1、Designation:D464508Standard Test Method forDetermination of In-Situ Stress in Rock Using HydraulicFracturing Method1This standard is issued under the fixed designation D4645;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、 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.Scope*1.1 This test method covers the determination of the in-situstate of stress in rock by hydraulic fracturing.NOTE1Hydraulic fr
3、acturing for stress determination is also referredto as hydrofracturing,and sometimes as minifracing.Hydraulic fracturingand hydrofracturing may also refer to fracturing of the rock by fluidpressure for the purpose of altering rock properties,such as permeabilityand porosity.1.2 Hydraulic fracturing
4、 is the widely accepted field methodavailable for in situ stress measurements at depths greater than50 m.It can be used in drill holes of any diameter.1.3 Hydraulic fracturing can also be used in short holes forwhich other stress measuring methods,such as overcoring,arealso available.The advantage o
5、f hydraulic fracturing is that ityields stresses averaged over a few square metres(the size ofthe induced hydraulic fracture)rather than over grain sizeareas,as in the case of overcoring techniques.1.4 All observed and calculated values shall conform to theguidelines for significant digits and round
6、ing established inPractice D6026.1.4.1 The method used to specifiy how data are collected,calculated,or recorded in this standard is not directly related tothe accuracy to which the data can be applied in design or otheruses,or both.How one applies the results obtained using thisstandard is beyond i
7、ts scope.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety problems,if any,associated with its use.It is theresponsibility of the user of this standard to establish
8、 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD2113 Practice for Rock Core Drilling and Sampling ofRock for Site ExplorationD3740 Pr
9、actice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD5079 Practices for Preserving and Transporting Rock CoreSamplesD6026 Practice for Using Significant Digits in GeotechnicalData3.Terminology3.1 For terminolo
10、gy used in this test method,refer toTerminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 breakdown pressurethe pressure required to inducea hydraulic fracture in a previously intact test interval.3.2.2 in-situ stressrock stress measured in situ(as op-posed to by remote sensing).
11、3.2.3 secondary breakdown(or fracture reopening,or re-frac)pressure the pressure required to reopen a closed,previously induced hydrofracture after the test interval pressurehas been allowed to return to its initial condition.3.2.4 shut-in pressure(or ISIP(instantaneous shut-inpressure)the pressure
12、reached when the induced hydrofrac-ture closes back after pumping is stopped.3.2.5 vertical and horizontal principal stresses the threeprincipal stresses in situ are generally assumed to act one in thevertical direction and the other two in the horizontal plane.4.Summary of Test Method4.1 Asection o
13、f the borehole is isolated by pressurizing twoinflatable rubber packers.The fluid pressure in the sealed-off1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1,2008.
14、Published July 2008.Originally approvedin 1987.Last previous edition approved in 2004 as D4645 041.DOI:10.1520/D4645-08.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to t
15、he standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 interval between the two packers is raised by pumping fluidinto it at a
16、 controlled rate until a fracture occurs in the boreholewall.Pumping is stopped and the pressure in the interval isallowed to stabilize.The pressure is then reduced to the porepressure level of the rock formation,and the pressurizationprocess is repeated several times maintaining the same flowrate.Additional pressure cycles can be conducted at differentflow rates.The magnitudes of the principal stresses arecalculated from the various pressure readings.The orientationof the fracture is detected i