Re-Analysis of Hydraulic Tests

8/8/2019 Re-Analysis of Hydraulic Tests

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PNL-103UC-40

Re-Analysis of Hydraulic TestsConducted for Well 4A

F. A. Spane

January 1995

Prepared forWestinghouse Hanford Companyand the U.S. Department of Energyunder Contract DE-AC06-76RLO 1830

Pacific Northwest LaboratoryRichland, Washington 99352


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This repor t was prepared as a n a c c o u n t of work sponso redby an agency of the Uni ted States Governm en t . Nei the rt h e United States Governm en t no r any ag enc y thereof, nora n y of t he i r em p l oyees , m ake any war ran t y , exp res s o rimplied, or as su m es a n y legal liability or responsibil i ty fort h e accu racy , com pl e t enes s , o r u se fu l nes s of a n yinformat ion , appara tus , p roduct , or proce s s d i s c l o sed , orr ep resen t s t ha t its use would not infringe privately ownedrights. Refe rence herein to any speci f i c commercia l.produc t, p roces s , o r s e rv ice by t r ade na m e , t r adem ark ,manufacturer , o r o therw ise doe s no t necessar i ly cons t i tu teor imply its endo rsem ent , recommendat ion , o r favor ing byt h e United States G o v e rn m e n t o r a n y a g e n c y thereof. Theviews and op in ions of au thors expressed here in do no tnecessari ly state or reflect those of the Uni ted StatesGovernm en t or a n y a g e n c y thereof.


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DISCLAIMERPortions of this document may be illegiblein electronic image products. Images areproduced from the best available originaldocument.


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Pacific Sorthwest Laboratorie2aitelle 3 0 ~ I c r a : d?.o.ox 909Xickland. :\ashing;on 99252T e i e p h o n e 1509) 3 7 6 - 8 3 2 9

March 17, 1994

Mr. Craig SwansonWestinghouse Hanford Company740 StevensRichland, Washington 99352MSIN H6-06SUBJECT:Wells 4A - 4TFinal Draft: Re-Analysis of Pumping and Slug Interference Tests atDear Craig: .The following represents the final draft of a letter report that provides are-analysis of the constant-rate pumping test and slug interference t estconducted at wells 4A - 4T. The. re-analysis includes the effe cts o f wellborestorage, partial penetration, and vertical anisotropy.demonstrates that comparable results were obtained from both the pumping andslug interference characterization tests.

The re-analysis

Sincerely,

2~ Li,q.eFrank A . Spa ne, Jr., Ph.D.Staff ScientistHydro1 ogic and Geochemica l CharacterizationEarth and Environmental Sciences CtnterFAS/Attachments .cc: R W BrycePD ThorneDL Stewart

V R VermeulDR Newcomer


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Mr. Craig SwansonMarch 17, 1994Page 3

2.0 PUMPING TEST RE-ANALYSISThe re-ana lysis procedure for the pumping test drawdown phase obse rved at well4 A included t he following analysis elements:

an initial diagnostic drawdown derivative analysis,a late-time, Neuman Type B curve analysis, anda compl ete unconfined aquifer type-cur ve analysi s,including wellbore storage effects.

2.1 Diaqno stic AnalvsisCombined drawdown and drawdown derivative plots have been shown to be apowerful diagnostic tool in identifying operative flo w conditions and fac tor sinfl uencing drawdown during constant discharge pumping tests (e.g., Bourdet etal. 1983, 1989, Spane 1993).drawdown d erivative plot f or observation well 4A . The drawdown derivativeswere calculated using the DERIV program described in Spane and Wur stn er(1993).th e following operativ e flow conditions during the test wer e interpreted:

Figure 1 shows the combined drawdown a ndBased 0n .a diagnostic analysis of the pattern exhibited in Figure 1,

combined we1 1 bore- torage and del ayed-yield responseconditions during the early phases of the test ( i .e.,up to =: 4 min)unconfined aquifer, Type B curve response characteristicsbetween 4 and 500 minvari able drawdown/derivative pattern after 500 min,most likely attributable to discharge fluctuations.

2.2 Type B Curve AnalysisTo provide an initial estimate of transmissivity and specific yield, drawdow ndat a during th e test period indicative of Neuman unconfined aqu'ifer, Typ e Scurve behavior was analyzed (i.e., for test times 2 4 min).Type B drawdown and drawdown derivative plot matching procedure descr ibed i nSpane (1993) was used in the test analysis.generated using the WTAQl program described by Moench (1993).Moench (1993), the WTAQl program runs faster and does not exhibit so me o f thetest instabilities that are sometimes exhibited with the D E L A Y 2 program

The combinedDrawdown type' curves w er eA s discussed in


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Mr. Cr i g SwanMarch 17, 1994. Page 5.where rc = r a d i u s o f the wel l s c r e e n

= r a d i a l d i s t a n c e f r o m c e n t e r o f well t o* the ou t s i d e s a nd / g ra ve l pac k

n = p o r o s i t y o f th e sand/gravel packFor well 4A, given a well . screen r a d i us o f 0 . 051 m (0 .1 66 7 f t ) , a r a d i a lg r a v e l p a c k , d i s t a n c e o f 0.102 m (0.333 f t ) , and an assume p o r o s i t y o f 30p e r c e n t , y i e l d s a rew or well 4A of 0.070 m ( 0 . 2 3 0 f t ) .A c a l c u l a t i o n of the r for the pumped well (wel l 4T), however, i s mored i f f i c u l t b ecau se of the " n a t u r a l " s a nd/ g ra ve l pa ck t h a t was deve l oped a roundthe well , d u r i n g previous well bo re developm ental pumping. As no t e d - i n S wa nson(1992) several b a r r e l s of s a nd and s i l t were removed from well 4T d u r i n g thedevelopmental pumping phase. The presence o f a n e x t e n s i v e z o n e o f " e n h a n c e d "pe rme a b i l i t y s u r round i ng t he i mme d i a t e w e l l bo re i s i n d ic a t ed a l s o b y the b i -l i n e a r r e s po n s e e x h i b i t e d a t well 4T dur i ng th e s l u g t e s t (see F i g u r e 3 ) . Asa means o f e s t i m a t in g p o s s i b l e v a lu e s for th e ren f o r well 4T, t h e r a d i a ld i s t a n c e , rw, o the o u t s i d e b ou nd ar y o f the deve loped "na turJa1" sand/grave lp ac k c a l c u l a t e d ba se d on t h e known d i s p l a c e me n t , V = 0.027 m (0.96 f t ) andi n i t i a l stress r e s pons e , H, = 0.168 m (0.55 f t ) o b s er v e d a t well 4T d u r i n g theA pr i l 14, 1992 s l ug t es t (see Figure 3 ) .re1a t i o n s h i p s were deve loped:

For this c a l c u l a t i o n , the f o l l o w i n g

where V, = s l u g t e s t volume disp lace me nt; (0.027 m3)= disp lacement volume w i t h i n well screen= displacement volume w i t h i n n a t u r a l s a n d /

VWC

vw.3 grave l pack zone

where . "wcwhere

Re-ar ranging Equa t ion-"wa

A l s o n o t e t h a t from a

2= R rct H, = 0.0067 m ; (0.237 f t 3 )0.113 m (0.370 f t )r- = r a d i u s o f well 4T well sc reen; .-.2,

't - vw , = 0.020 m 3 ; (0.723 ft')modi f i c a t i on o f a r e l a t i o n s h i p i n Bouwer (1989)


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obtained with the Type B cur ve analysis and to those previously reported hySwanson (1992).storativity is considered to be very qualitative; primarily d ue t o the lack ofearly- time dat a (i.e., the first 25 s), and the lack of sensiti vity fo r smalldrawdown measurements (Note the "stair-stepped" pattern for drawdowns lessthan 0.015 m).

