ASTM_D_6274_-_10.pdf

Designation:D627410Standard Guide forConducting Borehole Geophysical Logging-Gamma1This standard is issued under the fixed designation D6274;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 guide covers the general procedures necessary toconduct gamma,natural gamma,total count gamma,or gammaray(hereafter referred to as gamma)logging of boreholes,wells,access tubes,caissons,or shafts(hereafter referred to asboreholes)as commonly applied to geologic,engineering,groundwater,and environmental(hereafter referred to as geo-technical)investigations.Spectral gamma and logging wheregamma measurements are made in conjunction with a nuclearsource are excluded(for example,neutron activation andgamma-gamma density logs).Gamma logging for minerals orpetroleum applications are excluded.1.2 This guide defines a gamma log as a record of gammaactivity of the formation adjacent to a borehole with depth(SeeFig.1).1.2.1 Gamma logs are commonly used to delineatelithology,correlate measurements made on different loggingruns,and define stratigraphic correlation between boreholes(See Fig.2).1.3 This guide is restricted to gamma logging with nuclearcounters consisting of scintillation detectors(crystals coupledwith photomultiplier tubes),which are the most commongamma measurement devices used in geotechnical applica-tions.1.4 This guide provides an overview of gamma loggingincluding general procedures,specific documentation,calibra-tion and standardization,and log quality and interpretation.1.5 To obtain additional information on gamma logs,seeSection 13.1.6 This guide is to be used in conjunction with GuideD5753.1.7Gamma logs should be collected by an operator that istrained in geophysical logging procedures.Gamma logs shouldbe interpreted by a professional experienced in log analysis.1.8 The geotechnical industry uses English or SI units.Thegamma log is typically recorded in units of counts per second(cps)or American Petroleum Institute(API)units.1.9 This guide does not purport to address all of the safetyand liability problems(for example,lost or lodged probes andequipment decontamination)associated with its use.1.10 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.1.11 This guide offers an organized collection of informa-tion or a series of options and does not recommend a specificcourse of action.This document cannot replace education orexperience and should be used in conjunction with professionaljudgment.Not all aspects of this guide may be applicable in allcircumstances.This ASTM standard is not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must be judged,nor should thisdocument be applied without consideration of a projects manyunique aspects.The word“Standard”in the title of thisdocument means only that the document has been approvedthrough the ASTM consensus process.2.Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD5088 Practice for Decontamination of Field EquipmentUsed at Waste SitesD5608 Practices for Decontamination of Field EquipmentUsed at Low Level Radioactive Waste SitesD5753 Guide for Planning and Conducting Borehole Geo-physical LoggingD6167 Guide for Conducting Borehole Geophysical Log-ging:Mechanical Caliper3.Terminology3.1 Definitions:1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.01 on Surface and SubsurfaceCharacterization.Current edition approved Oct.1,2010.Published March 2011.Originallyapproved in 1998.Last previous edition approved in 2004 as D627498(2004).DOI:10.1520/D6274-10.2For 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 the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.1 Definitions shall be in accordance with TerminologyD653,Ref(1),or as defined below.3.2 Definitions of Terms Specific to This Standard:3.2.1 accuracy,nhow close measured log values approachtrue value.It is determined in a controlled environment.Acontrolled environment represents a homogeneous samplevolume with known properties.3.2.2 dead time,nthe time after each pulse when a secondpulse cannot be detected.3.2.3 dead time effect,nthe inability to distinguishclosely-spaced nuclear counts leads to a significant underesti