ASTM D7400-17
(Test Method)Standard Test Methods for Downhole Seismic Testing
Standard Test Methods for Downhole Seismic Testing
SIGNIFICANCE AND USE
5.1 The seismic downhole method provides a designer with information pertinent to the seismic wave velocities of the materials in question (1)3. The P-wave and S-wave velocities are directly related to the important geotechnical elastic constants of Poisson’s ratio, shear modulus, bulk modulus, and Young’s modulus. Accurate in-situ P-wave and S-wave velocity profiles are essential in geotechnical foundation designs. These parameters are used in both analyses of soil behavior under both static and dynamic loads where the elastic constants are input variables into the models defining the different states of deformations such as elastic, elasto-plastic, and failure. Another important use of estimated shear wave velocities in geotechnical design is in the liquefaction assessment of soils.
5.2 A fundamental assumption inherent in the test methods is that a laterally homogeneous medium is being characterized. In a laterally homogeneous medium the source wave train trajectories adhere to Snell’s law of refraction. Another assumption inherent in the test methods is that the stratigraphic medium to be characterized can have transverse isotropy. Transverse isotropy is a particularly simple form of anisotropy because velocities only vary with vertical incidence angle and not with azimuth. By placing and actuating the seismic source at offsets rotated 90° in plan view, it may be possible to evaluate the transverse anisotropy of the medium.
5.3 In soft saturated soil, where the P-wave velocity of the soil is less than the P-wave velocity of water, which is about 1450 m/s [4750 ft/s], the P-wave velocity measurement will be controlled by the P-wave velocity of water and a direct measurement of the soil P-wave velocity will not be possible.
Note 1: The quality of the results produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities. Agencies that meet the criteria of Practice D3740 are gener...
SCOPE
1.1 These test methods are limited to the determination of the interval velocities from arrival times and relative arrival times of compression (P) waves and vertically (SV) and horizontally (SH) oriented shear (S) seismic waves which are generated near surface and travel down to an array of vertically installed seismic sensors. Two methods are discussed, which include using either one or two downhole sensors (receivers).
1.2 Various applications of the data will be addressed and acceptable procedures and equipment, such as seismic sources, receivers, and recording systems will be discussed. Other items addressed include source-to-receiver spacing, drilling, casing, grouting, a procedure for borehole installation, and conducting actual borehole and seismic cone tests. Data reduction and interpretation is limited to the identification of various seismic wave types, apparent velocity relation to true velocity, example computations, use of Snell's law of refraction, and assumptions.
1.3 There are several acceptable devices that can be used to generate a high-quality P or SV source wave or both and SH source waves. Several types of commercially available receivers and recording systems can also be used to conduct an acceptable downhole survey. Special consideration should be given to the types of receivers used and their configuration to provide an output that accurately reflects the input motion. These test methods primarily concern the actual test procedure, data interpretation, and specifications for equipment which will yield uniform test results.
1.4 All recorded and calculated values shall conform to the guide for significant digits and rounding established in Practice D6026.
1.4.1 The procedures used to specify how data are collected/recorded and calculated in these test methods are regarded as the industry standard. In addition, they are representative of the significant digits that should generally be re...
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Designation: D7400 − 17
Standard Test Methods for
1
Downhole Seismic Testing
This standard is issued under the fixed designation D7400; 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* obtaining the data, special purpose studies, or any consider-
ations for the user’s objectives; and it is common practice to
1.1 These test methods are limited to the determination of
increase or reduce significant digits of reported data to be
the interval velocities from arrival times and relative arrival
commensuratewiththeseconsiderations.Itisbeyondthescope
times of compression (P) waves and vertically (SV) and
of these test methods to consider significant digits used in
horizontally (SH) oriented shear (S) seismic waves which are
analysis methods for engineering design.
generatednearsurfaceandtraveldowntoanarrayofvertically
installed seismic sensors. Two methods are discussed, which
1.4.2 Measurements made to more significant digits or
include using either one or two downhole sensors (receivers).
better sensitivity than specified in these test methods shall not
be regarded a nonconformance with this standard.
1.2 Various applications of the data will be addressed and
acceptable procedures and equipment, such as seismic sources,
1.5 The values stated in either SI units or inch-pound units
receivers,andrecordingsystemswillbediscussed.Otheritems
(given in brackets) are to be regarded separately as standard.
addressed include source-to-receiver spacing, drilling, casing,
The values stated in each system may not be exact equivalents;
grouting, a procedure for borehole installation, and conducting
therefore,eachsystemshallbeusedindependentlyoftheother.
actual borehole and seismic cone tests. Data reduction and
Combining values from the two systems may result in non-
interpretation is limited to the identification of various seismic
conformance with the standard. Reporting of test results in
wavetypes,apparentvelocityrelationtotruevelocity,example
units other than SI shall not be regarded as non-conformance
computations, use of Snell’s law of refraction, and assump-
with this standard.
tions.