It should be noted, however, that the estimate for

3.0 SLUG INTERFERENCE TEST RE-ANALYSIS

As noted in Section 1.0, th e original slug interference test analysis wasbased on th e analysis procedure presented in Novakowski (1990), which isdependent on fully penetrating wells within isotropic confined aquiferconditions. Subsequent to this analysis, analytical methods have beendeveloped, which provide the opportunity of extending slug interferenceanalysi s to a variety of tes t conditions including: unconfined aqui fers;partially penetrating wells; anisotropic conditions; and well bore sto rag eeffects. The basis o f the analysis extension is based on analyticaldiscuss ions presented in Novakowski (1989), Peres (1989) and Peres et al.(1989), which demonstrate that slug tests can be represented as a specializedform o f constant-rate pumping tests. As noted i n Peres (1989), the slug test.wellbore solution can be "... btained directly from the time derivative ofthe constant rate wellbore storage solution ... (and that this relationship)is also valid fo r any reservoir/well system and holds at any position with inth e reservoir. "A detailed description of th e procedures for slug test conversion are notpresented i n this lett er report. The reader should consult th e aforementionedrefere nces fo r analytical justifi cation of th e slug test convers ion method.Briefly stated however, slug test data were converted to equivalent head(pumping test) drawdown data by integrating th e observed slug test head dataover the observed test time, as indicated in Peres et al. (1989).Multiplication o f the observed slug test head dat a by the observed te st time,yields the logarithmic derivative of the equivalent head chang e for aconsta nt-rate pumping test.Figure 6shows a comparison of the drawdown and drawdown derivative responseobserved at well 4A during the constant-rate pumping test, with the convertedequivalent head and head derivative response obtained during t he sluginterference test. A s indicated in the Figure, similar pattsrn shapes areexhibited. I n order to equate the two test responses, however, the s t r e s slevels for the two tests need t o be normalized.As noted in Novakowski (1989) and Peres, et al. (1989), the instantaneousdischarge rate, Qi, (gpm) imposed by a slug test can be calculated3diroctly byth: disp la ceme nt volume, V,. For a displacement volume o f 0.027 m (0.96ft ) , a Q, value of 27.2 L/min (7.18 gpm) is indicat2d. To normalize t h e slug


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of predictive response shapes are still possible.responses can be greatly reduced, however, if expected (common) bounds canapplied f or some of the formation hydraulic properties.interference type curves generated for the antlysis of the well 4A testresponse Jntjluded:10 to 10 m /d (lo2id l o 5 ft2/d).various hydraulic property combinations, individual type curves were generatedby systematically varying selected parameter estimates. Figures 8 through 12show the results o f the sensitivity analysis. A s expected, variation in theselected hydraulic property values causes significant changes in the shape andamp1 i ude o f the predicted slug interference response. The foll owing generalobservations are provided that summarize the sensitivity o f the predicted sluginterference response t o hydraulic property variation (i .e., given well 4Atest site conditions) :

The number of predictiveLimits used for slug

S = 0.005 to 0.4; S = 10- to 10' ; K, = 0.01 to 1.0; T =. To examine the sensitivity of the predicted slug interference response to

transmissivity is the principal parameter control1 ing thetransmission (i .e., arrival time) of the interference response(Figure 8)storativity exerts a significant influence on th e amplitudeand shape o f the initial slug interference "hump" (Figures 9and 10)wellbore storage effects dampen and delay transmission of theinitial slug interference response observed (Figure 10)the storativity/specific yield ratio affects primarily theslope of the recessional limb o f the initial slug interference"hump" response (Figure I I ) , andvertical anisotropy, 1 ke storativity, exerts a significantinfluence'on the amplitude and shape of the initial sluginterference response (Figure 12) ; however, the predominant regionof influence is the peak amplitude and recessional limb of theinterference response.

4.0 SUMMARYA general procedure is outlined for generation o f slug interference testresponses within anisotropic, unconfined aquifers with partially penetratingwe1 1 configurations. The procedure i s based on conversion of avai ab1 eunconfined aquifer constant-rate pumping test type curves, which have beenmodified to account for the affects o f pumping well wellbore storage. Resultsof sensitivity analyses, indicated that variations in T, S, S v , K, exertsignificant influence (in varying degrees) on the transmissioh, amplitude, andshape of the slug interference responss.


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5.0 REFERENCESBourdet, D., T.M. .Whittle, A.A. Douglas, and Y.M. Pirard.' 1983 . "A NewSet of Typ e Curves Simpl ifies Well Test Analysis. World Oil, May: 95-106.Bourdet, D., J.A. Ayoub, and Y.M. Pirard. 1989. "Use of Pressure Derivativein Well -Test Interpretation. SP E Formation Evaluation, Ju ne 1989: 293-302.Cooper, H.H., Jr., J.D. Bredehoeft, -an d I.S. Papadopulos. 1967. "Response ofa Finite-Diameter Well to an Instantaneous Charge of Water." Wa te r Resour cesResearch. 3 (1 ) : 263-269.Dawson, K.J. and J.D. Istok. 1991. Aquifer Testinq: Desiqn and Anal vsis ofPumpins and Sluq Tests. Lewis Publishers, Inc., Chelsea, Michigan.

'

Earlougher, R.C., Jr. 1977. Advances in Well Test Analysis. Henry L.Doherty Series, Monograph Volume 5, SOC. of Pet. Engineers, AIME.Fenske, P.R. 1977. "Radial Flow With Discharging-Well and Observation-WellStorage." Journal of Hvdroloay, 32: 87-96.Horn, R.N. 1990. Modern Well Test Analysis: A Comou ter-A ided Armroach.Petroway, Inc., Palo Alto, California; distr ibute d by SOC. Pet. Engrs.,Ri ch f el d, Texas.HydraLogic. 1989. ISOAOX: Operations Guide. Hydra logic, P.O. Box 4722,Mi ssoul a, Montana.Moench, A.F. 1993. "Computation of Type Curves for Flow to PartiallyPenet ratin g Wells in Water -Tabl e Aquifers." Ground Water. 31(6) : 966-971.Neuman, S.P. 1975. "Analysis of Pumping Test Data from Aniso trop ic Uncon-fined Aquife rs Considering Delayed Gravity Response." Water Resour. Res.l l ( 2 ) : 3 2 9 - 3 4 2 .Novakowski, K.S. 1989. "Analysis of Pulse Interference Tests." Wa te rResour. Res., 25(11) : 2377-2387.Novakowski, K.S. 1990. "Analysis of Aquifer Tests Conducted in FracturedRock:Program for Generating Ty pe Curves." Ground Water 28(1) : 99-105 .A Review of the Physical Background and the Design of a Comput erPeres, A.M. 1989. Analy sis o f Slug and Drillstem Tests. unpub lished Ph.D.dissertation, University o f Tulsa, Tulsa, Oklahoma.Peres, A.M., M. Onur, and A.C. Reynolds. 1989. " A New Analysis Procedure ForDetermining Aquifer Properties From Slug Test Data."Research. 25(7) : 1591-1602. Water Resources


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8 : 1 I 1 1 20 : Well 4 A

x D r a w d o w n D a t aD a t a D e r i v a t i v e0

0 - L - s p o c i n g = 0 . 29 : - IQ ) .5 /-.0 05 0.-;E ? -000 0 ' :c -E -Ou -3 00 0 -L.- .

0 -J -c -0 -c -0 -- 0 :

0 0 -0 -

a?:

3 0

r?:L . .-

0 .00 .

FIGURE1. D ia gn os tic Drawdown and Drawdown D er iv at iv e P lo t Fo r Well 4 A .

/JX,A"n I ;x d r o axA 0rn& A 4. A kxxxx discharge

&

1 -t

4f luc tua t ions ?T y p B Curve

lSA ' respcnse tei-taviorwellbore storage . 3effects r o = 9 . 1 7 m

r e w = 0 . 4 2 7 m0 = 9 2 . 7 L / m i n

1 1 1 10. 1 . o 1 0 . 9 100.0 1000.0 1000 .0


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projected yo = 0.156 ft (0.0475 a)

Q O O O O 0 0 6

0 0

1 0 - 2 , . . . . . . . * . , . . . . . . , . . , . . . . . , . . .2 31 Time in minutes

FIGURE 3 . S l u g T e s t Response A t Well 4T; T es t Date :(adap ted f r o m Swanson 1992) A p r i l 14, 1 9 9 2 .


