I at aroiiiicl 51) H k .111(1 abOVe HIcrrI,)ru, the
Wa nan/Stints model is not wholly accept.i ble iii ticli •thov e this frequicuicy, it would lie uiscl iii
to develop a better model
There are major instrumental difficulties in meisu rung conduct Ivities of I easoii:ubk sued
lab samples at 50 l l1z The \Va man/Sunits irodel can be used but It is Iniportant to lit
are of its possible pitfalls in high clay conteii t formations . ddut boa I t bough t shuc.iuld l
given to developing a practical set of experiments from which au unproved 1110(1(1 (on lii he
developed
Effects of contaminants
This strateg assumes that. the site specific relat tonsluups obtained from the calibration
well hold throughout the site Although tliffcient relatuoiiships coukl he developed for tliffei cut
formations it is assumed that these relationships are valid throughout the foruuiatien far whin hi
they crc developed. In tin usual cases, it IS pos.stbic that the presence of (lie (Oh I :ui’u lii,u it
con Id alter these relationsli ips and in validate (lie iii tel pretat ion ltccauisc these relat ‘oui-h 11)5
are based on fat rlv sim plc ph% ieal and diem cal p ri uci pIes, a re i°w of t lie lit era lure a Ion g
with an uihiderstan(hing of the nieJiaiuisms tuivolved may make it possible to ulent if) couch—
Lions where the Contaminant might be altering the relationships usci! iii the un ei prtt a iou
CONCLUSIONS
A stratcgy has beca de eloped that, combines selected tradit’oiial borehole logging tti Ii-
niques with, hvdrogeologuc borehole equipment aiu(l metllodologv When t lie si ra egy h
aphded as out lined tnt thus section, the !).Iralneters I hint ire iuuiportaiit to Coiitirniuuuuit ihiuiiie
detection, monitoring and transport prediction can be cakuh,tted for e euy horellok’ 101 ,ited iii
and arotunid the hazardous waste site Because logging gis (‘a iuifnrnuauion %ithu respect (C (ItpIhI,
the strategy provides these parannelers as a fuiuc tion of dept hi in I lie aquifer ‘l’lie paranictei s
that can l)e obtained from this strategy inch do lithiohogy, total porosity, effect ive l)Oroslt y,
groui ncI— t ater velocit t-. h clra u huc cond uictivut y (inc Iii ding art isot ropv), c)ttioil c xcii a ii ge (-apaci I y
and pore fluid conduc:vity
ConsiderIng (lie wide range of conditions present. at Ilazardoils W,ISI sites it Is not possi-
ble to develop a universal tech ii iquie that will ork every where ‘l’hc iii! crpu i’Lat IOU sI rut egv
presented here relies hea 1k’ on tile USC of core data to det eruuiine site anul for matloil spec iii
relations bet eon measured parameter’, and para uuiet cis of lull cit st Alt l uoui hi t hi’ h t ions
used here have been noted in -ome geologic euuvlronn en Is t hi i s iiOt iiil ph> thu I lucy vuhI
a lwa S he I)reaent however when tile)’ are it. lesirera Ide to i a ke sd vu nt age oh m luenu, ‘a lien
the) are not an alternate appro-uchi iuiui he em ptovcd A lthuoiighi t lie stra I egy run be red iced
to a simple set of computer programs the h)roce si’g a ml lilt erhurCi it iOu ill list a lo a In (hOIi(
i.uy an undlvl(hli ,ul ‘a ho itaderstauids tile sugiuuficaiucc of hot Ii I he hu drohcgic , id gOhuh iysI( ii
assuiniiptioui’ , anil .elatior.s that aic ni ide ilOuig the huo(c ’ iiug p . 11 1 ailul (Iii ilti iihed it tIl l’)
13
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are appropriate
Macroscopic vari ’tions in hydraulic parameters are the most important co’ t ribiitioii to
contaminant mixing and dispersion in aquifers. This strategy is designed to provu’e sullicient
detailed information so that the mixing and dispersion process can he mo(lel d )y sirictly
advectivc transport processes. This is an attractive alternative to using advect ye-dispersion
models which require complex field experiments to (leterminc (lIsl erslon coefficients and still
often require trial and error calibration
Under a proposed cooperative agreement with EPA, DIII will evalu.tte this strategy at a
number of field sites Refinenients will be made to it based cii the fIeld experience
34
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SECTION 5
USE OF A BOREHOLE ThERMAL FLOW METER FOR DETERMINATION OF
GROUND-\VATER VELOCITY AND HYDRAULIC CONDUCTIVITY
INTRODUCT (ON
Subsurface data are required to determine hvdrogeologic conditions of hazardous waste
sites, to locate contaminant plumes, and to inoi:itor for Ic ks from disposal and storage facib-
ties Ground-water velocity is the most important inform.ition to help determine direction of
contaminant plume migration Ground-water velocity is a vector, possessing a speed (magni-
tude) and a direction It is needed to locate the up and down gradient monitoring wells and
to estimate potential contaminant pathways and tra el Limes
The traditional way of determining ground-water ‘velocity is to calculate it using Darcy’s
Law and regional or local piezometric head gradient information ‘Fhii is an indirect measure-
ment, and does not take into account velocity variations in the ertic l dimension A more
desirable method to obtain velocity information in principle would be to directly measure i in
a borehole One way of doing this is with a thermal groun’J-water flow meter
The ground-water flow meter e. aluated in this study is (lie N\’ As ociatcs Model 30L
Gco-Flo The instrument operates by inducing a heat l)ulse and monitor l’g the pulse nio e-
ment away from the source The fohlo ing sertion ‘ iiI descrihe in detail the theory of instru-
ment operation
It is necessary to understand the i’istrument before discussing the s ;eciflc objectives c f
this stuil , but the gene aI goals a e to determine the i ’ strument limitations and accuracy,
and eva aLe the manufacturer’s suggested calibration procedures In additiop, thieoiet iral
work viII be presented fo show that there is an alternative to the empirical calihration and
that it is possible in theory to use the inst rumoent to deternune (he hydraulic cond i.ctivitv of
the aquifer, in addition to the ground-water clout ’
It. would he niore approp’ ate to call the ir.s’ rument a ground.water ‘.eioi ’ meter, hut I lie terni
how meter us mu widespread use, so we use the ime tirmnummologv
‘15
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DESCRIPTION AND THEORY OF OI’ERAT (ON
The probe itself consists of a central heat source surroiiiidecl by five p.urs of t!ici rni-tors
The basic principle of operation is that the cer.tr.cl hie.tt source geiierates a pu Ise of he.it
energy This pulse ihilTuises radiafi) Iron the C enter nI (lie )rtuiw liv lie,tt, couiiliuc io u .u rid is
ad vected by the am l)ieiit grou id water ‘I’hu e d irectuoui .tuu d rel.et ire iii .igri i i iud c of tie ad \‘ectu C
groui nd—water velocity can be determined b) measti ring the temperal nrc (huiference bett cent
opposite pairs of thermistors (see Figure 5 1) \‘arioiis factors aifect the performance of the
instrii ment, Inclu(l in g thermal conductance of the sol ul and l.qiu id phi discs, sit nice ai ca of the
solid phase, thermal transfer coefficient of the liquid phase .iuid the advective rauuSport rite of
the fluid phase (lter ‘l’hie 1ui zv jnacki’r must lit into tie Il i’ iuug rv t gui ly iii oiuli’i to dii lucre ilie
conliiuuouus porous medium arrarigrmeiit of (lie .5 ciii cmii i .u n .uuuil (lie piienuucn.t U. picker
In practice, the probe is lowered dowii the hiorehiole to thu’ Io ’el at whi u hi the groumuid.
