ASTM_D_4630_-_96_2008.pdf

Designation:D463096(Reapproved 2008)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 D4630;the number immediately following the 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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers a 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 the 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 asstandard.No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated 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 transmissivity 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 kg/(2)where:=fluid density,=fluid viscosity,andg=acceleration due to gravity.2.1.2 storage coeffcient,Sthe 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:Ss5 gCb1nCw!(4)where:Cb=bulk rock compressibility,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 is the predominant usage in groundwa-ter 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(L3T1).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).1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved Sept.15,2008.Published October 2008.Originallyapproved in 1986.Last previous edition approved in 2002 as D4630 96(2002).DOI:10.1520/D4630-96R08.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.2.15 nporosity(dimensionless).2.2.16 rwradius of test hole(L).2.2.17 ttime elapsed from start of test(T).2.2.18 dimensionless parameter.2.2.19 viscosity of water(ML1T1).2.2.20 density of water(ML3).3.Summary of Test Method3.1 Aborehole 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.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 changes 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 contained 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:(1)it avoids the effect ofwell-bore storage,(2)it may be employed over a wide range ofrock mass permeabilities,and(3)it is considerably shorter induration than the conventional pump and slug tests used inmore permeable rocks