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Mr. C r a i g SwansonMarch 17 , 1994Page 17

st.0 .-

T = 2 5 4 r n Z / ds = 0 . 0 0 1S y = 0'.025K D = 0 .10

1 1 I 1 4in c o n f i n e d A q u i f e r W e l l S AW e l l b o r e S t o r a g e D r a w d o w n D a t a-

FIGURE 5. Combined Drawdown and Drawdown Derivative, Com plete UnconfinedAquifer Type-Curv e Analysis For Well 4A. .


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Mr. Crai g Swan sonMarch 17, 1994Page 19

009

000c 1 I 1 1U n c o n f i n e d A q u i f e r

W t l l b o r e S t o r a g eT y p e C u r v eT = 2 4 2 m 2 / dS = 0 . 0 0 0 5 '

s / s y = 0.018K O = 0 . 1 4

x Well 4 A T e s t D a t ar o = 9 . 1 7 m

rew = 0 . 4 2 7 mr w m = 0 . 0 7 0 m

H o = 0 . 0 4 8 m

0.0 1

FIGURE 7.

0.10 1 . o oT i m e , m i n

10.00

Unconfined Aquifer Type-Curve Analysis For S1 ug Interferenc e TestRespons e Fo r Well 4A.

1 0 0 .


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Mr. C ra i g SwansonMarch 17, 1994Page 21

000- -0 .

0E O -.? :a J 0 .* -c0 -0 .QalE -0)L -

fna* 0al -L 0&ST0 .

0

90

T = 2 4 2 m 2 / ds / s y = 0 . 0 1 8K D = 0 . 0 1 4

I 1 IS e n s i t i v i t y A n a l y s .s = 0 . 0 0 0 1s = 0 . 0 0 1Well 4 A T e s t D o t o

r o = 9 . 1 7 mr e w = 0 . 4 2 7 m

r w r n = 0 . 0 7 0 rnH o = 0 . 0 4 8 m

--.----.-

-

..*..-*e..--

i:

F i n a l S o l u t i o n-1 . . , , , , , I

FIGURE 9. S e ns i t i v i . t y o f P r e d i c t e d S l ug In t e r f e r e nc e R e s pons e F o r W e l l 4 A ToV a r y i n g S t o r a t i v i t y ( T = 24 2 m2/d, S/S = 0.018, K, = 0 . 1 4 ) .Note: Me1 1bore S t o r a ge E f f e c t s a re i nc? uded


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0.L

' S e n s i t i v i t y A n a l y s .- S / S y = 0 . 0 0 5- - - - - - - - S / S y = 0.05

T- = 2 4 2 m 2 / dS' = 0.0005K O = 0.1'4

X W e l l 4 A T e s t D a t ar o = 9 . 1 7 m

r e w = 0 . 4 2 7 mr w m = 0 . 0 7 0 m

H o = 0.048 m

F i n a l S o l u t i o n1.00 . 1 0 . 9 0 I O 0 . U O.0 0 . 1 0 T i m e , m i n

FIGURE 11. Sensitivity o f Predicte! Slug Interference Resp onse F o r Well 4 A ToVarying S/S, (T = 242 m / d , S = 0.0005, K, = 0.14).


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TABLE1. Comparison o f Hydraulic Test Analysis Results For Well 4A.

Re-Analysis Results Previous Analysis Results*S sY Tm'/d S sYTes t Analysis

Const nt -RateI Pumping Test

Type 8 CurveAnalysis 254 NA 0.025 0.15 NA NA NA NAComplete Uncon-fined Aquifer 254 0.001Curve Analysis 0.025 0.10 269 0.0045 0.016 0.11

Slug InterferenceTest* 242 0.0005 0.028 0.14 763 NA 0.012 NA

***

Previous analysis reported in Swanson (1992)Previous analysis based on the fully penetrating confined aquifersolution method pre sented in Novakowski (1990); Re-analysis based onth e partial pene tration unconfined aquifer solution method presen tedin this letter report

NA Not Appl icabl e


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2. To: ( R e c e i v i n g O r g a n i z a ti o n ) 3. From: ( O r i g i n a t i n g O rg an i t a ti n) 4. Rel ated EDT No.: 17. Purchase Order No.:. cog. Engr.:

L . C. SwansonI Distribution I Geosciences I 1

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r SUPPORTING DO CUM ENT2. T i t l eRe-Analysis of Hydraul ic Tests Conducted forWell 4Aconstant-rate discharge test, slug interferencetest, diagnostic analysis, Type B curve analysis,unconfined aquifer type-curve analysi s

5. Key Words

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WHC.SD.EN.TI.260, Rev . 0CONTENTS

1.0 BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0 PUMPING TEST RE-ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . 1

2.1 DIAGNOSTIC ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . 22.2 TYPE B CURVE ANALYSIS . . . . . . . . . . . . . . . . . . . . . . 22.3 COMPL ETE UNCONFINED AQUIFER TYPE-CURVE ANALYSIS . . . . . . . . . 53.0 SLUG INTERFERENCE TEST RE-ANALYSIS . . . . . . . . . . . . . . . . . . 83.1 TYPE-CURVE ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . 113.2 SENSITIVITY ANALYSIS . . . . . . . . . . . . . . . . . . . . . . 134.0 SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.0 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21FIGURES:1 . Diagn ostic Drawdown and Drawdown Derivative Plot for Well 4A . . . . 3234 .5 .6

7 .8910.11 .12

Com bined Drawdown and Drawdown Derivative. Type B CurveSlug Test Response at Well 4T; Test Date April 14. 1992 . . . . . . . 7Analys is f or Well 4A . . . . . . . . . . . . . . . . . . . . . . . . 4Schema tic of Slug Test Double Straight-Line Effect . . . . . . . . . 9Combi ned Drawdown and Drawdown Deri vat ve . Compl ete Unconf nedAquifer Type-Curve Analysis for Well 4A . . . . . . . . . . . . . . . . 0Comparison of Pumping Test Drawdown and Drawdown Derivativesand Equivalent Head and Head Derivative Slug InterferenceTest Re sponse for Well 4A . . . . . . . . . . . . . . . . . . . . . . 12Unconfined Aq uifer Type-Curve Analysis for S1ug InterferenceSensi tivity o f Predicted Slug Interference Response for Well 4ASensi tivity o f Predicted Slug Interference Response for Well 4A

Sensi tivity o f Predicted Slug Interference Response for Well 4A

Test Re sponse for Well 4A . . . . . . . . . . . . . . . . . . . . . .to Varying Transmissivity . . . . . . . . . . . . . . . . . . . . . . 15to Varying Storativity . . . . . . . . . . . . . . . . . . . . . . . 16to Wellbore Storage Effects . . . . . . . . . . . . . . . . . . . . .