ater velocity is to be measured opposite a screened or shcttcd Sec lion The suclunerged probe
creates a short duration point source of heat After a period of I inic, the iel.itmvc thicrnual
diilerences between each of the li e pairs of t hiermistors arc d uspLiyd using a rot ary switch
which selects the pairs to be read The iiiforin.it ion is then used to alcui hate (lie groui uud—w it er
speed aiud (lirection
Prior to initiation of the heat pul5e, the thiermni. ’tc.ra do not iiecessariiy hiow ‘zero (eiin
perat.u re difference bet cen opposite pa irs of t huernnistcrs even iiii ihcr isothieruui.il cond ii ions
‘I’hims condition is referred to as the natural l)ackgroil mid i espouse ‘h’hie oper.itor rccor(ls the
temperatui re differences between the five pairs on thcriuubt o—s prior to uii(huiciiug the Inca t l)tilSC
to correct for this
‘rite probe is pron uled with onsistelu I orientat ion t o t .trds utoil Ii by uuie.uiu ’, of a set of
rods that sn a together in only oiie ci ir ction
3()
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NO FLOW CONDITION
FLOW CONDITION
DIRECTION
TMA X
THERMISTORS
HEAT SOURCE
FICIJRE 5.1 Opcrating Principle o the Borehole Thermal Flow 1cter
(from Ky—Associates)
-------
D PROBE
111 , — POUR N SAND
IhII 72 —
I)
F: . :: T : :
::: E 4D CI F
FICURE 5.2 Dingr of the 5—cr: End Cap a : d Probe.
38
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PNEUMATIC PACKER
AIR PUMP
“FUZZY PACKER
THERMAL
FLOW
METER
INTERIOR FINE MESH
BAG FILLED WITH
GLASS BEADS
4” WELL SCREEN
WIRE MESH SCREEN
FUZZY MATERiAL
- (SIMILAR TO THAT
ON A PAINT ROLLER)
F CURE 5.3
INFLATION
D’i igr im of the Packers for the 10—cm Borehole.
-------
The probe is on the downholc end, and a compass is attached to the iirjhole snap pole
Corrections for magnetic bearing are made with a l3rtuntou compass, and the standard prac-
tice is to orient the number I thermistor towards true north
l3ecai’se the probe measures the relative temperature difference between thermistor pairs
at a set time after the heat pulse is emitted, the measurement of ground-water spi’ed is a rela-
tive number which must be calibrated against some set of standards The manufacturer pro-
vides a small calibration chamber in the shape of a 15-cm t-tube The ca!ibrattoa process
involves filling the horizontal portion of the t-tube (see Figur. 5 -I) with porous material,
embedding the flow meter in the porous material, and induc’ng a series of known flow rates
through the t-tube The relati e measurements of the t-tube are plotted against the
corresponding known flow rates, thus providing a purely empirical calibration curve
POTENTIAL PROBLEMS
There are a number of significant problems associated with the calibrauon technique and
instrument usage If the porosity and permeability of the porous material are the sanie as that
of the Formation to be measured in the field, then the calibration is exact The manufacturer
offers no way of correcting the velocities for different aquifers, other than conductng t-tube
calibration experiments for each aquifer material Iii addition, the aquifer material placed in
the (-tube has been disturbed and probably has hydraulic characteristics different from the
in-situ values
Several potential problems and questions arose concerning die applicability of the tlicr-
mat low meter after initial field testing of the equipment (iless, a a! , l S-1) They inchided
the following.
o Effect of the two different packers on the ground-water velocity measurements
• Low flow velocity measurement limit
o Suitability of the t t.ube calibration chamber to construct calibration curves
In order to solve these problems and answer the questions, a number of specific goaTs and
objectives were developed
COALS MID OBJECTIVES
There are four primary goals of this study
I Evaluate calibration procedures for the flow meter
2. Determine limits of accuracy and precision under controlled laboratory conditions
3 Develop methods and techniques to c tend and improve accuracy of the flow meter
I Develop methods to yield hydraulic conductivity information from the flow meter
(a order to achieve these goals, five specific objectives were de eloped
1. Consiruct a sand box flow chamber for c liIiration experimenis to alow comparison with
the t-tLbe
2 Conduct e:perimnents with the (-tube calibration chamber amid the sand box to determine
t.tube calibr. tmon accurnc
-------
6” FLOW TUBE ALLED
WITH MD UM SAND
FIGURE 5.4 DIagram of the T—Tube CaiJbr Lion Chai ber
FLOW
PROBE
OUTFLOW
SLOTTED PVC SCIEEN
7NFLCW
METERED FLOW
(from YV—A soeiates .
-------
3 Test the 1 4-cm end cap and the 10-cm packers in th t-Lul)e 51 1( 1 the sand bo for accu
racy ai l(l 1) 1 ecision
4 Develop solutions for flow around and through a finder (packer) of differeri I hydraulic
conductivity than the surrounding aquifer
5 Derive equations to allow determination of hydraulic cori(ltieti it )’ i ing the flow meter
from the solutions developed in (.1)
DESIGN AN!) CONSTRUCTION 0!-’ TIlE SAND ItOX FLOW CIIAMIU:I1
The sand box w designed to allow precision (On t ro .tnd rvf)eat ability of die groti iud—
water velocity and to have uniform flow eliuracterist u’s t firoiughiout the ercucal cross-seclioui
Numerous 5- and 10-cm well casuiigs had to be installed, iliui’, the diriierisuons of tue sani! bo\
are rather large 1 2 m by I 2 m (cross-sect iouual area in I reetuout of i1o ) by 2 m (Ictigi h of
flow path ) The sand box is construct ed of 3/ inch pic\igl. s, and is held toget her ‘ s it h a uugle
iron and braced uthu 2 I and 2sb beams l’Igui re 5 5 is sit of eulguneeriuug d riwiuigs, pros id iuig
the coiist uction (letals of the sand box The cud chaiu’b-rs p ° id d couistant head reservoirs
which co’ild be adjusted in height. wth a preesion of 00! cm, providing ev -ellent rcprodiici-
bility of flow rates through the sand box l ugui e 5 ft is a d i.ugraiii of the cell casing .&rrai’ge—
ment within the sand box Each %ell casing was placed at !ea.st three easing (hiametcr 1
from its iearest. neighbor Some of the well casings were d hiherately placid near a .‘aU to
ahto study of edge/w .hl effects
Uniform size silica sind of #1 1 sie e size was used ii the sand box (geomet nc mean sui ,e
I 19 mm) Thus sand size was chosen prim aril to pre cit t san(l gr.tlns front cii tering lie cis—
ing slots When the —ar.I wris emplaced iii t lie bos, care v as I atc ’ri to avoid sI nil it ct ion
Using Darc\ ‘s Law, I lie hydraulic cond mci 1% itv of the sand t as cahemukited to be 2 ’2 ni/di
Determining the porosity is of primary uinport nce Tlim’ oliirnct ic floi iate (0), cross-
sectional area (A), effective porosil” (ii) and pore eloeni (v) are relited by the following sim-
ple equation
=
A ii
In this equation, Q and A ran be measured c it Ii great seen rac it is import in to hin e
a value for the effect e porosity that is equ.!hy arc;,rat so that i he celocit can he cab a-
lated ucruiratelr from the flow rate A nii mhcr of differe it met huc,l’, v crc tried to calcuLi e
por - - ‘ , ci ithi cilciulateil aluucs ranging front .tliproc iiui it Is — I l a I tm ur (Ii iii take iii
average, it was decided that the most. accmt rite aini appropi iii e mnetliritl V. 55 5 conduct •c
tracer test in which hi eaki hirouigh curves cscr(• ons( ruirt d Time etrictic t l5or it ci’as t lien
calculated based on tune-distance rebit monshiip- for pe.ik arris a! from one s cl i to another ‘l ’lic
value calculated from this proced mire c c as 13 7° Ta hb - 3 I is . su. iii mnar of I lie relevi n 1 p Ii -
sical and huvi rati mc parameters of t lie saud bos
SUMMAEY 01’ EXPE: w ii: ‘Vu’S
‘flie eaperuinent s arc dic idc l ill to fomi r c.itcgonies ciii RIm S ri smm uiiarm,wd iii Iii sect
‘Table 3 2 stm unmlri7es tIme esperuirients (ii it. ire d I ( tissed iii tim 5 (tori, :uinl I heir rehec au I
hlarame lers
42
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TOP VIEW
4’ ALUM AN LC ERACE
PLANK
FHO.4T VIEW
FIGURE 5.5 Construction Details of the Sand Box.
