ASTM D4630-1996(2002) Standard Test Method for Determining Transmissivity and Storage Coefficient of Low-Permeability Rocks by In Situ Measurements Using the Constant Head Injectio.pdf

1、Designation: D 4630 96 (Reapproved 2002)Standard Test Method forDetermining Transmissivity and Storage Coefficient of Low-Permeability Rocks by In Situ Measurements Using theConstant Head Injection Test1This standard is issued under the fixed designation D 4630; the number immediately following the

2、designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a

3、 field procedure for determin-ing the transmissivity and storativity of geological formationshaving permeabilities lower than 103m2(1 millidarcy) usingconstant head injection.1.2 The transmissivity and storativity values determined bythis test method provide a good approximation of the capacityof th

4、e zone of interest to transmit water, if the test intervals arerepresentative of the entire zone and the surrounding rock isfully water-saturated.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety concerns, if any, assoc

5、iated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 transmissivity, Tthe transmiss

6、ivity of a formation ofthickness, b, is defined as follows:T 5 Kb (1)where:K = hydraulic conductivity.The hydraulic conductivity, K, is related to the permeability,k, as follows:K 5 krg/ (2)where:r = fluid density, = fluid viscosity, andg = acceleration due to gravity.2.1.2 storage coeffcient, Sthe

7、storage coefficient of aformation of thickness, b, is defined as follows:S 5 Ssb (3)where:Ss= specific storage.The ebrss is the specific storage of a material if it werehomogeneous and porous over the entire interval. The specificstorage is given as follows:Ss5rg Cb1 nCw! (4)where:Cb= bulk rock comp

8、ressibility,Cw= fluid compressibility, andn = formation porosity.2.2 Symbols:2.2.1 Cbbulk rock compressibility (M1LT2).2.2.2 Cwcompressibility of water (M1LT2).2.2.3 Gdimensionless function.2.2.4 Khydraulic conductivity (LT1).2.2.4.1 DiscussionThe use of symbol K for the termhydraulic conductivity i

9、s the predominant usage in groundwater literature by hydrogeologists, whereas the symbol k iscommonly used for this term in the rock and soil mechanicsand soil science literature.2.2.5 Pexcess test hole pressure (ML1T2).2.2.6 Qexcess water flow rate (L3T1).2.2.7 Qomaximum excess water flow rate (L3T

10、1).2.2.8 Sstorativity (or storage coefficient) (dimensionless).2.2.9 Ssspecific storage (L1).2.2.10 Ttransmissivity (L2T1).2.2.11 bformation thickness (L).2.2.12 efracture aperture (L).2.2.13 gacceleration due to gravity (LT2).2.2.14 kpermeability (L2).2.2.15 nporosity (dimensionless).2.2.16 rwradiu

11、s of test hole (L).2.2.17 ttime elapsed from start of test (T).1This test method is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.21 on Ground Water andVadose Zone Investigations.Current edition approved Oct. 10, 1996. Published Jun

12、e 1997. Originallypublished as D 4630 86. Last previous edition D 4630 86 (1991)e1.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2.18 adimensionless parameter.2.2.19 viscosity of water (ML1T1).2.2.20 rdensity of water (ML3).3. Su

13、mmary of Test Method3.1 A borehole is first drilled into the rock mass, intersectingthe geological formations for which the transmissivity andstorativity are desired. The borehole is cored through potentialzones of interest, and is later subjected to geophysical boreholelogging over these intervals.

14、 During the test, each interval ofinterest is packed off at top and bottom with inflatable rubberpackers attached to high-pressure steel tubing.3.2 The test itself involves rapidly applying a constantpressure to the water in the packed-off interval and tubingstring, and recording the resulting chang

15、es in water flow rate.The water flow rate is measured by one of a series of flowmeters of different sensitivities located at the surface. Theinitial transient water flow rate is dependent on the transmis-sivity and storativity of the rock surrounding the test intervaland on the volume of water conta

16、ined in the packed-off intervaland tubing string.4. Significance and Use4.1 Test MethodThe constant pressure injection testmethod is used to determine the transmissivity and storativityof low-permeability formations surrounding packed-off inter-vals. Advantages of the method are: (a) it avoids the e

17、ffect ofwell-bore storage, (b) it may be employed over a wide range ofrock mass permeabilities, and (c) it is considerably shorter induration than the conventional pump and slug tests used inmore permeable rocks.4.2 AnalysisThe transient water flow rate data obtainedusing the suggested test method a

18、re evaluated by the curve-matching technique described by Jacob and Lohman (1)2andextended to analysis of single fractures by Doe et al. (2). If thewater flow rate attains steady state, it may be used to calculatethe transmissivity of the test interval (3).4.3 Units:4.3.1 ConversionsThe permeability

19、 of a formation isoften expressed in terms of the unit darcy. A porous mediumhas a permeability of 1 darcy when a fluid of viscosity 1 cp (1mPas) flows through it at a rate of 1 cm3/s (106 m3/s)/1 cm2(104 m2) cross-sectional area at a pressure differential of 1atm (101.4 kPa)/1 cm (10 mm) of length.