1.5.1 The gravitational system of inch-pound units is used
1.3 There are several acceptable devices that can be used to
when dealing with inch-pound units. In this system, the pound
generate a high-quality P or SV source wave or both and SH
(lbf) represents a unit of force (weight), while the unit for mass
source waves. Several types of commercially available receiv-
is slugs.The rationalized slug unit is not given, unless dynamic
ers and recording systems can also be used to conduct an
(F = ma) calculations are involved.
acceptable downhole survey. Special consideration should be
1.5.2 It is common practice in the engineering/construction
given to the types of receivers used and their configuration to
provide an output that accurately reflects the input motion. profession to concurrently use pounds to represent both a unit
Thesetestmethodsprimarilyconcerntheactualtestprocedure, of mass (lbm) and of force (lbf). This implicitly combines two
datainterpretation,andspecificationsforequipmentwhichwill
separate systems of units; that is, the absolute system and the
yield uniform test results.
gravitational system. It is scientifically undesirable to combine
the use of two separate sets of inch-pound units within a single
1.4 All recorded and calculated values shall conform to the
standard. As stated, this standard includes the gravitational
guide for significant digits and rounding established in Practice
system of inch-pound units and does not use/present the slug
D6026.
unit for mass. However, the use of balances or scales recording
1.4.1 Theproceduresusedtospecifyhowdataarecollected/
3
recorded and calculated in these test methods are regarded as pounds of mass (lbm) or recording density in lbm/ft shall not
theindustrystandard.Inaddition,theyarerepresentativeofthe be regarded as nonconformance with this standard.
significant digits that should generally be retained. The proce-
1.6 This standard does not purport to address all of the
dures used do not consider material variation, purpose for
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
mine the applicability of regulatory limitations prior to use.
Rock and is the direct responsibility of Subcommittee D18.09 on Cyclic and
Dynamic Properties of Soils.
1.7 This international standard w
...
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: D7400 − 14 D7400 − 17
Standard Test Methods for
1
Downhole Seismic Testing
This standard is issued under the fixed designation D7400; 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 These test methods are limited to the determination of the interval velocities from arrival times and relative arrival times
of compression (P) waves and vertically (SV) and horizontally (SH) polarizedoriented shear (S) seismic waves which are generated
near surface and travel down to an array of vertically installed seismic sensors. A preferred method intended to obtain data for use
on critical projects where the highest quality data is required is included. Also included is an optional method intended for use on
projects which do not require measurements of a high degree of precision. Two methods are discussed, which include using either
one or two downhole sensors (receivers).
1.2 Various applications of the data will be addressed and acceptable procedures and equipment, such as seismic sources,
receivers, and recording systems will be discussed. Other items addressed include source-to-receiver spacing, drilling, casing,
grouting, a procedure for borehole installation, and conducting actual borehole and seismic cone tests. Data reduction and
interpretation is limited to the identification of various seismic wave types, apparent velocity relation to true velocity, example
computations, use of Snell’s law of refraction, and assumptions.
1.3 There are several acceptable devices that can be used to generate a high-quality P or SV source wave or both and SH source
waves. Several types of commercially available receivers and recording systems can also be used to conduct an acceptable
downhole survey. Special consideration should be given to the types of receivers used and their configuration. Heavily-damped
sensors should not be used so that spectral smearing, phase shifting, and latency response between sensors is avoided. configuration
to provide an output that accurately reflects the input motion. These test methods primarily concern the actual test procedure, data
interpretation, and specifications for equipment which will yield uniform test results.
1.4 All recorded and calculated values shall conform to the guide for significant digits and rounding established in Practice
D6026.
1.4.1 The procedures used to specify how data are collected/recorded and calculated in these test methods are regarded as the
industry standard. In addition, they are representative of the significant digits that should generally be retained. The procedures
used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s
objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these
considerations. It is beyond the scope of these test methods to consider significant digits used in analysis methods for engineering
design.
1.4.2 Measurements made to more significant digits or better sensitivity than specified in these test methods shall not be
regarded a nonconformance with this standard.
1.5 This standard is written using SI units. Inch-pound units are provided for convenience. 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 inch pound units each system
may not be exact equivalents; therefore, they each system shall be used independently of the SI system. other. Combining values
from the two systems may result in nonconformance with non-conformance with the standard. Reporting of test results in units
other than SI shall not be regarded as non-conformance with this standard.
1.5.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf)
represents a unit of force (weight), while the unit for mass is 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/construction profession to concurrently use pounds to represent both a unit of
mass (lbm) and of force (lbf). This implicitly combines two separate systems of units; that is, the absolute system and the
1
This test method is under
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