14

17Sensi tivit y of Predicted Slug Interference Response f or Well 4A. to Varying S/S, . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Sensit ivity of Predicted Slug Interference Response for Well 4A t oVarying& . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

i i i

. . ..... . . . .... . . . . . . ..... ... . . . ......... ...._ ., ., , , ...r.d?. T. WC.+ .y < < . . . f l W Y A -r .:,. c -. T.. ; .- :qy-. ; ,


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WHC-SD-EN-TI-260, Rev. 0

CONTENTS, (cont .TABLE:1. Comparison o f Hydr aul ic Tes t Ana lys is Resul ts f o r We l l 4 A . . . . . . 20

i v


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1.0 BACKGROUNDDuring 1992, a series o f hydrologic characterization tests wereconducted at th e well 4A - 4T test facility complex. Details concer ning thesetests are described in Swanson (1992). Two o f the tests, a constant-rate

discharge test conducted on March 30, 1992 and a slug interference testperformed on April 15, 1992, are the focus of this report.significant divergence in hydraulic property estimates (i .e., transmissivityand storativity/specific yield) obtained for the pumping test and sluginterferenc e test. The divergence in hydraulic property estimates is attri-buted to several deficiencies in the original slug interference analysis. Theoriginal slug interference test analysis was based on the procedure presentedi n Novakowski (1990), which is dependent on fully penetrating wells withinisotropic confined aqu ifer conditions. Subsequent to this analysis, analyti-cal methods have been developed, which provide the opportunity of extendingslug interference analysis t o a variety of test conditions including:

Preliminary analysis results presented in Swanson (1992) indicated a

Unconfined aquifersPartially penetrating wellsAnisotropic conditionsWellbore storage effects (for the pumped well).In addition, it is also noted that an incorrect stress level, i.e., H,value o f 0.536 m (1.76 ft), for the slug interference test was used in theoriginal analysis presented in Swanson (1992).As part o f the re-analysis effort, the results from the pumping testconducted at well 4T and observed at well 4A were re-examined. Whilesignificant changes were not expected from the pumping test re-analysis for

estimates of transmissivity and specific yield, a revised estimate forstorativity was anticipated; An amended value for storativity was expectedbecause th e original pumping test analysis method did not take into accountthe effects o f wellbore storage in observation well 4A. It is important tonote that t he storativity or elastic storage characteristics of the aquiferexert a strong influence on slug interference amp1 tude, as noted previouslyin Novakowski (1990) and Spane (1992). For these reasons, the pumping testresults f or well 4A were re-analyzed.

2.0 PUMPING TEST RE-ANALYSISTh e re-analysis procedure for th e drawdown portion of the pumping testat well 4A included the following analysis elements:

An initial diagnostic drawdown derivative analysisA late-time, Neuman Type B curve analysisA complete unconfined 'aquifer type-curve analysis ,including well bore storage effects.

1


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WHC-SD-EN-TI-260, Rev. 02.1 DIAGNOSTIC ANALYSIS

Combined drawdown and drawdown derivative plots have been shown to be apowerful diagnostic tool i n identifying operative flow conditions and factorsinfluencing drawd own during constant discharge pumping tests (e.g. , Bourdetet al. 1983, 1989; Spane 1993). Figure 1 shows the combined drawdown anddrawdown derivative plot for observation well 4A. The drawdown d erivativeswere calculated using the DERIV program described in Spane and Wurstner(1993).the foll owing operative flow conditions during the test were interpreted:.Based on a diagnostic analysis of the pattern exhibited in Figure 1,

Combined we1 1 bore storage and del ayed-yi el d responseconditions during the early phases of th e test (i.e.,up to =4 min)Unconfined aquifer, Type B curve response characteristicsbetween 4 and 5 00 minVari ab1 e drawdown/deri ati ve pattern after 500 mi n ,most 1 i kely attri butabl e to discharge fluctuations.

2.2 TYPE B CURVE'ANALYSISTo provide an initial estimate of transmissivity and specific yield,drawdown data during th e test period indicative of Neuman unconfined aquifer,Type B curve behavior were analyzed (i.e.? for test times 24 min). - T h ecombined Type B drawdown and drawdown derivative plot matching proceduredescribed in Spane (1993) was used in the test analysis. Drawdown type curveswere generated using the WTAQl program described by Moench (1993). Asdiscussed in Moench (1993), the WTAQl program runs faster and does not exhibitsome of the tes t instabilities that are sometimes exhibited with the DELAY2program descr ibed by Neuman (1975) for analysis of unconfined aqu ifer pumpingtests. Associated derivative plots of t he Type B curves were generated, asdiscussed previously, using the DERIV program.The combined drawdown and derivative plot match for the test is.shown in .Figure-2. As indicated in Figure 2, a very close match was obtained fo r thecombined drawdown and derivative plot for the identified test periodexhibiting Type B drawdown behavior (i.e., 24 min). Results of tg e analysisindicate ;stirnates for transmissivity and specific yield of 254 m /d(2,730 ft /d) and 0.025, respectively. A qualitative estimate fo r verticalanisotropy (K,) of 0.15 is also suggested. These results compare favorablywith preliminary unconfined aquifer analysis results for transmissivity(269 m2/d) , specific yield (0.016), and vertical anisotropy (0.11) reported inSwanson (1992) , which were obtained from automated type-curve analysis of theentire .drawdown record using t he ISOAQX program (HydraLogic 1989).


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0. o0 :9 :E - -

0 ) -w. L -O Ow o.-.-;Z?0 0 :

c -3 -00 -3 00 0L - r0 9 :

0 -

c -0 -c -0 -

,u

3 0

r ? :0 0 -0 0 -0 -L -

F i g u r e 1. Di ag no s t i c D rawdown and Drawdown De r i va t i ve P l o t ' for W e l l 4 A .

-

-

00

I 1 I I

c0 .0

9 I 1

xxxx

xXAa

Wel l 4 AD r a w d o w n D a t aD a t a D e r i v a t i v e

I - s p a c i n g = 0 . 2

discharge

wellbore storageeffects I--- ....-I_...--- r o = 9 . 1 7 m

r e w = 0 . 4 2 7 m0 = 9 2 . 7 L / m i n

0 . I 1 .o 10.0 100 .0 1000.0 10000.0T i m e , m i n

3


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9'0 .c

Figure 2. Combined Drawdown and Drawdown Derivative, Type B CurveAnalysis fo r Well 4 A .

1 I 1 1N e u m a n T y p e B W e l l 4 A- T y p e C u r v e x D r a w d o w n D a t a

c -z -0U2 0L - .

0 -- 0 -E -0 -E -0 -

0 0 -no:

3 0u o rs o :0 -*c0 .000

D e r i v a t i v e

.xxxx *.....*.

x x I /..f'.

0 ..e.*....'.e. -

.e...- Q = 9 2 . 7 L / m i n !- ......-;.... r o = 9 . 1 7 mr e w = 0 . 4 2 7 m

I I I I

C u r v e-.. ..T = 2 5 4 m 2 / d

S y = 0 . 0 2 5K D = 0.15

a D a t a D e r i v a t i v eL - s p a c i n g = 0.2

. 4


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WHC-SD-EN-TI-260, Rev. 02.3 COMPLET E UNCONFINED AQUIFER TYPE-CURVE ANALYSIS

An ad d i t i o n a l an a ly s i s was a l so a t temp ted t h a t an alyzed t h e e n t i r e tim edrawdown data s e t . The complete data analysis fol lowed the same procedure,descr ibed i n Sec t io n 2 .2 f o r t h e Type B cu r v e an a ly s i s .unconfined a qu i fe r an aly s i s p rocedure , however, inc lude s the ef fe c t s o fw e l l b o r e s t o r a g e , which would be expected t o be exh ib i te d dur ing th e e ar lyphases of the test . Wel lb o r e s t o r ag e e f f ec t s were accounted fo r , u t i l i z i n g anundocumented program that simulates well b o r e s t o r a g e e f f e c t s , which i s basedo n the procedure descr ibed i n Fenske (1977). The undocumented program can beused t o accou nt f o r pumping and observat ion w ellbore s tor ag e effects. Acomparison of results obta ined w i t h th e Fenske-based program indicated nearlyi d e n t i c a l results when compared w i t h p r ed i c t i v e r e sp o n ses ( i e. , f o r pumpingwe1 1 we1 1b o r e s t o r ag e ) g en e r a t ed w i t h th e Novakowski (1990) program f o rco n f in ed aq u i f e r s , an d th e program provided i n Dawson and Istok (1991) forunconf ined aq ui fe r Type A curve response.