ETUD
DUDE VIEW
-------
I I
3 3/4”
FLOW
1’ 7 13fl6 ”
FIGURE 5.6 Placernenc of the Well. Ca’ gs in the Sand Box.
-------
T.ihk 5 1
PIi sie iI anti li draulie l t .tr tmcteN of hit’ S.ind Ilox
PAI AM [ ’I’lR
\‘ L ( T L
average gr lIiI SI7C
1 19 mm
hydraulk’ comitliictmvmty
in da)
effect i e porosity
13 i t
The initial evalu at ion e permmen is imiciti d d work with the Inst tii mcmi I ifl Open water, and
with the instrument inserted in sand wmthciut the end eap (naked probe in sand) Experi-
ments were also cond ucted to determine baSiC characteristics of the mist rimment incitid iic•
bias and other pztramet ers This ‘a ork helped gain fain Il iarit with the tmtstrmmmcn I, hut the
results were relslmvely insignificant and are not reported here
A 5-cm well casing was placed inside the t-tube Wit ! the flow iictem inside (lie ( asng
experiments were conducted for a range of elocmty nieasureinents ‘I his set of expemimnents
‘a as repeated in the sand hiox, hroi iding a direct cOmf>aris n of the cahthr it ton in tie t-t ui)C
and mu (lie sand box for the 5-cm casing and cmiii Cal)
The third set of experiments was conducted simiiiiar to the second sit, except t hit (lie
pneumatic packer was used ‘a itli 10-cm ‘ehl casings in both the t-timbe and the sand box
Similarly, the foti rth set tested (lie f 1 1z7V packer cahiii at ion in (lie t—tube and the sand
bo The luzi packer experiments were perfornied using the sante 10-cut will casiiigs iii Ii
were used for the pneuimiiatcc packer
EXPERlMENT. I REStJI.TS
The t3 pe of packer chosen to be used svit Ii the inst reriiciit h. d by fat I lie strongest effect
on instrument accuracy and operatiomial limit atiojis ‘Fhertfore, (hisciiSsiofl of experiimientil
results will he grotipe(l into three categories on t lie lia ia of the pa her t “sted The first
category will include all experinwuits with (lie S—i m cmiii cap ( e all ix liertcileiit s COfl(lil( tech
wit hi the 5—cm well casing) The seco’ul cat egory will uii Ititle au expet mcci is ‘a itli the pitcH—
matic packer and the t himrd categor ) will he .ill fuzzy packer experiments
Experiments using the 5-cm end cap in 5-cm vc1l casing
Thi is set of experiments follows the cal brat mon pro ed lire for t he 5-cit Lii d cap as recc,m—
mended hs the imtaniiiact tirer The diii front e’pt: iiliitii .!0I.\.t I— I ire plot vu iii I’ugtirt’
5 7 ‘lIme —a\is is the clocmtv ii ’ the t—ttilu ’ The \—.i\ s m the ector stilt of mite terlip(rai ire
ti iii ally lii e t’-ot rate is the iite u red pa riiti t Cr. and t’ic e lci. i a ku Ii ted by k ioi I ng I lie
utorosity
65
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‘I’.ible 2
Sn n Inary of I : %F tr IIiieIi Is
E perinent . Ilace C .t iiig I’,rcker \‘elocity
Number Sue ‘I’ i .
— J L J L! x)
201—Ad I
201—A3 2
201-A3 3
I
20 1- 113 I
201—133 2
201-113 3
201-113 ‘I
201-133 5
201-133 6
201-133 7
201-133 8
t—t’ib .
I-tu be
t-tuI e
t-tW
sand bOx
s .ii’I bo’
sand bo
sand bo
sand I)O
.tuid l)O\
sand box
Sand I)o
.5
5
5
5
5
S
S
S
5
5
5
S
end c. p
end
1-nd Cap
end cap
end LI
cud c.ip
end cap
end tap
end C I)
(Jt(I cap
end cap
end cap
5 ‘18
3 9
2 07
087
5 26
3 7 I
2 2.1
1 (12
0 55
0 35
0 105
0 OSO
•l0I—!\2 1
-I0I—A2 2
-l0I—A2 3
I0I—A2 I
101—132 I
101—Ill 2
101-112 3
101—132 -I
.101.132 5
- 10 1-UI 6
.101.132 7
101—1328
(—tube
(—tube
t—tuul,e
t—tuibe
saud bo
saud bo
s ’tiid box
sand bo
s..ud I)O\
saud Io
sand box
saud I)O\
10
II)
11)
10
It)
10
10
10
10
10
10
10
put -Il mat IC
put-u m.it uc
puieuhi .it it—
. lIlt1.itlC
piieiinu.utic
preuni.utIc
puteuniat it-
1 )ueIIlII . )tlc
ulIelunal uc
puieluuuint uc
pu eu m i t it’
I)liCIItI).ttl
5 66
3 83
I 0(1
089
I 39
2 22
I 01
055
035
(1 20
0 10
101-A3 I
101-Al 2
l0I— -\3 3
•I()I—A3 I
101—Ill I
101-I 13 2
.101-Ill 3
-1(11—113 I
101-113 5
101—lU 6
101-Ill 7
101—Ill 8
t-tu I
I-t ube
t—uuhe
t—tnbe
sand lw
5. 111(1 Iio
sand 1)0’.
sand bo
aand hci .
