ASTM_D_7400_-_D_7400M_-_19.pdf

Designation:D7400/D7400M19Standard Test Methods forDownhole Seismic Testing1This standard is issued under the fixed designation D7400/D7400M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 These test methods address compression(P)and shear(S)waves propagating in the downward direction in a nearlyvertical plane.The seismic waves can be denoted as PVor PZfor a downward propagating compression wave and as SVHorSZXfor downward propagating and horizontally polarizedshear wave.The SVHor SZXis also referred to as an SHwave.These test methods are limited to the determination of theinterval velocities from arrival times and relative arrival timesof compression(P)waves and vertically(SV)and horizontally(SH)oriented shear(S)seismic waves which are generatednear surface and travel down to an array of vertically installedseismic sensors.Two methods are discussed,which includeusing either one or two downhole sensors(receivers).1.2 Various applications of the data will be addressed andacceptable procedures and equipment,such as seismic sources,receivers,and recording systems will be discussed.Other itemsaddressed include source-to-receiver spacing,drilling,casing,grouting,a procedure for borehole installation,and conductingactual borehole and seismic cone tests.Data reduction andinterpretation is limited to the identification of various seismicwave types,apparent velocity relation to true velocity,examplecomputations,use of Snells law of refraction,and assump-tions.1.3 There are several acceptable devices that can be used togenerate a high-quality P or SV source wave or both and SHsource waves.Several types of commercially available receiv-ers and recording systems can also be used to conduct anacceptable downhole survey.Special consideration should begiven to the types of receivers used and their configuration toprovide an output that accurately reflects the input motion.These test methods primarily concern the actual test procedure,data interpretation,and specifications for equipment which willyield uniform test results.1.4 All recorded and calculated values shall conform to theguide for significant digits and rounding established in PracticeD6026.1.4.1 The procedures used to specify how data are collected/recorded and calculated in these test methods are regarded asthe industry standard.In addition,they are representative of thesignificant digits that should generally be retained.The proce-dures used do not consider material variation,purpose forobtaining the data,special purpose studies,or any consider-ations for the users objectives;and it is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations.It is beyond the scopeof these test methods to consider significant digits used inanalysis methods for engineering design.1.4.2 Measurements made to more significant digits orbetter sensitivity than specified in these test methods shall notbe regarded a nonconformance with this standard.1.5 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard.Thevalues stated in each system may not be exact equivalents;therefore,each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the standard.1.5.1 The gravitational system of inch-pound units is usedwhen dealing with inch-pound units.In this system,the pound(lbf)represents a unit of force(weight),while the unit for massis slugs.The rationalized slug unit is not given,unless dynamic(F=ma)calculations are involved.1.5.2 It is common practice in the engineering/constructionprofession to concurrently use pounds to represent both a unitof mass(lbm)and of force(lbf).This implicitly combines twoseparate systems of units;that is,the absolute system and thegravitational system.It is scientifically undesirable to combinethe use of two separate sets of inch-pound units within a singlestandard.As stated,this standard includes the gravitationalsystem of inch-pound units and does not use/present the slugunit for mass.However,the use of balances or scales recordingpounds of mass(lbm)or recording density in lbm/ft3shall notbe regarded as nonconformance with this standard.1.6 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.09 on Cyclic andDynamic Properties of Soils.Current edition approved Feb.1,2019.