ASTM D6274-18
(Guide)Standard Guide for Conducting Borehole Geophysical Logging - Gamma
Standard Guide for Conducting Borehole Geophysical Logging - Gamma
SIGNIFICANCE AND USE
5.1 An appropriately developed, documented, and executed guide is essential for the proper collection and application of gamma logs. This guide is to be used in conjunction with Guide D5753.
5.2 The benefits of its use include improving selection of gamma logging methods and equipment, gamma log quality and reliability, and usefulness of the gamma log data for subsequent display and interpretation.
5.3 This guide applies to commonly used gamma logging methods for geotechnical applications.
5.4 It is essential that personnel (see the Personnel section of Guide D5753) consult up-to-date textbooks and reports on the gamma technique, application, and interpretation methods.
SCOPE
1.1 This guide covers the general procedures necessary to conduct gamma, natural gamma, total count gamma, or gamma ray (hereafter referred to as gamma) logging of boreholes, wells, access tubes, caissons, or shafts (hereafter referred to as boreholes) as commonly applied to geologic, engineering, groundwater, and environmental (hereafter referred to as geotechnical) investigations. Spectral gamma and logging where gamma measurements are made in conjunction with a nuclear source are excluded (for example, neutron activation and gamma-gamma density logs). Gamma logging for minerals or petroleum applications are excluded.
1.2 This guide defines a gamma log as a record of gamma activity of the formation adjacent to a borehole with depth (See Fig. 1 and Fig. 2).
FIG. 1 Example of a Gamma Log From Near the South Rim of the Grand Canyon in the USA (in cps)
Note 1: This figure demonstrates how the log can be used to identify specific formations, illustrating scale wrap-around for a local gamma peak, and showing how the contact between two formations is picked to coincide with the half-way point of the transition between the gamma activities of the two formations.
FIG. 2 Example of a Gamma Log for the Hydrologic Observation Well KGS #1 Braun located near Hays, Kansas in the USA (in API units whereby SGR reflects the derived total gamma ray log (the sum of all the radiation contributions), and CGR reflects the computed gamma ray log (the sum of the potassium and thorium responses, leaving out the contribution from uranium).
1.2.1 Gamma logs are commonly used to delineate lithology, correlate measurements made on different logging runs, and define stratigraphic correlation between boreholes (See Fig. 3).
FIG. 3 Example of Gamma Logs From Two Boreholes
Note 1: From a study site showing how the gamma logs can be used to identify where beds intersect each of the individual boreholes, demonstrating lateral continuity of the subsurface geology.
1.3 This guide is restricted to gamma logging with nuclear counters consisting of scintillation detectors (crystals coupled with photomultiplier tubes), which are the most common gamma measurement devices used in geotechnical applications.
1.4 This guide provides an overview of gamma logging including general procedures, specific documentation, calibration and standardization, and log quality and interpretation.
1.5 This guide is to be used in conjunction with Guide D5753.
1.6 Gamma logs should be collected by an operator that is trained in geophysical logging procedures. Gamma logs should be interpreted by a professional experienced in log analysis.
1.7 The values stated in either SI units or inch-pound units [given 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 nonconformance with the standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard.
1.7.1 The gamma log is typically recorded in units of counts per second (cps) or American Petroleum Institute (API) units. The gamma ray API unit is defined as 1/20...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6274 − 18
Standard Guide for
1
Conducting Borehole Geophysical Logging - Gamma
This standard is issued under the fixed designation D6274; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 The values stated in either SI units or inch-pound units
[given in brackets] are to be regarded separately as standard.
1.1 This guide covers the general procedures necessary to
The values stated in each system may not be exact equivalents;
conductgamma,naturalgamma,totalcountgamma,orgamma
therefore,eachsystemshallbeusedindependentlyoftheother.
ray (hereafter referred to as gamma) logging of boreholes,
Combining values from the two systems may result in noncon-
wells, access tubes, caissons, or shafts (hereafter referred to as
formance with the standard. Reporting of test results in units
boreholes) as commonly applied to geologic, engineering,
other than SI shall not be regarded as nonconformance with
groundwater, and environmental (hereafter referred to as geo-
this standard.
technical) investigations. Spectral gamma and logging where
1.7.1 Thegammalogistypicallyrecordedinunitsofcounts
gamma measurements are made in conjunction with a nuclear
per second (cps) or American Petroleum Institute (API) units.
source are excluded (for example, neutron activation and
1
The gamma ray API unit is defined as ⁄200 of the difference
gamma-gamma density logs). Gamma logging for minerals or
betweenthecountraterecordedbyaloggingtoolinthemiddle
petroleum applications are excluded.
of the radioactive bed and that recorded in the middle of the
1.2 This guide defines a gamma log as a record of gamma
nonradioactive bed” recorded within the calibration pit. A
activityoftheformationadjacenttoaboreholewithdepth(See
calibration facility forAPI units currently exists at the Univer-
Fig. 1 and Fig. 2).