and bo
itud I)O\
- .jII(I I)0\
1(1
10
ID
II)
It)
10
10
0
tO
10
0
III
1u -,,
fuuiii
Iuu ,ev
1 1 11/ )
1u,.i
Iii ,,
f IIzt)
hiLly
fiuuv
fiuii
Iiu,.’v
I hII//’
5 1$
.3 99
2 II)
1(15
5 21
3 7 I
2 21
I 01
0 55
035
1)22
0 l()
1I6
-------
difference between the five opposing thermistor pairs The jilotted temperature difference was
calculated according to instructions provided by the n’anulac tnrer The arrows placed above
the data points are the indicated directions for each experiineii t North (or ‘iii)”) is arlmii ririly
chosen as the true directioi of Flow I knee, an arrow point iiig north represeiits a imieasiirei;iciit
with essentially no error in directional indication
The data show an excel!cn t linear relatioii Ii p lietwei’n I lie tern pera hut’ d ilTirt, iii
the true velocity of lie II ii i ii ‘ [ ‘he (low meter caLl read up to approxiiiiate k 500 reli I i c tern-
perat iire tin its, so the response covers aboii t !tt i of t he in st ru miment r a iige
Figure 5 8 shows die results fr m the series of experiments using the 5-c ni cmiii cap in the
sand box A good calibration is shown t or the dat a in the vekx tv range from ahioiu t 0 5
rn/day to the rn:iximu iii velocity tested (ahoii t S in/day) I lowever, the d i”ei tion ,d error gets
large for velocities lc I han I rn/day. The two diverging arrows near I lie 1)01 loin of I lie
graph in ic 4 tte the range of directions measured by repeating the experunien I ai I hat pnrtic ii —
Ur elocity
The velocity magnitude error gets large below 05 in/day This error at low velocities is
at tributed to the fact that the water moving very slowly thro ugh the end cap and the
diffusion of the heat pulse dominates the ad’wecttve traiisport Note that the average direc-
tional measurement is still towards north, indicating that repetitixe measurements iii the iehi
may provide a directLon of acceptable accuracy The resulting temperature difference is loo
small for the thermistor pairs to measure This will be discussed further iii the followiiig sec-
tions on the other two packers
The sand box calibration curve for the 5-cm end cap (Figure 5 8)is somewhat non-linear,
compared to the linear calibration in the t—tiibe (Figure 5 7) One reason suggested 10 I lie
non-linear calibration curve in the sar-d bat s as related to the nietliod used to uxtntroh Ilow
rate in the sand box The flow rate (and therefore x clocit ) was set b est .iblishiiig coiist ant
heads at different letels in the two end chamber re cr oirs iiuacciiracies in setting the con-
stant he ads cou t d have caused a non-hrmear relationship bet tecn head dihTcrences amid how
rates Thus hs potliesis was eliminated by plotting Figure 5 8 as flow rate (which is directl
measured) versus (low meter iitiits for the experiiiient series ‘flit s,inie iion-liuear ciir e was
observed
Another possible reason for t lie non—linearity is t l’at the saud-lan mmiv not 1 ic tpci 4 ituiig
wit Ii trii ly one—il nuensional low On the basis of sonic sun plc cl e tracer I esi s, I lie olmsu’rvech
[ how paths appear to be essentially hormzontah Therefore, i is not k nowii vhiv t lie iion-
linearity was ohscrved iii this set of experiiiients at this time lieaiise the same ItOiQiS
meditini was used for the t-tube and the sand box, a much helter agrcenieiit was expected for
the tea calibration curves
Experiments using the pneumatic packer
A l U—cm well was installed in the t—tnhie for time l)iieiiii latie packer aiud fuzz licker
e\perinients The data for the pne’mmatmc packer cxpc rmnieiits are shots ii i ’m l”ig’mre 9 ‘l’lme
results are much different than those for the 5—cm end tap l’hie tom al inst ruincnt rr poiise was
about S Flow meter un its, or only about 2’ of the inst ru mcii t raiige s se n iii Figmi u 5 1, a
very small change in thermistor temperature ditference md icates a large change in actual velo—
city The arrows show that the (hirectional acca racy is e en worse thin t lie migim it iide
-------
>-
>-
I-
0
0
-J
w
>
w
-j
()
10
8
6
4
2
00
FLOW METER UNITS
FIGURE 5.7 T—Tuhe Calibration of the 5—cm End Cap.
20 40 60 80 100
120
48
-------
10
8
S
4
2
0
>-
>-
I-
0
0
-J
w
>
LU
I-
-j
0
FIGURE 5.8 Sand Box Calibration of the 5-ca End Cap.
FLOW METER UNITS
0 20 40 60 80 100
120
49
-------
10
8
6
4
2
0
>-
0
0
-J
LU
>
LU
I-
cc
-j
0
F1(IIJflE 5.9 T—Tuhc Calibration of Lhe Pn uunhit!c PacL r.
FLOW METER UNITS
0 20 40 60 80 100
120
I ’)
-------
act ii racy, and is iisckss at veheit lea less I bait J iii/il.iy.
l ”igurt ’ 5 II) sho% ’ the lislogolis e\periiiieuits Iii I ht ,.iiiil l o (i c a.iiiic pir.iini teis .ts iii
the t—t iIie ‘l’he inst rnnicnt response is l ut U flow meter iii it ,, :i oltpose(I to only 5 iii t he
t—tIlI)e A larger response indi ate larger ieml erdt nrc ii drerCut ts and then tore lilore ad I we
transport aci oss the t lieriti i tors Siii e the t—tii lie a ad sand ko veloci I cs ate iii (lie s.i Inc
range (roughly 05 to 5 m,/d.i ) ), ii can he cont Itided hat the l,( ity iii t lie p .n her is Iiiglici
when It is iii the samiil I)oX tli.iii when it is iii the i—Liil ’e. Tue e pLiii.tI 11)11 for I his Is thu I lie
ratio of slotted area to total flow area i slnal’cr iii lie I— I nl,c ihi.iii iii (lie ‘, .incl ho ft can he
concluded (fiat the t—t ii be does not pros ’ ide an accept ,tl,le e.ilihira IOU prca cii nrc for (lie pit cii—
in a tic pack it beca use of the edge a iid it .dl etk I of I lie I — I uil)e
I’hc direetton.il accui av III the saiiil l for the Il Ijeilmit inc pa her is failly good fioiiu I
ni/il a ti roii ghi I he Ii igl.cst i’cloC itv inc isured (.i hoii I 6 in /41.1 ). I lo u ever, for tii t’\ pci i in c iii
vit Ii eloct ties a hove I m /d ay, there is an au erage hits (1 7 J 1 gru’cs (wit Ii a sI and .ii d div i .i—
tion of -i-,1— 3 degrees) Several of the esj eriiiici Is crc it 1 ;eaied seu’ci .iI I lilies ii ii hioiit. iitou —
ing the probe, and the inea .siir . d direction wss the s.iiuie to itlini (I 5 degree It is I lici chore
believed that this bias or offset i caused by the piieiimn ii ic pai kei rat her t haii e pci illic it t.uh
error
The fan—shaped sym hot near t lie I)catom of I ‘igure 5 IC) sIio i s I lie rauige of hut I i ati(l
thiici I ion for the elocit ics less I liaii I iii/d:iy ‘Flit’ l.irge Viii •tio,i iii u lu ii v Iui.ignhl udi’ ,iitil
direction is attnhuiited to the fact t hat n this veloi it v ranige, the IIiloiiiiI of waler Iiioviiig
Lb rough the packer is ucry small At ow web ici n s, tli e adu eeL ii e I railsjs irt Is doiii iliat ed liv
(lie di hitisi we heat transport As a result, t lie hica I p Iso Is spreiti ing lH i iuia rib’ b dill tision
and (lie pulse readies all thermistors at abnoat e acl Ii he saute tune \\ lien the ectot acldu—
Lion is pci formed, t lie icciors ate priuiiarih iioise .iiid i hc rcsulltu;ig itingit It Il(h( aiil ihtici tout
are essentially ineaiiinghcss
Experiments using the fuzzy packer
The calibration curves for t lie fiiiiu packer iii lie i—t hue and i hue s,ind hc ,\ ire sluouu a iii
l”ignrt ’s 5 II ,iiiil .5 12 rusliec iii ely \ViI Ii i!it’ Iiiziy pu her iii (hi (—I tube, (lie how itil. ti.u
duces a iiiargiiiilhy useful ( .ihuhur ,it .ni curie, alt hunuighi tl ’e dur tioits lit Conic uumtuclt il , 1 , hitlouv
,ihout . in/da ) lii l’iguire .5 12, lie dat:i show I hat I lie (bit tnt ’ter c.iniiol lie i ahil ,r.it ’uI wit Ii
lie fiiLI. pi her iii the sand ho , I here just lou ‘rn .iI inn estalilislit l t it ‘cii lie ll ,a
tiicter huh’, ,iiucl (lii’ achiiah ii tM ity
i tL lust it. ‘,( (‘Iii’ , iuhil ili.ut I lit’ ‘iii iiiti.iI ii f).i( ku ‘ luhii.iut s liii ti r iii (hi ‘,,tiiil I
iii tIn. i—tul,e, tehile tli reutrac us ltii f’.r lie lii,, pt her ‘I’m Ic.,si’ui 0 tli.iI ihii’ tii,zi
packer fits into (lie It) ( Iii utell (asiitg ters looscl , lc.iu ilig a () .5 (lii .iniiiiliis hi,’laceun tin’
packer .111(1 (lie iiu iilc of the easinig i .ill ‘1 be result. us I hi, t nu sier u ittcruiuk I lie c.usiuu , p hoti—
Ii.ihly llows tliioiigha the aiiiimuhis rallier than through tli pu k 1 r ‘Flue iu’,uil ith its of ulw t—t hic
cause a slightly better calibralion thin is possilile iii do’ s,iial h 4 ) ‘l’l’ .iiid hi .ililiio\i_
mates the (ounhubuona in an at tual ai 1 iiifcr iiiore C hosi ’lv i lt.uii the I—I uihie 50 t lie (tii(lIIsIO)i is
that :lie I ii /;, p:u her is not reconunuiemided b r use iii ii 1uu. h gro ’tiid—uu ,itrr it itst gal oils
Instrument accuracy and repcat.abilitv
(lsuuig the .5—cm end C II I and flow ir icr iii h ‘ t’id 10, si’ut nil t’siu’ruiiut its ileli’
repeated to gel uuiforinaliouu on the ,i ur,,cv ,iinl tp.ii.d.tlui oh (lie lloiu Iuie’tt u
SI
-------
10
>-
I-
C-)
0
-J
w
>
w
I-
in
-J
0
8
6
4
2
0
0 20 40 60 80 100
FLOW METER UNITS
120
FIGURE 5.l() SanJ Box CnI ibration of the Pncijinnllc PacL r.