The complete

To f u l l y ac c ou n t f o r t h e e f f e c t s o f w el lb o re s t o r a g e , t h e " e f f e c t i v e "well r a d iu s , re,,; for the pumped and observation wells i s r eq u i r ed . As willbe shown, t h e e f f e c t i v e w e ll r a d i u s for the pumped well 4T i s co n s id e r ab lyg r e a t e r t h a n f o r o b s e rv a t io n w ell 4A . The early-time drawdown pattern i n t h ev i c i n i t y o f t h e pumping well ( i . e . , w i t h i n a d i s t a n c e o f = l o0 w e l l b o r e r a d i i ) ,t h e r e f o r e , i s expected t o be af fe cte d more by pumping well ( r a t h e r t h anobservation we11) we1 1b o r e s t o r a g e e f f e c t s .

For wells w i t h san d/g rav e l p ack i n s t a l l a t i o n s , t h e e f f e c t i v e w e ll r ad iu scan b e ca l cu l a t ed u s in g t h e f o l l o w in g r e l a t i o n sh ip p r e sen t ed i n Bouwer (1989):

2re,,= [ ( l - n ) r c + n ryZlS

whererc = r ad iu s o f t h e w el l s c r eenr,, = r a d i a l d i s t a n c e from c e n t e r o f well t o the o u t s id e s an d /g r av e lpack.n = poros i ty o f the sand /gravel pack .For well 4A, given a well screen radius of 0.051 m (0 .1 66 7 f t ) , a r ad i a lgravel pack di s t an ce of 0 .102 m (0.333 f t ) , and an assumed porosity of 30%,y i e l d s a re,, f o r well 4A of 0.070 m (0.230 f t ) .A c a . l c u l a t i o n o f t h e r f o r th e pumped well (well 4T), however, i s mored i f f i c u l t b ec au se o f the "na tura l sand/gravel pack t h a t was developed aroundt h e well, dur ing previous wellbore developmental pumping. As noted i n Swanson( 1 9 9 2 ) , severa l bar re l s o f sand and s i l t were removed from well 4T d u r i n g t h edevelopm ental pumping pha se. The pre sen ce o f an extensive zone of "enhanced"permeabi l i ty su r rounding the immedia te wel lbore i s i n d i ca t ed a l so b y t h e

5


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WHC-SD-EN-TI-260, Rev. 0bi - l ine ar r esponse exh ib i t ed a t well 4T dur ing th e s l u g t e s t ( F i g u r e 3).means of es t imating possible v a lu es fo r t h e r , or w ell 4 1, t h e r ad i a ld i s t a n c e , rw, o th e o u t s id e boundary o f th e aeveloped "natur9 l sand /qravelpack calculated based on th e known disp lacement , V, = 0.027 m (0.96 f t ) andi n i t i a l stress r esponse , H = 0.168 m (0.55 f t ) observed a t wel l 4T dur ing th eApri l 14, 1992 s l u g test ( see F igure 3 ) . For this c a l c u l a t i o n , the fo l lowingre1 a t i onsh i p s were developed:

As a

whereV, = s l u g test volume displacement (0.027 m3)V, = displacement volume w i t h i n well screenV, = d i spl acement volume w i t h i n natural sand/gravel pack zone

where2V, = 71 rct H = 0.0067 m ; (0.237 f t 3 )

whererct = r ad iu s o f w e l l 4T well screen; 0.113 m (0.370 f t ) .Re-arranging Equation 2,

V = V, - V = 0.020 m3; (0.723 ft3)Also n o t e t h a t . f r o m a mo d i f i ca t i o n o f a r e la t ionsh ip in Bouwer (1989)

v, = n (r: - r)n H (3)For n v a lu es r an g in g from 15% t o 30%, c a l c u l a t e d . r values range between0.521 m t o 0.378 m (1.71 f t t o 1.24 f t ) , r e s p e c t i v e l y . k i n g these range o fr and n values in Equat ion 1 y i e l d s an e s ti m a te d e f f e c t i v e w ell r a d i u s , rew,o? 0.229 m (0.75 f t ) .The e f f e c t i v e well r ad iu s v a lu e o f 0.229 m would be expected t o provid ea v a l i d p r e d i c t i o n o f wellbore s t o r a g e e f f e c t s fo r t e s t c o n d i t i o n s w h e r e t h eh y d r a u l i c p r o p e r t i e s o f the n a tu r a l s and /gr ave l pack zon e a r e s i m i l a r t o t h a tof t h e su r r o u n d in g test fo rmat ion . However, as shown i n Figure 3, the "doubles t r a i g h t - l i n e p a t t e r n " d i s pl a y e d d ur in g t h e s l u g t e s t a t well 4T ind ica testh a t t h e d ev e lo p ed zon e ar ou nd t h e w el l p o s ses ses a s i g n i f i ca n t l y g r ea t e rt r a n s m i s s i v i t y t ha n the sur rounding fo rmat ion .g r e a t e r t r a n s m i s s i v i t y c a u s e s t h e s u r ro u nd in g t e s t f or m at io n r e s p on s e t o r e a c tT h i s developed inner zone o f

6


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WHC-SD-EN-TI-260, Rev. 0Figure3. Slug Test Response at Well 4T; Test Date: April 14, 1992(adapted from Swanson 1992).

projected yo = 0.156 ft (0.0475 m)I

o e o o o e e

4Time in minutes

7


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WHC-SO-EN-TI-260, Rev. 0more r a p i d l y . In th e pe t ro leum indu s t ry , wel l s w i t h inner zones o f enhancedp e r m e a b il i ty a r e r e f e r r e d t o as having a negat ive s k i n e f f e c t . A s i n d i c a t e dby Earlougher (1977), t h e e f f e c t i v e w e ll r a d i u s , rew, or w e l l s e x h i b i t i n gn e g a t i v e s k i n s i s g r e a t e r th a n t h e o b s er ve d o r c a l c u l a t e d w e ll r a d i u s , rw.

To es t im a te t h e " enh an ced" e f f e c t i v e w ell r ad i u s , reew, t w e ll 4T, ana n a l y s i s t e c h n i q u e p r e s e n t e d i n Bouwer (1989) was adapted. When doubles t r a i g h t - 1 ine co n d i t i o n s a r e ex h ib i t ed d u r in g s l u g t e s t i n g , Bo u w er (1989)s t a t e s t h a t t h e ob se rv ed i n i t i a l stress value (y,) should not be used i n t h ea n a l y s i s , b u t r a t h e r th e p r oj e ct e d i n i t i a l s t r e s s v al ue (y ) as shown i nFigure 4. The projected y, s t r e s s v a lu e i s what is actua l fy imposed on t h et e s t f o rm a t io n ( i . e . , o u t s i d e t h e i n n e r d ev elo pe d z on e o f enhanced permea-b i l i t y ) .known s l u g tes t s t r e s s vo!ume ( i .e . , slugg ing rod volume = 0.027 m ) can then

, be used i n the fol lowing re-ar rangement o f the volume equation for a c y l i n d e rt o prov ide an "enhanced" ef fe c t iv e wel l r a d i u s e s t i m a t e .The p r o j ec t e d y v a lu e o f 0.0475 m (0.156 f t ) from Figur; 3 and

Based on t h i s p r o ced ur e , a n I l r e w s t ima te o f 0.427 m (1.4 f t ) waso b ta in ed .t h e r e - a n a l y s i s o f t h e co n s t an t - r a t e pumping t e s t ( i e . , complete unconf inedaq u i f e r t yp e- cur v e an a ly s i s ) and s lu g i n t e r f e r en c e tes t .Figure 5shaw s t h e f i n a l r e s u l t o f matching the observed drawdown anddrawdown derivative w i t h a compl e t e unconf ined aqui f e r type curve and de ri va-t i v e p l o t . A s in di ca te d, a cl os e match was obtained for the combined drawdownand drawdown derivative p l o t . Resu l t s from the comple ted unconf ined aqu i ferc u r v e a n a l y s i s i n d i c a t f d the fo l1owJng hydrau l ic parameter es t imates :t r a n s m i s s i v i t y = 254 m /d (2,730 f t / d ) , s p e c i f i c y i e l d = 0.025, s t o r a t i v i t y =

0.001, an d v e r t i ca l an i so t r o p y = 0.10. . T h e s e r e s u l t s a r e v e r y s i m i l a r t or e s u l t s o b t a i n e d w i t h t h e T y p e B c u rv e a n a l y s i s a n d ' t o t h o s e p r e v i o u s l yreported by Swanson (1992). I t shou ld be noted, however, that the e s t i m a t efor s t o r a t i v i t y i s c on sid ere d t o b e v e r y q u a l i t a t i v e , p r imar i l y b ecau se o f t h e. l a c k o f e a rl y -t im e d a t a ( i . e . , t h e f i r s t 25 seconds) and the lack o f s e n s i -t i v i t y ' f o r smal l drawdown measurements (no te th e " s ta i r - s te ppe d" pa t te rn f o rdrawdowns t0.015 m ) .

