ASTM_D_6274_-_18.pdf

Designation:D627418Standard 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 and Fig.2).1.2.1 Gamma logs are commonly used to delineatelithology,correlate measurements made on different loggingruns,and define stratigraphic correlation between boreholes(See Fig.3).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 This guide is to be used in conjunction with GuideD5753.1.6Gamma logs should be collected by an operator that istrained in geophysical logging procedures.Gamma logs shouldbe interpreted by a professional experienced in log analysis.1.7 The values stated in either SI units or inch-pound unitsgiven in brackets are to be regarded separately as standard.The values 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 noncon-formance with the standard.Reporting of test results in unitsother than SI shall not be regarded as nonconformance withthis standard.1.7.1 The gamma log is typically recorded in units of countsper second(cps)or American Petroleum Institute(API)units.The gamma ray API unit is defined as1200of the differencebetween the count rate recorded by a logging tool in the middleof the radioactive bed and that recorded in the middle of thenonradioactive bed”recorded within the calibration pit.Acalibration facility for API units currently exists at the Univer-sity of Houston and is the world standard for the simpleGamma Ray tool,however the validity of the calibration pithas been called into question in recent years.1.8 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.1.9 This guide offers an organized collection of informationor 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.1.10 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.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 Dec.15,2018.Published January 2019.Originallyapproved in 1998.Last previous edition approved in 2010 as D627410.DOI:10.1520/D6274-18.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the Worl