-------
10
>-
>-
0
0
-J
w
>
0
w
I-
—I
0
8
6
4
2
0
0
20 40 60 80 100
FLOW METER UNITS
120
FTCIJRC S. 11 1—Tube Ca ibral ion of ti i iuLzy Pad.er.
-------
10
>-
>-
—6
0
0
w
>
w
I-
cr
:2
0
0
FLOW METER UNITS
FIGURE 5.12 Sand I ox CalLbratiOfl of ihe FULZy Packer.
0 20 40 60 80 100 120
‘ I;
-------
foiiu)tvIttg resiii are Valid fur r—riti vu i > i( h i ciiily, .11111 br Ii ku( liii grc..t r tliui (I
lul/da) et er ui rnea lurt (tier t , tture i,iLen ‘ ii( e’ stvcIt tt ii iiuui ri r vriig tIe pride or • Ii uti uig
1 10 W Oiid’t tOlls Ilie teiiui.ird liCVt.ltlurts Itere .ill less I ii.tri I’ 1 of I lie dVe ige’. U tile p1 he
tV.e, rc lnovr(I au(I reI)!sCe(i to its oritirtal ortirittit 1(11 •itl en Iii 110511 loll (to the iii t ol the
oI)ellfor’s tiiurlitv IC) (10 tlii’, uIliIill.iIiV), .111(1 111(1(1 I lii .iltte how (OlitiltiOli,, I iii ,I,utiuh.urul
(let Itt lorts were still lr s th.iit The ater.ugc ( ii tic lu_riupi rut Ire uiiiiu R ill S (ii VI 101 nV
InagIlitIlIles) Itere about tue one il,o ilottever , liii .tv(r.ig(S (if hue tudu it’d ‘ii it ‘ diii —
(Potts IICIC llS(I.uUt (Ilifererit l)’ li)’) (it 5 ilegrics IIW ( 1 1 1 k Ii lirt, turn ui intl ,ttiiii ul LU Ililhi( ut(
flitt ti is riot iiossilulc to 1(1111)1% 11111 C (iii Irt l I itlti(lit iii tire heir, huh tt it Ii let 1 It tutu u 1
degrees of (htree tton.rl accuracy lor red life pioi iciit , t iii , Lurid (ii all tire lulore thin iIi—
quite considering tire norm.tI itt’i Cr 1 1 1 1 1 1) ,rriil ‘upitnil tinu.uhihil v iii .eiiitler il iirutnht p ru -—
ic rs
‘I’I I I01t ElICAI t)E ’EJ.OI’M EN1
In L ro (I u c Lion
‘i’hc (_uitI)r.uttcull teCiiuit 1 iiL, iirovtiled lIt t it. iuiitiiil.u I uircr .iri jttreiv (iulJJlIuu ii, iul ii tug
iiuei.’uurctl velocity to Instrttninetit readout Iii (lie ion, ‘i lion we hive -,hu(jtt ii hi_u t it.
c.lhlhtatiotl itchiiiqtue siulfers frouti ilutm rt-)iu, itiohulutris it,uu (or he 5— lU (ill ,p iii ‘ — iii
well, (lie u_Liul)ratIon cuirv’s for tile stupid Ito\ lie (hilF(r(Itt tutu i l Ir the Itii hut, iii iuolil4hi u_ .e ii
Lire smite type of s.uud was ulse(i for both s (ts oh ,‘epcninuu nit’, i(rniigiiug (list unit d i(piiit I
multi iii in iuonui the field Still using it iii (lie t—Iuihu to uhitu iu > a Sl(e— ’ uhx 1111 1 .iiilir.utt,ti (I II I
ttoirhil lu vent qiRsI ioiuui,ic iia,,_d ou the toiiiiiit l ’ uOil t\pIt (Ill its ihotit iii I hit’, I itult
On tin luasus of (lie poor caiibn itiun i Oluipii I ’UIi ii tilt i h’ uiuior e\ptl iniuu_t’t,, it tecuiihul
lie Very (lesIrihilu to (lit (11) 1) 1 II 1)’ (C) 4111 (1 I h Ilitlill tu i ii itt liiic.utt iii, liii tii uurit liii
tVOt is Ill I iii , ‘ ,ict tori shun b(s (iii goal iii eldil on, it gee’s .u iii ujer ‘sti p 11111 Ii i I tiil i,uiihiIul ‘1
a tCChluiiltui( to ed in Ic formal tori lit ult.tiitt cOiiiIlit tt it’. [ rum hII• liii .isill(Iiiriii ’ , ‘iii ii I>’.
the hot’.’ hitter ‘I’hil, IcchiItu(lii( rei: .usinil—, . t,iiit ‘.1(1 lulll)(urturiI i i iii ( it un the hut’.
inlet en tii mt ii , (tOt Ire’. ioti,it’ iuetIi (Ott,iih ,_ itul
Direct calculation of aquifer fluid velocity
Iretri a. theoretical ‘utaiiihieiiitt the plIhliltun I lii lIt hil)iitli( Of i, the’.’. uriuriril itoh
through .t C) huinukr of ii’. (Iritlhnc ru),tuhile fit tt dun rent 1 1(1111 (ii uurioiiriliiug uquinfur hiir (lii ’ .’.
meter with tire ‘ —Ctui eituh ( III 1 i—i iii ‘.1(11 C’7i hit Iiu)uthlui if u, liii hi. rut ihuk ‘. hiiiilen It is
assumed that flow through the unul CS h i _i l Led with gi i lueS(L Ohet, i .uiu , Jut. .ini is
stea(iy— ,t,ite ‘iot tier asautrnpt on i I h ( the hi di iiihu i sIs —, ‘ u iii hue asulig shuts in’ Iii glignhuh l
hits us tI gt)()d •i,siIitihutnotn 111,14 r hut tin_il iiu,tt >iithil (c iii’ -, ‘. ‘ . Iiu ii ‘re tueriuiuhhv Iti ii hi I ,t ’ . iii
I riuusittout troriu l .rutuiuuur to I iunliiuhuiit hit,’.’.