20、 One darcy corre-sponds to 0.987 m2. For water as the flowing fluid at 20C, ahydraulic conductivity of 9.66 m/s corresponds to a perme-ability of 1 darcy.5. ApparatusNOTE 1A schematic of the test equipment is shown in Fig. 1.5.1 Source of Constant PressureA pump or pressureintensifier shall be capab

21、le of providing an additional amountof water to the water-filled tubing string and packed-off testinterval to produce a constant pressure of up to 1 MPA (145psi) in magnitude, preferably with a rise time of less than 1 %of one half of the flow rate decay (Q/Qo= 0.5).5.2 PackersHydraulically actuated

22、 packers are recom-mended because they produce a positive seal on the boreholewall and because of the low compressibility of water they arealso comparatively rigid. Each packer shall seal a portion of theborehole wall at least 0.5 m in length, with an applied pressureat least equal to the excess con

23、stant pressure to be applied tothe packed-off interval and less than the formation fracturepressure at that depth.5.3 Pressure TransducersThe pressure shall be measuredas a function of time, with the transducer located in thepacked-off test interval. The pressure transducer shall have anaccuracy of

24、at least 63 kPa (60.4 psi), including errorsintroduced by the recording system, and a resolution of at least1 kPa (0.15 psi).5.4 Flow MetersSuitable flow meters shall be providedfor measuring water flow rates in the range from 103cm3/s to103cm3/s. Commercially available flow meters are capable ofmea

25、suring flow rates as low as 102cm3/s with an accuracy of61 % and with a resolution of 105cm3/s; these can testpermeabilities to 103md based on a 10-m packer spacing.Positive displacement flow meters of either the tank type(Haimson and Doe (4) or bubble-type (Wilson et al. (3) arecapable of measuring

26、 flow rates as low as 103cm3/s; these cantest permeabilities to 104md based on a 10-m packer spacing.5.5 Hydraulic SystemsThe inflatable rubber packers shallbe attached to high-pressure steel tubing reaching to the2The boldface numbers in parentheses refer to the list of references at the end ofthis

27、 standard.FIG. 1 Equipment SchematicD 46302surface. The packers themselves shall be inflated with waterusing a separate hydraulic system. The pump or pressureintensifier providing the constant pressure shall be attached tothe steel tubing at the surface. A remotely controlled down-holevalve, located

28、 in the steel tubing immediately above the upperpacker, shall be used for shutting in the test interval and forinstantaneous starting of tests.6. Procedure6.1 Drilling Test Holes:6.1.1 Number and OrientationThe number of test holesshall be sufficient to supply the detail required by the scope ofthe

29、project. The test holes shall be directed to intersect majorfracture sets, preferably at right angles.6.1.2 Test Hole QualityThe drilling procedure shall pro-vide a borehole sufficiently smooth for packer seating, shallcontain no rapid changes in direction, and shall minimizeformation damage.6.1.3 T

30、est Holes CoredCore the test holes through zonesof potential interest to provide information for locating testintervals.6.1.4 Core DescriptionDescribe the rock core from thetest holes with particular emphasis on the lithology and naturaldiscontinuities.6.1.5 Geophysical Borehole LoggingLog geophysic

31、allythe zones of potential interest. In particular, run electrical-induction and gamma-gamma density logs. Whenever possible,also use sonic logs and the acoustic televiewer. Run other logsas required.6.1.6 Washing Test HolesThe test holes must not containany material that could be washed into the pe

32、rmeable zonesduring testing, thereby changing the transmissivity and storat-ivity. Flush the test holes with clean water until the return isfree from cuttings and other dispersed solids.6.2 Test Intervals:6.2.1 Selection of Test IntervalsDetermine test intervalsfrom the core descriptions, geophysica

33、l borehole logs, and, ifnecessary, from visual inspection of the borehole with aborescope or TV camera.6.2.2 Changes in LithologyTest each major change inlithology that can be isolated between packers.6.2.3 Sampling DiscontinuitiesDiscontinuities are oftenthe major permeable features in hard rock. T

