ASTM D4631-18

Standard Test Method for Determining Transmissivity and Storativity of Low Permeability Rocks by In Situ Measurements Using Pressure Pulse Technique

SIGNIFICANCE AND USE
5.1 Test Method—The pulse test method is used to determine the transmissivity and storativity of low-permeability formations surrounding the packed-off intervals. This test method is considerably shorter in duration than the pumping and slug tests used in more permeable rocks. To obtain results to the desired accuracy, pumping and slug tests in low-permeability formations are too time consuming, as indicated in Fig. 1 (from Bredehoeft and Papadopulos (1)).4  
5.2 transmissivity, T—the transmissivity of a formation of thickness, b, is defined as follows:
   where:  
  K  =  equivalent formation hydraulic conductivity (efhc).  
The efhc is the hydraulic conductivity of a material if it were homogeneous and porous over the entire interval. The hydraulic conductivity, K, is related to the equivalent formation, k, as follows:
     where:  
  ρ  =  fluid density,   μ  =  fluid viscosity, and   g  =  acceleration due to gravity.    
5.3 storativity, S—the storativity (or storage coefficient) of a formation of thickness, b, is defined as follows:
   where:  
  Ss  =  equivalent bulk rock specific storage (ebrss).  
The ebrss is defined as the specific storage of a material if it were homogeneous and porous over the entire interval. The specific storage is given as follows:
    where:  
  Cb  =  bulk rock compressibility,   Cw  =  fluid compressibility, and   n  =  formation porosity.    
5.4 Analysis—The transient pressure data obtained using the suggested method are evaluated by the curve-matching technique described by Bredehoeft and Papadopulos (1), or by an analytical technique proposed by Wang et al (2). The latter is particularly useful for interpreting pulse tests when only the early-time transient pressure decay data are available.  
5.5 Units:  
5.5.1 Conversions—The permeability of a formation is often expressed in terms of the unit darcy. A porous medium has a permeability of 1 darcy when a fluid of viscosity ...
SCOPE
1.1 This test method covers a field procedure for determining the transmissivity and storativity of geological formations having permeabilities lower than 10−3 μm2 (1 millidarcy) using the pressure pulse technique.  
1.2 The transmissivity and storativity values determined by this test method provide a good approximation of the capacity of the zone of interest to transmit water, if the test intervals are representative of the entire zone and the surrounding rock is fully water saturated.  
1.3 Units—The values stated in SI units are to be regarded as the standard. The values in parentheses are mathematical conversions provided for information only and are not considered standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard.  
1.4 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026, unless superseded by this standard.  
1.4.1 For purposes of comparing a measured or calculated value(s) with specified limits, the measured or calculated value(s) shall be rounded to the nearest decimal or significant digits in the specified limits.  
1.4.2 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should 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 conditions. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It i...

General Information

• Status: Published
• Publication Date: 14-Jul-2018
• ICS: 07.040 - Astronomy. Geodesy. Geography
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.21 - Groundwater and Vadose Zone Investigations

Relations

• Replaces: ASTM D4631-95(2008) - Standard Test Method for Determining Transmissivity and Storativity of Low Permeability Rocks by In Situ Measurements Using Pressure Pulse Technique (Withdrawn 2017)
• Effective Date: 15-Jul-2018
• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014
• Refers: ASTM D3740-12a - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-May-2012
• Refers: ASTM D3740-12 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2012
• Refers: ASTM D653-11 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Sep-2011
• Refers: ASTM D3740-11 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Sep-2011
• Refers: ASTM F2070-00(2011) - Standard Specification for Transducers, Pressure and Differential, Pressure, Electrical and Fiber-Optic
• Effective Date: 01-Apr-2011
• Refers: ASTM D3740-10 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2010
• Refers: ASTM D653-09 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Jan-2009
• Refers: ASTM D653-08a - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Dec-2008
• Refers: ASTM D653-08 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Nov-2008
• Refers: ASTM D2113-08 - Standard Practice for Rock Core Drilling and Sampling of Rock for Site Investigation
• Effective Date: 01-Oct-2008
• Refers: ASTM D3740-08 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2008

Overview

ASTM D4631-18 is the internationally recognized standard test method for determining the transmissivity and storativity of low permeability rocks using in situ pressure pulse testing. Developed by ASTM International, this method offers a reliable procedure to assess the hydraulic properties of geological formations with very low permeability, specifically those less than 1 millidarcy (10⁻³ μm²). Unlike traditional pumping or slug tests, the pressure pulse technique is significantly shorter in duration, making it ideal for field investigations where time efficiency and representative data are critical.