‘Ilie se,ltittr,ri is OIut,uttt((l lure—ugh .i i ihic it un of ii ‘iii(Ilu \ )i t( lift i i t 11(111 hI ’uniiuuf.urt
3 11(httiOtis Sic applied a.t tln (I hiiiuhu_r ( u_uiLer) l)cliItuhhIry hit Intl itt u iiihi’ uuui’u ‘utile 1 hit
uuuni,h. lu- I Ii , sunric iii lhi& .uututtlt_r .uiutl tiut- i•ic Let is I cu c ulinnuhat I, i upr . h O 1114
ii(ut(ultiuii iutuu - ,1 ,ih,ct It thii_ sthui( is thtu. luciutiti.utt’ is l u ui it hu u ii l:ii tuuuui uuu I i ihi ii ’ . .u! ,bIi I
(hit 1 t hcnigt hit .uiiul Cull be fuilliltI \ . li(ut( I It uiiul \\lluii iii ug ( h ’lS ’ ) 1111 ‘(luit inu Is Ii
fu,t iii ( II I IV() ((.Ini h’ 1 ‘ h tti li_us ucill I ,r I lie OhiuIlu I ( uu u uuuh cliii lii Iii h_li 1_in I u ,,
(‘II
ii , (1 — — ‘ __. _ ‘__ I)
-------
and
w,=UK” i, (52)
where
it
I - K ,
A 1 =
1 Rr
K
r
- l÷K
K
K , =
z = x + t y (complex variable)
= ‘pecmflc cflscharge =
= aquifer pore se’ocmty,
aquifer pczro:ity,
= hy (‘ramilir cc4iUuCtmVit)’ or I lie aqimif ’ r,
K ,, = Ii > draulic ccttduttms ity rf time parker
56
-------
These complex potential equations can he separate(l into real and imaginary parts Tue
real part is related to the potential and the imaginary part is rcla ed to the stream function
Figure 5 13 shows the strea-ilirmes in the vicinity of the packed borehole for several values of
K,. For a packed borehole that is more permeable titan the aquifer, fluid preferentially moves
into the packer, causing greater velocity in the packer titan iii the aquifer \Viicn the p ci .ed
borehole is less permeable than the aquifer, fluid tends to move around the I)orehole causing
the packer velocity to be less than the fluid velocity in the borehole
To obtain the pore velocity in the packed borehole, the stream function eqirtlion is writ-
ten on the borehol ’ boundary Equations (5 1) and (5 2) are both valid on the borehole boun-
dary Equation (5 2) will be used because it is algebraically simpler The amount of low
through the borehole packer can be determined b finding the particular streamline which is
tangent to the borehole The value of the tangent streamline, 4’ represents the flow that
moves through half of time borehole (the half that is on the positive side of the x-a is), as seen
in Figure 5 11. Therefore, the total flow through the cylinder, Q 9 is twice t lie value of 4’,
On the cylinder boundary, the stream function can be written by obtaining the ima-
ginary part of equation (5 2)
4’ = K lrn(w ) = K” q !l (53)
The tangent streamline, , occurs at the point z =0, y =r 9 , and its value is (see Figure 5 13)
= K” q r (5 i)
The total flow through the borehole packer, Q , is.
Q 9 24’s = 2 r 9 K” q (5 5)
But Q 9 can also be expressed as velocity in the borehole times l)Oreliole diameter
= V 9 (2r .)n (56)
By equating the t %o expressions for Q (eqs 5 5 and S 6)
9
r’
Substituting in the expression for K”
V 9 ii 9 (I-s-K, )
= 2K, (5 7)
Equation 5 7 is an e tremncly important (Ici elopment If all of the varisblcs 0’ the right
hand side are knov n, one can directly calculate the average specilic discharge for the aquifer
In theory, equation 5 7 eliminates t lie need for empirical calibration of the f!ow meter with the
t- t U be Based on lie quest iona ble results of t lie calibration e\ pert mcmi ts, th is would b a very
desirable thing to be able to do
Equation 5.7 requires the instrunicn t to act uallv measure the borehole pl( ker elocit ‘ ‘
V 9 ) I 1owe er, the t hiermal flow meter reads oti t in ‘‘flow meter unit ,,“ ‘a hitch are act ii all ’
tern peratmire differences l)et %eeri thermistor pairs The flow meter miceds to lie niodified to
allow calnm lation of the p ick er velocit direct lv u c ii a mod iii ( ation woti 1(1 m equ ire th at the
57
-------
K . 1/10
— 3
K . 115
3
23
________________ 2
—2 —‘ 0 ‘l 2 30
Kr j1
- 3
3 1Q123
FIGURE 5.13 Streamlines Moving Around and Through a Borehole P ickcr
for Different Hydraulic Conduct vtty Ratios.
—2 —I U
Kr 10/1
53
-------
UNIFORM FLOW FIELD
kl=2 k2=1
FIGURE 5.14
Tangent Streamflnc for Determifl,1t on of ‘omifor
FIn d Ve I oc I ty dnd IIvd ran LC (u ntIR t iv i iv.
kl=1 k2=5
3 2 1 0 —1 —2 —3
3
2
1
0
3
2
I
0
3
2 1 0 —1 —2 —3
S’)
-------
output from each thermistor be recorded on a chart recor(I(r as a funci ton of time (st. rting
when the temperature pulse is initiated) Using the peak arrival times of the heat pulse for
each thermistor, the ad’.ective portion of the beat transport could be obtained ‘h’htis in turn
would allow direct calculation of the fluid veociiv in the packer
The other parameters on the right hand side of equation 5 7 are easier to obtain iii some
cases The packer porosity and hydraulic conductivity (n , and K, ) can he measured in the
!aborstory, and the aquifer hydraulic conductivmt can be obtained independently from aquifer
pumping tests, or other means
It should be noted that the aquifer hydraulic conduchvity (K,) measured liv a pump
test may be different from the K, mmmedmatcly adjacent. to the vertical poaltion w t iere meas-
urement with the flow r eter is being taken In such a case, the K, would be incorrect Thus
problem will be directly addressed in the following section
Equation 5 7 has been written in terms of q 1 ))uit if the :u 1 uiifer elocity \‘arics vertically
only as a function of porosity, (e g due to variations in hithiolgogic stratificationf then the
gamma density log will allow conversion of the specific discharge into aquifer thud vehocit ) in
situations where the relationship between effectu e and total porosity is known
Determination of hydraulic conductivity using the thermal flow meter
If the aquifer hydraulic conductivity is unknown, equation 5 7 c ’ n be used to (leterinine
it. The process consists of conducting two cxperimcnt with the flow meter, using two
different packers that ha e different, but known h’ drauhic conducti iues, K, 1 and K, 2 Thus
we have two equations, and two unknowns In the first experiment, we use a packer with
h draulic conductivity K, 1 , obtaining a packer velocity V, 1
1’ , n, 1 (l±K,. 1 /K )
— “pi .
In the second experiment, we change the packer so that we have K , and l’,
V ” , 2 n (l+K, 2 /K, ,
q. = — (.) I))
—
The porosities, n, i and n, , ma)’ be dilferent, but they can be determined in the laboratory
along with the h) drauhic conductivities, K, and K , 2
The two unknowns are q. and K 1 Thus by con(lucting two e\perirnerts, we can actu-
ally determine the aqii ufer hyd rau I ic cond ucti ity as well as t he specific disc-h - rgc This is a
ery significant hinding, because ii til this thiecuretucal clevekqirneiut, there has been no reason
to suspect that the thermal flow meter could bt used to obi am (lie aquifer hydraulic coiidiic-
ivity
oil
-------
Equations (5 8) and (59) can easily be solveil for the two unknowns K and q
= K— ) (5 10)
and
i . [ ’-i ) (511)
U
qp2 p2 p2
where q = — = *
q , , 1 p1 pl
arid Kpr =
‘ P I
This “two-IC,, method” theoretically offers an alternative to laboratory calibration with
the t-tube, hich has been shown to be of questionable value. This method would require a
fair!y in olved field procedure, and may be cumbersome for multiple measurements, hut con-
sidering the problems of direct calibration, it may he the only way to obtain an data fic i 1
the flow meter other than directional data
Potential problems and limitations
It should l)e strongly emplia ized that the method outlined in this seet,on, while theoreti-
cally correct, has not been tested in the laboratory or in the field. I’lans for future research
include using the sand box laboratory consLruct 1 for this pioJc’ to evaluate this niethiod for
obtaining aquifer fluid velocity and hydraulic conducti It using the thermal flow meter
Some of the problems that may be encoiint red include
1. The packer hydraulic conductm mty may be subject to considerable var lal)ility from one
measurement to the r’e t, due to rearrange:nent of the glass heads in the packer Sensi-
tivity of K 9 to such rearrangement is an important area of further research
2 The accuracy of the method may be sensitive to the choice of packer hydraulic conduc-
tivities, and/or scnsmti e to the aquifer hydraulic conductivity relative to the choice of
packer hydraulic conductivity
These and other probiems that could de e!op may limit the use of the method with the
thermal flow meter as it is currently designed lrndcrsi andiiig the prol)lems and limitations
mar lead to ideas for a better design of the thermal flow meter, taking into consideration the
design criteri.t that would make the method work in practice, as well as in theory
61
-------
SUMMARY AND CONCLUSIONS
Experimental work: velocity magnitude calibration
The results of the c:ilibration comparisons show that there are significant wall or
geometric effects when using the t-tube to provide an empirical calibration curve ior the
thermal flow meter when used with time 5-cm end cap in a 5-cm well ca_’ lng ‘rime calibra-
ion curve as hnear in the t—tnhe and non-linear in the sand box Thi us c :ilmbratioiis
clone in the t—t.iibe (to not apply to actual held situations The i-tube calibration i even
more questionable when considering the fact that the i—tube must be lilkd with (lh—
turbed aquifer material, which may have different !iydraulic properties than the original
aquifer.