34、est jointed zones,fault zones, bedding planes, and the like, both by isolatingindividual features and by evaluating the combined effects ofseveral features.6.2.4 Redundancy of TestsTo evaluate variability in trans-missivity and storativity, conduct three or more tests in eachrock type, if homogeneou

35、s. If the rock is not homogeneous, thesets of tests should encompass similar types of discontinuities.6.3 Test Water:6.3.1 QualityWater used for pressure pulse tests shall beclean, and compatible with the formation. Even small amountsof dispersed solids in the injection water could plug the rockface

36、 of the test interval and result in a measured transmissivityvalue that is erroneously low.6.3.2 TemperatureThe lower limit of the test water tem-perature shall be 5C below that of the rock mass to be tested.Cold water injected into a warm rock mass causes air to comeout of solution, and the resulti

37、ng bubbles will radically modifythe pressure transient characteristics.6.4 Testing:6.4.1 Filling and Purging SystemOnce the packers havebeen set, slowly fill the tubing string and packed-off intervalwith water to ensure that no air bubbles will be trapped in thetest interval and tubing. Close the do

38、wnhole valve to shut in thetest interval, and allow the test section pressures (as determinedfrom downhole pressure transducer reading) to dissipate.6.4.2 Constant Pressure TestPressurize the tubing, typi-cally to between 300 and 600 kPa (50 to 100 psi) above theshut-in pressure. This range of press

39、ures is in most casessufficiently low to minimize distortion of fractures adjacent atthe test hole, but in no case should the pressure exceed theminimum principal ground stress. It is necessary to providesufficient volume of pressurized water to maintain constantpressure during testing. Open the dow

40、n-hole valve, maintainthe constant pressure, and record the water flow rate as afunction of time. Then close the down-hole valve and repeatthe test for a higher value of constant test pressure. A typicalrecord is shown in Fig. 2.7. Calculation and Interpretation of Test Data7.1 The solution of the d

41、ifferential equation for unsteadystate flow from a borehole under constant pressure located inan extensive aquifer is given by Jacob and Lohman (1) as:3Q 5 2pTP Ga!/rg, (5)where:Q = water flow rate,T = transmissivity of the test interval,P = excess test hole pressure,r = water density,g = accelerati

42、on due to gravity, andG(a) = function of the dimensionless parameter a:a5Tt/Srw2(6)where:t = time elapsed from start of test,S = storativity, andrw= radius of the borehole over the test interval.7.1.1 In Fig. 2, the flow rate in the shut-in, packed-offinterval is considered constant. In those cases

43、where theresponse of the shut-in interval is time dependent, interpreta-tion of the constant pressure test is unaffected, provided thetime dependency is linear.7.2 To determine the transmissivity, T, and storativity, S,data on the water flow rate at constant pressure as a function oftime are plotted

44、 in the following manner (1).7.2.1 First, plot a type curve log of of the function G (a)versus a where values of G (a) are given in Table 1.7.2.2 Second, on transparent logarithmic paper to the samescale, plot values of the log of flow rate, Q, versus values of thelog of time, t at the same scale as

45、 the type curve.7.2.3 Then, by placing the experimental data over thetheoretical curve, the best fit of the data to the curve can bemade.3For bounded aquifers the reader is referred to Hantush (5).D 463037.2.4 Determine the values of transmissivity, T, and storat-ivity, S, using Eq 5 and Eq 6 from t

46、he coordinates of any pointin both coordinate systems.8. Report8.1 The report shall include the following:8.1.1 IntroductionThe introductory section is intended topresent the scope and purpose of the constant pressure testprogram, and the characteristics of rock mass tested.8.1.1.1 Scope of Testing

47、Program:8.1.1.1.1 Report the location and orientation of the bore-holes and test intervals. For tests in many boreholes or in avariety of rock types, present the matrix in tabular form.8.1.1.1.2 Rationale for test location selection, including thereasons for the number, location, and size of test in

48、tervals.8.1.1.1.3 Discuss in general terms limitations of the testingprogram, stating the areas of interest which are not covered bythe testing program and the limitations of the data within theareas of application.8.1.1.2 Brief Description of the Test IntervalsDescriberock type, structure, fabric,

49、grain or crystal size, discontinui-ties, voids, and weathering of the rock mass in the testintervals. A more detailed description may be needed forcertain applications. In a heterogeneous rock mass or forseveral rock types, many intervals may be described; a tabularpresentation is then recommended for clarity.8.1.2 Test Method:8.1.2.1 Equipment and ApparatusInclude a list of theequipment used for the test, the manufacturers name, modelnumber, and basic specifications for each major item, and thedate of