sity of Houston and is the world standard for the simple
1.2.1 Gamma logs are commonly used to delineate
Gamma Ray tool, however the validity of the calibration pit
lithology, correlate measurements made on different logging
has been called into question in recent years.
runs, and define stratigraphic correlation between boreholes
1.8 This standard does not purport to address all of the
(See Fig. 3).
safety concerns, if any, associated with its use. It is the
1.3 This guide is restricted to gamma logging with nuclear
responsibility of the user of this standard to establish appro-
counters consisting of scintillation detectors (crystals coupled
priate safety, health, and environmental practices and deter-
with photomultiplier tubes), which are the most common
mine the applicability of regulatory limitations prior to use.
gamma measurement devices used in geotechnical applica-
1.9 This guide offers an organized collection of information
tions.
or a series of options and does not recommend a specific
course of action. This document cannot replace education or
1.4 This guide provides an overview of gamma logging
experienceandshouldbeusedinconjunctionwithprofessional
including general procedures, specific documentation, calibra-
judgment. Not all aspects of this guide may be applicable in all
tion and standardization, and log quality and interpretation.
circumstances. This ASTM standard is not intended to repre-
1.5 This guide is to be used in conjunction with Guide
sent or replace the standard of care by which the adequacy of
D5753.
a given professional service must be judged, nor should this
1.6 Gamma logs should be collected by an operator that is
document be applied without consideration of a project’s many
trained in geophysical logging procedures. Gamma logs should
unique aspects. The word “Standard” in the title of this
be interpreted by a professional experienced in log analysis.
document means only that the document has been approved
through the ASTM consensus process.
1.10 This international standard was developed in accor-
1
dance with internationally recognized principles on standard-
This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rock
and is the direct responsibility of Subcommittee D18.01 on Surface and Subsurface
ization established in the Decision on Principles for the
Characterization.
Development of International Standards, Guides and Recom-
Current edition approved Dec. 15, 2018. Published January 2019. Originally
mendations issued by the World Trade Organization Technical
approved in 1998. Last previous edition approved in 2010 a
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6274 − 10 D6274 − 18
Standard Guide for
1
Conducting Borehole Geophysical Logging - Gamma
This standard is issued under the fixed designation D6274; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide covers the general procedures necessary to conduct gamma, natural gamma, total count gamma, or gamma ray
(hereafter referred to as gamma) logging of boreholes, wells, access tubes, caissons, or shafts (hereafter referred to as boreholes)
as commonly applied to geologic, engineering, groundwater, and environmental (hereafter referred to as geotechnical)
investigations. Spectral gamma and logging where gamma measurements are made in conjunction with a nuclear source are
excluded (for example, neutron activation and gamma-gamma density logs). Gamma logging for minerals or petroleum
applications are excluded.
1.2 This guide defines a gamma log as a record of gamma activity of the formation adjacent to a borehole with depth (See Fig.
1 and Fig. 2).
1.2.1 Gamma logs are commonly used to delineate lithology, correlate measurements made on different logging runs, and define
stratigraphic correlation between boreholes (See Fig. 23).
1.3 This guide is restricted to gamma logging with nuclear counters consisting of scintillation detectors (crystals coupled with
photomultiplier tubes), which are the most common gamma measurement devices used in geotechnical applications.
1.4 This guide provides an overview of gamma logging including general procedures, specific documentation, calibration and
standardization, and log quality and interpretation.
1.5 To obtain additional information on gamma logs, see Section 13.
1.5 This guide is to be used in conjunction with Guide D5753.
1.6 Gamma logs should be collected by an operator that is trained in geophysical logging procedures. Gamma logs should be
interpreted by a professional experienced in log analysis.
1.7 The geotechnical industry uses English or SI units. The gamma log is typically recorded in units of counts per second (cps)
or American Petroleum Institute (API) units.values stated in either SI units or inch-pound units [given 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 nonconformance with the standard.
Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard.
1.7.1 The gamma log is typically recorded in units of counts per second (cps) or American Petroleum Institute (API) units. The
1
gamma ray API unit is defined as ⁄200 of the difference between the count rate recorded by a logging tool in the middle of the
radioactive bed and that recorded in the middle of the nonradioactive bed” recorded within the calibration pit. A calibration facility
for API units currently exists at the University of Houston and is the world standard for the simple Gamma Ray tool, however the
validity of the calibration pit has been called into question in recent years.
1.9 This guide does not purport to address all of the safety and liability problems (for example, lost or lodged probes and
equipment decontamination) associated with its use.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.9 This guide offers an organized collection of information or a series of options and does not recommend a specific course
of action. This document cannot replace education or experience and should be used in conjunction with professional judgment.
Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace
1
This guide is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.01 on Surface and Subsurface
Characterization.
Current edition approved Oct. 1, 2010Dec. 15, 2018. Published March 2011January 2019. Originally approved in 1998. Last previous edition approved in 2
...
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