The pneumatic packer had a reasonably good calibration in the sand box, but not
in the t-tuhe . gamn, the discrepancy appears to he due to the wall effects in the t-tuhe
The difference in the calibration curves between the t-tube and the sand box indicate
that the pneumatic packer should not be used for velocity magnit uide determinations iii
the field
The fuzzy packer has a linear calibration in the t-tube, but very small changes in
temperature difference are indicative of large changes in velocity This condition makes
the calibration curve too sensitive to provide good correlation between temperature
difference and velocity magnitude In the sand box, there is almost no corielation
between temperature and velocity, I bcating that most of the fluid is moving around
the fuzzy packer The fuzzy packer is the least useful of the three packer configurations
tested.
Experimental results: directional accuracy
The directional accuracy is good for velocities down to about 0 5 rn/day for the 5-
cm end cap. For repeated e permments in which the flow meter is not moved, accuracy is
at least ± 05 degrees If the flow meter is mo ed, the repeatability is about ± 3 degrees
The directional accuracy for the pneumatic packer was not quite a s good in the
sand box as (lie 5-cm end cap The pneumatic packer slio ed a consistent bias offset of 7
degrees to the east The results show dial the pneumatic packer can be used to deter-
mine direct’on for uel Dcmtites down to 0 5 rn/day, even though it is not capable of bring
calibrated for velocity magnitude Correction for the bias can be done by siih.i racting 7
degrees from the indicated direction
The fuzzy packer is inaccurate for the direct ion as v elI as the velocity uriagn it tide,
so it should not be use(l at all
In summary, the flow meter as presently marketed is only reliable for (hirectional
measurements using the 5—cm end cap and ithi additional caution, the pneumatic
packer
Theoretical work
Equations have been developed that express aquifer fluid velocity as a function of
(lie fluid elocity in the borehole packer, ii draumlic conductivity and porosity of the
borehole packer and the hydraulic condiictivit 3 of the aqu ukr \Vii li sonic modification
to the thierni ’I flow meter, it is theoretically pos ilde io measure thutse par:iiiieters
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Therefore, the aquifer fluid selocity can he directly Caletilate(l, thus eliminating the need
For the questionabe t-tube calibration procedure Although these equations are theoreti•
catty correct, they are untested Considerable experimental work vull be necessary to
determine how well they work with the thermal flow meter
The most significant result of the theoretical work is that the hydr-iulic conduc-
tivity of the aquifer can he calculated with the thermal llow meter This metlictd req uires
two measuremcr,ts to be tal en with the flow meter, with two different packers of
different hydraulic en diictivity. These two measurements provide two equations and
two unknowns, the açuufer hydraulic conductivity and the aquifer specific discharge If
the aquifer porosity is known From other borehole logs, then the arnifer fluid velocity
can be calculated as a Function of aquifer depth This ‘two-K, method” theoretically
provides the only known way of simultaneously obtaining aquifer hydraulic conductivity
and specific discharge vector data If it can be shown to he of practcal usc in the field,
it will be a valuable addition to the suite of tonls available to the liydrogeologist
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SECTION 6
SUMMARY AND CONCLUSIONS
INTRODUCTION
The corn plex nature of the grou n d— ater contain in at ion problem requires I lie collect ion
of extensive amounts of data iii order to understand the prol.lezn well eiioii h to recommend
and execute the appropriate reine(IIaI action It is nearl impossible to coileet adequate
amounts of data with tradi: ional liyclrog logic met hods, thus creating a need for tcchncdogv
that can help answer the complex questions that arise t% lien dealing with ground-water eon-
taminat ion
Geophysical methods have been widely used in oil ant mineral exploration SiBCC the
1920’s hlo e cr, due to their cost and the relative simphicit) of most previous grouin(i-waler
problems, geophysical methods have not commonly been used f-sr groti rid- ater in esi ig ii ions
As the eomple ity and consequences of ground-water eoiitainiu,atioii increase, geoI)hiysics is
becoming a more cost effect i e approach to aiis tr the I’) drc bgic qiiesi ions associated it Ii
ground-water contamination
Geophysical methicuds applic tble to hazardous \ aste site investigailons can be broken
itilo two ca cgories surface .uiid ‘ ,liI)slirface 111( 1 boils Siiri:u e iii i iods nIFtr Iti i’lvnuut:uge of
relal i ’cly lit tie cal)ital Investruen L at the site (iio borehole is aequiireii), an(l rapid Collect iofl of
data over a horizon tat arc a I however, I lie interpret at mu N cfi en a iii higuioims an ul ii iii it ed iii
:ertic.i I resolution Sn bsii rface methods require a boreliok• .uii.l can on lv iii es’ iga Ic aim area
iinm((l ately aron nd Lime borehio e I lowe er, t hey pros ide e\cLlleui t imiforlumntuGn on rt ical
changes in measured l)arame rs Also, a suite of coriupleiuiemitarv logs calu potentially pros mdc
ii nani biguous iii terpretation Df lydrogeologic parameters. espeeralk iii the ertical ii iiiiension
The t o approaches corn plemen t each otli&•r very well The sii bsuirlaee iuicthio(l, pros ide
the necessary vertical detail for a small area ami(l the stirlace met liods can then extend this
detail horizon tally between borehioles
This report Ii as (xsni iii ed only sim ku rI’ice geophi sic.i I mint hinds Uesc’a rclu in sti rface
methods is being perlornied by ot tier EPA coiitrimctors I’roldemns of site cli ,tracteri t ion con-
taminant plume (letect ion and nionitormiug ol contaniuuiauit liulnes iia e l,eer a(l(lresse(l us’ng
borehole geophysics
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BOREhOLE GEOPhYSICAl. METIIOI)S
Borehole methods fall into five major categories aoustical, electromagnetic, nuclear,
flow and dimension, a”d thermal. Major applications of these tecliiiiques iil( hide lii hologic
correlation, lithclogy, rock density, fractures, porosity, permneahi ity, flow, .iter level, water
quality, temperature gradient and hole (liarneter
hardware for borehole geophysical logging consists of similar basic coriipomcents for all
the different tools consisting of sensor, signal coeclitioners, and a recorder The sensor or
sonde receives power and transmits the signal to the surface through a conducting cable,
which also serves to position the tool in the hole by means of a winch Electronic controls at
the surface regulate logging speed and direction, power to the downhole electronics, signal
conditioning, and recorder responses i’hie return signal from (lie probe is a function of hitholo—
gic, fluid, and borehole parameters and is recorded and later .Iil.Ll) ied with a computer
LIMITATIONS OF BOREhOLE METHODS FOR IIYDROGEOI.OCIC T!AZABI)OUS \VASTE
I ’\’ESTIGA’F (ONS
Borehole logging methods have been developed pri narily by an(l for the petrolcu in
industry Logging tools arc designed to he used in open, birge diameter deep holes Several
logging tools are usually attached to one (lownhohe son(le that can be as much as 5 in in
length Interpretation schemes are designed to remove effects of drilling and to deterniiiie
psrameters that are of interest in petroleum reservoir engineering
The typical borehole that exists at (or aroun(l) iaiardoiis waste sites IS shallow (prob-
ably less than 100 rn) narrow diameter (5 cm) and cased, usually with P\’C, Teflon, or borne