T h i s e s t i m a t e for th e enhanced" ef fe c t iv e wel l r ad ius was used in

.

3.0 SLU G INTERFERENCE TEST RE-ANALYSISA s no ted i n Sec t io n 1.0, t h e o r i g in a l s lu g i n t e r fe r e n c e t e s t a n a l y s i s

was based on the an a ly s i s p r o ced u r e p r e sen t ed i n Novakowski (1990), which i sdependent on f u l l y p e n e t r a t i n g w e l l s w i t h i n i s o t r o p i c c o n f i n e d a q u i f e rco n d i t i o n s . Su b seq uen t t o th i s analys i s , ana ly t ica l methods have beendevel oped, which p r o v i d e t h e o p p o r t un i t y of e x t e nd in g s l u g i n t e r f e r e n c ea n a l y s i s t o a v a r i e t y o f t e s t c o n d i t i o n s i n c l u d i n g u n c o n f i n e d a q u i f e r s ,p a r t i a l l y p e n e t r a t i n g w e l l s , a n i s o t r o p i c c o nd i. ti on s, and w e ll b or e s t o r a g ee f f e c t s . The an a ly s i s ex t en s io n i s b ased o n a n a l y t i c a l d i s c u s s i o n s p r e s e n t e d

8


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WHC-SD-EN-TI-260, Rev. 0Figure 4. Schematic o f Slug Test Double Straight-Line Effect(adapted from Bouwer 1989).

4

0

9

t


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WHC-SD-EN-TI-260, Rev. 0F i g u r e 5. Combined Drakdown and Drawdown Deri v a t i ve, Compl e t e U nc onf ine dA q u i f e r T yp e-C urve A n a l y s i s f o r W e ll 4A .

0

T = 2 5 4 m 2 / ds = 0 . 0 0 1S y = 0 . 0 2 5K D = 0 . 1 0

0

We II.bor e S t o r a g e D r aw d ow n D a t aD a t a D e r i v a t i v e

D e r i v a t i v e C u r v e L - s p a c i n g = 0 .2

Q = 9 2 . 7 L / m i nr o = 9 . 1 7 rn

0.1 1 .o 10.0 1 0 0 . 0 1 0 0 0 . 0 1 0 0 0 0 . 0T i m e , m i n

10


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WHC-SD-EN-TI-260, Rev. 0i n Novakowski (1989), Peres (1989) , and Peres e t a l . (1989), which demonstratet h a t s l ug t e s t s can be r epresen ted as a specia l ized fo rm of cons tan t - r a tep ump i n g t e s t s . As noted i n Peres ( 1 9 89 ), t h e s l u g t e s t w e l lb o r e so lu t i o n canbe ' I . . . o b t a in e d d i r e c t l y from t h e ti m e d e r i v a t i v e o f t h e c o n s t a n t r a t ew e l lb o re s t o r a g e s o l u t i o n ... ( and tha t th is r e l a t i o n s h i p ) i s a l s o v a l i d forany res erv oir /w el l system and ho l ds a t an y p o s i t i o n w i t h i n t h e r e s e r v o i r . "

A d e t a i l ed d esc r ip t i o n o f t h e p r o ced u r es for s l u g t e s t c on v er si on i s notpresen ted here.a n a l yt ic a l j u s t i f i c a t i o n of t h e s l u g test conversion method.how ever, s l u g t e s t d a t a were conver ted t o equ ivalen t head (pumping t e s t )d rawdown data by in tegra t ing the observed s lug tes t head da ta over t h eo bs er ve d t e s t time, a s i n d i c a t e d i n Per es e t a l . ( 19 8 9) . M u l t i p l i c a t i o n o ft h e o b se r v ed s lu g test head data by the observed , t es t time y i e l d s thel o g a r i t h mic d e r iv a t i v e o f t h e eq u iv a l en t h ead chang e f o r a co n s t an t - r a t epumping tes t .response observed a t wel l 4A d u r i n g t h e c o n s t a n t - r a t e pumping t e s t w i t h t h econver ted equivalent head and head der ivat ive response obtained dur ing thes l u g i n t e r f e r e n c e test . As i n d i ca t ed i n Figure 6 , s i m i l a r p a t t e r n s h a p e s a r ee x h i b i t e d .. t h e tw o tes ts need t o be normalized.

The reader s h o u l d consu l t the aforement ioned references f o rB r i e f ly s t a t e d ,.

Figure 6 shows a comparison o f the drawdown and drawdown derivative

To equate t h e two t e s t r e sp o ns e s, however, t h e s t r e s s l e v e l s f o rAs noted i n - Novakowski (1989) and Peres e t a l . ( 1 9 8 9 ) , the i n s t an t an eo u sd i s c h a r g e r a t e , Qi., (gal / min ) , imposed by a s lu g t e s t can be ca lc ul at edd i r e c t l y by the d spl acement volume, V,.0.027 m (0.96 f t ), a Qi value of 27.2 L /m i n (7.18 gal/min) i s i n d i c a t e d . Tonormalize the s lu g t e s t d e r iv ed r e su l t s t o t h e d rawdown o b se rv ed d u r i n g t h econstant- rate pumping t es t , th e eq ui va le nt head drawdown da ta were mu1 t i p 1 iedby a f a c to r o f 3 .4 1 , w hich r ep r ese n t s t h e r a t i o o f t h e two d is ch a r g e r a t e s(i .e. , 92.7 L/min/27.2 L/min). As indicated by the normalized equivalent headrespon se, a c lo s e correspondence between t he pumping t e s t drawdown andequivalen t head /s lug , tes t r e s u l t s i s i n d i c a t e d .t h e t ime p e r io d o f s l i g h t drawdown d ep a r tu r e ( i . e . , a f t e r =7 min) r e p r es en t s a, t ime p e r io d d u r in g the t e s t when the s lug i n te r fe ren ce r esponse had decayed t oa value of 0.0006 m (0.002 f t ) or l e s s .s h o u l d be placed on this s l i g h t d e v i a t i o n .

For a d i spl acement vol ume' o f

I t sho u ld a l so be n o ted t h a tNo g r e a t s i g n if i c a n c e , t h e r e f o r e ,

3 . 1 TYPE-CURVE ANALYSISFor genera t ing p red ic ted s l u g in ter ference unconf ined aqu i fer typec u r v e s f o r the g iven w e ll s i t e t e s t co n d i t i o n s , p r ed i c t ed p umping tes t draw-down curves were f i r s t generated using the WTAQl program, using given tes ts i t e c o n d i ti o n s ( e. g. , r , Q, re ) and se lec ted hydrau l ic parameter va lues(e .g . , T, S, S,, ) . E f f e c t s O F wellbo re s tor ag e were accounted for u s i n g

method. Drawdown d e ri v a ti v e s were ca lc ul at ed u s i n g t h e DERIV pro grampresen ted i n Spane and Wurstner (1993). S l u g in ter ference r esponses were theng en e r a t ed b y d iv id in g t h e ca l cu l a t ed pumping t e s t d e r i v a t i v e by t h e t e s t t ime.The well 4A t e s t respo nse was analyzed by matching th e gene rate d s lu g inter-f e re n c e t y p e c u r v e s t o the observed s l u g i n t e r f e r e n c e d a t a .an a ly s i s p r o ced u re con t in u ed i t e r a t i v e l y by v ar y in g t h e v a lu e f o r i n p u tparameters T , S , S,, and u n t i l a v i sua l ly accep tab le match was ob ta ined .

the program descr i 9ed i n Sect ion 2 .3 , which i s based on the Fenske (1977)The type-curve

11


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WHC-SD-EN-TI-260, Rev. 0Figure 6. Comparison o f Pumping Test Drawdown and Drawdown Derivatives andEquivalent Head and Head Derivative Slug InterferenceTest Response for Well 4 A .