other plastic None of th borehole tools designed for the petroleum industry are usable in
such an environment Many )wnhiole sondes used in the petroleum in(hiistry ha e 1 or 5
tools attached and are 5 m long Even if a soride such as this coukl lit in a typical 30-nc hole
at a hazardous waste site, Lice bottom 15% of the hok could not be logged clue to tl’e length
of the sonde None of the open hole logging tools (such as electric logging) can be used in the
PVC cased holes Since most downhole tools are desigri d for high teinperat iire, high pr ure
environments, they would be over-designed for (lie typical shallow monitoring well aiouiid
hazardous waste sites Moreover, the same tools may be subjected to hazardous chemical
borehole environments in monitoring wells aroiiiid hazar(loims waste sites for loch they arc
not designed to withstand
The interpretation schemes developed for the petroleum industry arc designed to remo e
effects of di mllmg Fluid from the (lata Logging is normally done belore or just .tfler hole corn-
1 det ion aiid holes are almost never re—logged, especially after casing luic’, been set f’or hca,ar-
dons waste si’e investigations, bordiole logging ‘a ill comnrmionly ho clone after P\’C casing his
been set, and ii. will be desirable to re-log holes on a regcil.ur basis to inon’tor for chuaiiges in
formation lluiid chemnistr) and groiiiid-water velocity
‘l’hie h)orehole logging p:ur:uineteN that .irc of iiilerest to (lie hiyihrogcologi- t in eat ig.uI ing
ground—wa t (‘r con tarn iii at iou are (flute d ihlereic t from the N’ ramiuct cr, comic micocu h -,ouighi t Icy tie
pci rolcuumic re ,ervour euigimicer As u result of (lie above ct,ic’,c,h,r.cl ions, it i oh hruimi .uu v iici )or—
L:uiice to (leVelOf) a iICW boreliol’ logging at rulegy I hit is dc— igmued to pros id e I lie iiiformmiai iou
aii ghu by lime Ii d rogeohogist for hi,u,ardomm S t-,t c site iii e l 1g. ’ t licils
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801W! (OLE LOGGING STRATEGY FOR HYDROGEOI.OGISTS
The vertical variation in hydraulic parameters w mtliiim iii a pi ifer is reeogiuitecl to be of
primary importa:ce in tleterrnin ing the late and t ransporl of comttamii*nn t in groimnd—wai er
systems ‘l’ra(litmonally, the process of hyd wily miani Ic dhlwr .iOn Ii is been though t to he the
dominant process causing contaminant niixiuig Macro-scale heterogeneity and vertical
stratification induce large variations in the advectuve Flow rate ol (lie ground water ‘l’his pro-
cess has been termed macroscopic dispersion and is (he dominant mechanism controlling coiu-
tammnant mixing and transport in many aquifers
Largely because or macroscopic dispersion, traditional groiind-t ater Flow equaluouts are
inadequate to describe contaminant transport iii aquifers Although it is important to account
for vertical variation iii l’ydrauhic parameters, (here has been htile effort to develop adequate
borehole methods that would provide such paranmiers
II borehole irietliocls are to be of use for hm drogeologist s, it is essei l ti ! that (hey a uiswe
questions of hydrologic significance In pa rticimlar, i ii e strategy on timed iii i ii us report
describes how the lohloss iug parameters vary w ithi ulcptli porosity, hydraulic conulmmct ivmty,
litluology, ground-water velocity, cation exchangc capacity of the formation and electrical
conductivity of the pore fluid
Ilazardous waste sites are located in every concei’. aide gcologic setting fl.iclu oiie is
unique and relationships developed for one site cannot lie considered -diul ekewliere It is
essential that relationships used in interpretations he based on data collected at die site under
s dy To do this, it is necessary to drill a characterization hole at each site ‘ [ he imitcrpm eta—
•i strategy combines geophysical information from the isell logs and geologic iiifoi inction
from tIme cliaracteriLation sell to ans er the lm’idrologic quieatioiis we are mmitcrested in
‘ I he assumption in this strategy is that the s’te specific relatiomiships obtainid froni the
calibration well hold t li roughiou t the site Shallow, ii miconsohm’lateo sedimnen is are among m lie
most heterogeneous deposus to be found It is n% es uected that (lie fornuatioius will be
laterally eontinous for the site specific relationships to hmoh l, only that the correlations
between lmthologmc c li aracterist ics and geoph sical riaramniters remain I lie sa inc Even this
assumption may he risky in sonic insvtnces and the prank ing huilrogeologist (lint un 1u10)S
this strategy must he aware of the possible variations tl.ai iiiay exist for specific problems
Although diFferent relationships could be developed for dmife ent formations, it is assumed that
these relationships are valid thi roughouit the format iou for which t hes %%ere developed lii
unusual cases, it is possible that the presence of the contaminant couill alter these relatioii-
s hips are luised on fairly simple physical and clmenin al priiiciluti’s a revme of the lit erature
along with an mii i i i ersta ii i ing of th iii ecbru ii si ns iii ’ ol veil in ay nih c it pos.— i ble Ic , mden i ify
conditions where the con tamum in a nt in iglit he alt eriuig i lie rilat ionsh ps misid in i lie iii terpi cia—
tion
us Or A HO ItE I IO LF , TIIE!tMAt. ( 1.0W MI:’rh:u FOR oi:i I:ttM(NA’r(ON OF GROUND-
WATER VELOCJTY AND ¶IYDRAtJLIC CONDUCT iV iTY
The traihit ion a! way of determin iiug grouinil—ss ai c c de c in h to c.ilcii l i e it ii i iig l).u rcy’s
Law, regional or local pie zoinct ne lien ul grad mu t in forimat ion, .miid effect i e porosity Ihims is a ii
indirect unea_suremeuit, anul docs iiot take unto accouimut i Fcit; anti l oris iii il ’ vertical
dunuensioum A uuiore ulesurahult met ho d to oht,timi elocmty imultriuiai ion ii ijtlt w ouild luu’ 10
66
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directly measure it in a borehole. One way of doing this is itli a thermal ground-water flow
meter, as described in Section 5
Laboratory attempts to calibrate the instrument for ve ociLy, including a specially
designed sandbox, were not entirely successful The data generated clearly iudicitcd that the
thermal flow meter, hen used with the fuzzy packer, is inaccurate for velocity as well as
direction. It is recommended that the fuzzy packer not. be used at all
Because of poor calibration comparis ns in the laboratory experiments, study was ini-
tiated to develop a way to directly measure velocity magnitude Equations were developed
that express aquifer fluid ve!ocity as a function of the fluid velocity in the borehole packer,
hydraulic conductivity and porosity of the bore! ole packer and the hydraulic conductivity of
the aquifer With some modification to the thermal flow meter, it is theoretically possible to
directly measure these parameters. Therefore, the aquifer fluid velocity can he directly calcu-
lated, thus eliminating the need for the questonahle calibration procedure Although these
equations are theoretically correct, they are untested Considerable experimental work will be
necessary to determine how well they work with the thermal flow meter.
The most significant result of the theoretical work is that. the hydraulic conductivity of
the aquifer can be calculated with the thermal flow meter. This method requires two measure-
ments to be taken with the flow meter, with two different packers of different hydraulic con-
ductivity These two measurements provide two equations and two unknowns, the aquifer
hydraulic conductivity and the aquifer specific discharge If the aquifer porosity is known
from other borehole logs, then the aquifer fluid velocity can be calculated as a function of
aquiler depth.
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