00

0 E q u i v a l e n t H e a d a D r a w d o w n Derivative6 E q v . H d . .Derivative L - s p a c i n g = 0.2

N o r m a l i z e d R e s p o n s e

' ro = 9 . 1 7 mr e w = 0.427 m

0 p u m p = 92.7 L / m i

0.0 1 0 . 1 0 1 .oo 10 .00 1 0 0 .0 0 1000.T i m e , m i n 0 0


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WHC-SD-EN-TI-260 , Rev. 0Figure 7shows the resulting best-fit unconfined aquifer type curve

Less emphasis was placed on matching late-time (i.e., 27 min),match.response in the central portion (i.e., th e " h u m p " ) of the slug interferenceresponse.because of th e extremely small (i.e., 10.0006 m) and somewhat erratic natureof the observed measurements. As indicated in Figure 7, a close match wasobtained fo r most of t he observed slug interference response.analysis Indicate est imates f or transmissivity and storativity o f 242 m /d(2,600 ft /d) and 0.0005, respectively. A more qualitative estimate f orvertjcal anisotropy ( ) of 0.14 and for specific yield of 0.028 is alsounconfined aquifer type-curve analyses presented i n Sections 2.2 and 2.3.

Emphasis in the analysis was primarily placed on matching the observed

Results ff the

suggested. These resu s compare favorably with results obtained from the

3.2 SENSITIVITY ANALYSISSlug interference test response is a function of the applied stress,test well/ aquifer relationships (i.e.? well diameter, radial distance,.aqu iferthickness, we1 1 penetration characteristics) and test formation hydraulicproperties (i.e., T, S, S,, .and fd). If it is assumed that the applied stress

and test well/aquifer relationships are known for the test, an infini te numberof predictive response shapes are still possible. The number of predictiveresponses can be greatly reduced, however, if expected (common) bounds can beapplied for som e of th e formation hydraulic properties. Limits used for sluginterference type curves generated for th e analysis,of the well 4A t estresponse incl$d$d S, = 0.005 t o 0.4, S =T = 10' to 10 m /d (10' to lo5 ft'/d) . to 10- , fd = 0.01 to 1.0, andTo exam ine th e sensitivity of the predicted slug interference response

Figures 8

The

to vari ous hydraul c property combinations, individual type curves weregenerated by systematically varying selected parameter estimates.through 12 sho w the results o f the sensitivity analysis. A s expected,variation in the selected hydraulic property values causes significan t changesi n the'shape and amplitude of the predicted slug interference response.following general observations are provided that summarize the sensitivity o fthe predicted slug interference response to hydraul ic property v ariation(i.e., given well 4A test sit e conditions).

0

e

Transmiss ivity is the principal parameter control1 ing th etransmission ( i .e. , arrival time) of the interference response(Figure 8).Storativity exerts a significant influence on the am plitudeand shape of the initial slug interference "hump" (Figures 9and 10).Wellbore storage effects dampen and delay transmission of th einitial slug interference response observed (Figure 10).

13


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WHC-SD-EN-TI-260, Rev. 0Figure 7 . Unconfined Aq uif er Type-Curve An aly sis for S1ug I n t e r f e r e n c eTest Response for Well 4A .

00OCc I 1 I0 . U n c o n f i n e d A q u i f e r- T y p e C u r v eW e l l b o r e S t o r a g e0E E -.? :

ale.l n -c0 -n .ln

T = 2 4 2 m 2 / dS = 0 . 0 0 0 5 '

S / S y = 0 . 0 1 8K D = 0 . 1 4

x W e l l 4 A T e s t D a t ar o = 9 . 1 7 rn

r e w = 0 . 4 2 7 mr w m = 0 . 0 7 0 m

Ho = 0 . 0 4 8 m

alE0,

=Ilnln

L

@ En ?L O

0

c000' 0

0 .0 1 0 . 1 0 1 . o o 1 0 .0 0 1 0 0 . 0 0T i m e , m i n

14


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We -WL -3InIn 0L O - , '

0 :0

c000

Figure, 8 . Sensitivity o f Predicted Slug Interference Response for Well 4 A toVarying Transmissivity (S = 0.0005, S / S , = 0.018, = 0.14) .

/

, #'/',

1

F i n a l S o l u t i o n-I I I-r

S e n s i t i v i t y A n a l y s .T = 50 m 2 / dT = 1 0 0 0 m 2 / dS = 0.0005

s / S y = 0 . 0 1 8K D = 0 . 0 1 4

X W e l l 4 A T e s t D,otar o = 9 . 1 7 m

r e w = 0 , 4 2 7 mr w m = 0 . 0 7 0 rn

H o = 0 . 0 4 8 m

0 . 0 1 0.10 1 . o o 10.00T i m e , r n i n

15

1 0 0 . 0 0


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WHC-SD-EN-TI-260, Rev. 0Figure9. Sensitivity of Predicted Sluq Interference Response for Well 4A toVarying Storativity (T = 242 m /d, S/S, = 0.018, I$ = 0.14)(well ore storage effects are included) .

00

s = 0 . 0 0 0 1s = 0 . 0 0 1 r o = 9 . 1 7 mr e w = 0 . 4 2 7 rn

T = 2 4 2 m 2 / d r w m = 0 . 0 7 0 mS / S y = 0 . 0 1 8 H o = 0 . 0 4 8 m

K D = 0 . 0 1 4

F i n a l S o l u t i o n00 1 1 1

0 . 0 1 0 . 1 0 1 . o o 1 0 . 0 0 100.00T i m e , m i n

16


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WHC-SD-EN-TI-260, Rev. 0Figure 10. Sensitivity of Predicted Slug interference Response for Well 4A toWellbore Storage Effects (T = 242 m /d, S/S, = 0.018, = 0 .14) .

000

0 .?': I I 1 ILine Source Sol ution W e l l 4 A T e s ts = 0 . 0 0 0 1 C o n d i t i o n sc -

0.00 0 . 0 1 0 0 .1 0 0 1 .0 0 0 1 0 .0 0 0 1 0 0 . 0 0 0T i m e , m i n


39/43


Figure 11 . Sensitivity of Predicted >lug Interference Response for Well 4A toVarying S/S, (T = 242 m /d, S = 0.0005, = 0.14) .

000 I 1 Ic0 S e n s i t i v i t y A n a l y s . x Well 4 A T e s t D a t a

T- = 2 4 2 m 2 / dS' = 0 . 0 0 0 5

K D = 0 . 1 4

r o = 9 . 1 7 mr e w = 0 . 4 2 7 mr w m . = 0 . 0 7 0 mH o = 0 . 0 4 8 m

aJ-txaJLaininaLa

0 . 0 1 0.10 1.00T i m e , m i n

18

10.00 1 0 0 .0 0


40/43

WHC-SD-EN-TI-260 , Rev. 0

9 -

0 E -

Figure 12. Sensitivity o f Predictzd S l u g Interference Response fo r Well 4A to(T = 24 2 m /d, S = 0.0005, S/S, = 0.018).arying

L

000c 1 I IS e n s i t i v i t y A n a l y s .

K D = 0 . 0 5K D = 0.5T ' = 2 4 2 m 2 / dS = 0.'0005

S / S y = 0 . 0 1 8

x W e l l 4 A T e s t D o t or o = 9 . 1 7 m

r e w = 0 . 4 2 7 mr w m = 0 . 0 7 0 mH o = 0 . 0 4 8 m

F i n a l S o l u t i o n0 . 0 1 0.10 1 - 0 0 1 0 . 0 0 IOO.00

T i m e , r n i n

19


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0.0250.025

0.028

The s t o r a t i v i t y / s p e c i f i c y i e l d r a t i o a f f e c t s p r im a r il y t h es l ope o f t he r e c e s s i ona l l i m b o f t h e i n i t i a l s l u g i n t e r f e r e n c eI I hump" response (F igure 11).

0.150.10

0.14

V e r t ic a l a n i s ot ro p y , l i k e s t o r a t i v i t y , e x e r t s a s i g n i f i c a n tinf luence on the ampl i tude and shape of the i n i t i a l s l u gi n t e r f e r e nc e r e s pons e (F igure 12); however, t h e predominant regiono f i n f l ue nc e i s the peak ampli tude and recess ional l i m b of t hei n t e r f e r e nc e r e s pons e .

4.0 SUMMARY

A general procedure i s ou t l i ne d for genera t ion o f s l u g i n t e r f e r e n c e t e s tresponses wi th in an i so t ropic , unconf ined aqui fe rs w i t h p a r t i a l l y p e n e t r a t i n gwe1 1 con f igu ra t io ns . The procedure i s based on convers ion o f av at l ab1 eunconfined a qu if er co ns tan t-r a te pumping t e s t type curves , which have beenm o dif ie d t o a c co u nt f o r t h e a f f e c t s o f pumping wel l we l lbore s torage .o f s e n s i t i v i t y a na l ys e s in d i c a te d t h a t v a r i a t i o n s i n T, S, S y ,n i f i c a n t i n f l ue nc e ( i n vary ing de g re e s ) on th e t ran sm iss io n, amp i tu de , andshape of t h e s l u g i n t e r f e r e nc e r e s pons e .Resul t s

7 exert sig-A comparison o f hydraul i c proper ty es t imates obta ined f rom the re -a n a l y s i s o f t h e c o n s t a n t - r a te pumping and s l u g i n te r f er e n c e t e s t s (shown i nTable 1) in d i ca te s a c lo se cor respondence . The c lo se cor respondence i nhy dra u l i c p rope r t y e s t i ma t e s s ugge s t s t ha t s l u g i n t e r f e r e n c e t e s t s c a n p r o v i d es i m i l a r c h a r a c t e r i z a t i o n r e s u l t s , un der f a v o ra b le t e s t c o n d i t io n s .

Table 1. Comparison of Hydraulic Test Analysis Results for Well 4A.T e s t a n a l y s i s

C ons t a n t - r a t epumping t e s tType B c u rvea n a l y s i sCompleteunconf i neda q u i f e r c u r v ea n a l y s i s

S l u g i n t e r -f e r e n c e t e s t ba p re v i ous a nbPrevious ans o l u t i o n method pp a r t i a1 p e n e t r a t idocument.NA = no t. app

Re-analysi s r e s u l t si; 1 0 . 1 10.000

Previous anal .Tm2/d

NA269

763

S

NA0.0045

NA

; i s r e s u l t s a

NA0.016

0.012i l y s i s r e p o r t e d i n Swanson (1992).i ly s i s based o n t h e f u l l y p e n e t r at i n g c o n fi ne d a q u i f e rpesented in Novakowski (1990); re-analys is based on the3n unconfined aquifer s o l u t i o n method presented i n t h i s1 i cab1 e .

20

-KO

NA0.11

NA


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'WHC-SD-EN-TI-260 , Rev. 0

5.0 REFERENCESBourdet D. T. M. Whittle, A. A. Douglas, and Y. M. Pirard 1983, "A New Set

0 , Type Curves Simplifies Well Test Analysis," Wor7d ~ i 7 ,ay: 95-106.Bourdet, D., J. A. Ayoub, and Y. M. Pirard, 1989, "Use of Pressure Derivativein Well-Test Interpretation," SPE Format ion Eva7uat ion, Jun e 1989:293-302.Bouwer, H., 1989, "The Bouwer and Rice Slug Test - An Update," Ground Water,Vol. 27, no. 3.Cooper, H. H. , Jr. , J. D. Bredehoeft, and I. S. Papadopulos, 1967, "Responseof a Finite-Diameter Well to an Instantaneous Charge of Water," WaterResources Research, 3 (1) : 63-269.Dawson, K. J. and J. D. Istok, 1991, Aq u i f e r Te s t i ng : Des ign and Ana7ys is o fPumping and S7ug Tests, Lewis Publishers, Inc. , Chelsea, Michigan.Earlougher, R. C., Jr., 1977, Advances i n We77 Te st An a7 ysis , Henry L. DohertyFenske, P. R., 1977, "Radial Flow with Discharging-Well and Observation-WellHorn, R. N. , 1990, Modern We77 Test Ana7ysis: A Computer-Aided Approach,

Series, Monograph Volume 5, SOC. of Pet. Engineers, A I M E .Storage, t Journa7 o f Hydro7ogy, 32:87-96.Petroway, Inc. , Palo Alto, California; distributed by SOC. Pet. Engrs. ,Richf el d, Texas.

HydraLogic, 1989, ISOAQX: Opera t ions Gu ide, Hydralogic, Missoul a, Montana.Moench, A. F., 1993, "Computation of Type Curves for Flow to Partially.Penetrating Wells in Water-Table Aquifers," Ground Water, 31(6) :966-971.Neuman, S. P., 1975, "Analysis of Pumping Test Data from Anisotropic Uncon-Water Resourcesined Aquif ers Considering Delayed Gravity Response,Research, 11(2):329-342.Novakowski , K. S. , 1989, "Analysis of Pulse Interference Tests, WaterResources Research, 25 11) : 377-2387.Novakowski, K. S., 1990, "Analysis of Aquifer Tests Conducted in FracturedRock: A Review o f th e Physical Background and the Design of a ComputerProgram f or Generating Type Curves," Ground Water, 28(1):99-105.Peres, A. M., 1989, "Analysis of Slug and Drillstem Tests," unpublished Ph.D.'dissertation, University o f Tulsa, Tulsa, Oklahoma.Peres, A. M., M. Onur, and A. C. Reynolds, 1989, "A New Analysis Procedure ForDetermining Aquifer Properties from Slug Test Data,Research, 25(7):1591-1602. Water Resources

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.' .WHC-SD-EN-TI-260, Rev. 0

Reed, J . E . , 1980, ''Type Curves fo r Sele cte d Problems of Flow to W ells i n 'Confined Aquifers, 'I i n Techniques o f Water-Resources Investigations,Book 3 , Cha pter 83, U.S. G eological Survey.Spane, F. A . , Jr . , 1992, Applicability o f Slug Interference Tests Unde rHanford Site Test Conditions: Analytical Assessment and Field Test

Eva7uation, PNL-8070, P a c if ic Northwest Lab oratory , Richl and,Washington .' Spane, F. A. , Jr. , 1993, Se7ected Hydraulic Test Ana7ysis Techniques f o rConstant-Rate Discharge Tests, PNL-8539, P a c if i c Northwest Labo rato ry,Richl and, Washington.

Spane, F. A . , Jr. , and S. K. Wurstner, 1993, "DERIV: A Program for Calcu l a t -i n g P r es su r e D er iv a t i v es f o r Use i n Hydraulic Test A n alys i s , " GroundWater, 31(5) :814-822; a l s o as PNL-SA-21569, P a c i f i c Northwe stLaboratory, Richland, Washington.Swanson, L. C., '1992, Phase 1 Hydrogeologic Summary o f the 300-FF-5 Operable

Unit, 300 Area, WHC-SD-EN-TI-052, Rev. 0 , Westinghouse Hanford Company,Richl and, Washington.I

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Re-Analysis of Hydraulic Tests