This standard is primarily utilized in hydrogeology and geotechnical engineering to estimate a formation's ability to transmit and store groundwater. Values obtained help characterize the groundwater flow properties of the tested formation, supporting resource planning, environmental assessments, and engineering design.

Key Topics

• Transmissivity Measurement: Describes a formation’s capacity to transmit water and is essential for understanding subsurface flow.
• Storativity Calculation: Determines how much water a formation can store, providing insight into groundwater availability and aquifer performance.
• Pressure Pulse Test Technique: Involves the application of a rapid pressure pulse to a water-filled zone of interest within a borehole, with the subsequent pressure response recorded and analyzed.
• Applicability: Specifically designed for low permeability rocks where pumping or slug tests are inefficient.
• Test Equipment: Discusses packers, pumps, pressure transducers, and requirements for clean, compatible test water.
• Data Analysis: Outlines evaluation methods, such as curve-matching and analytical interpretation, for pressure decay data.
• Reporting: Specifies the minimum necessary data to document, including test interval descriptions, apparatus details, procedures, and results performance.

Applications

ASTM D4631-18 has practical value in a range of field applications, especially where precise knowledge of hydraulic properties in low-permeability formations is critical. Typical use cases include:

• Hydrogeological Site Characterization: Supporting groundwater resource evaluation and contamination studies.
• Geotechnical Engineering Design: Informing foundation engineering, tunneling, dam construction, and underground waste disposal projects.
• Environmental Impact Assessments: Assessing potential migration pathways for contaminants through low permeability zones.
• Fractured Rock and Karst Terrain Analysis: Identifying properties of discontinuities such as fault zones, bedding planes, and joint systems.
• Regulatory Compliance: Meeting requirements for groundwater modeling and site assessment set by environmental and water resource authorities.

Related Standards

For comprehensive site investigations and data integrity, ASTM D4631-18 references and complements several other ASTM standards:

• ASTM D653: Terminology Relating to Soil, Rock, and Contained Fluids
• ASTM D2113: Practice for Rock Core Drilling and Sampling for Site Exploration
• ASTM D3740: Minimum Requirements for Agencies Engaged in Testing/Inspection of Soil and Rock
• ASTM D6026: Practice for Using Significant Digits in Geotechnical Data for consistency in reported results
• ASTM F2070: Specification for Pressure Transducers used during the test procedure

These related documents help ensure the quality, consistency, and reliability of pressure pulse test results in low-permeability rock and support a standardized approach to groundwater and geotechnical studies.

Keywords: ASTM D4631-18, transmissivity, storativity, pressure pulse test, low permeability rock, hydrogeology, groundwater testing, field method, in situ testing, geotechnical engineering, environmental site assessment, groundwater flow, permeability testing, aquifer characterization

Standards Content (Sample)

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: D4631 − 18
Standard Test Method for
Determining Transmissivity and Storativity of Low
Permeability Rocks by In Situ Measurements Using
Pressure Pulse Technique
This standard is issued under the fixed designation D4631; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers a field procedure for determin-
responsibility of the user of this standard to establish appro-
ing the transmissivity and storativity of geological formations
−3 2 priate safety, health, and environmental practices and deter-
havingpermeabilitieslowerthan10 µm (1millidarcy)using
mine the applicability of regulatory limitations prior to use.
the pressure pulse technique.
1.6 This international standard was developed in accor-
1.2 The transmissivity and storativity values determined by
dance with internationally recognized principles on standard-
this test method provide a good approximation of the capacity
ization established in the Decision on Principles for the
of the zone of interest to transmit water, if the test intervals are
Development of International Standards, Guides and Recom-
representative of the entire zone and the surrounding rock is
mendations issued by the World Trade Organization Technical
fully water saturated.
Barriers to Trade (TBT) Committee.
1.3 Units—The values stated in SI units are to be regarded
2. Referenced Documents
as the standard. The values in parentheses are mathematical
conversions provided for information only and are not consid-
2.1 ASTM Standards:
ered standard. Reporting of test results in units other than SI
D653Terminology Relating to Soil, Rock, and Contained
shall not be regarded as nonconformance with this standard.
Fluids
D2113Practice for Rock Core Drilling and Sampling of
1.4 All observed and calculated values shall conform to the
Rock for Site Exploration
guidelines for significant digits and rounding established in
D3740Practice for Minimum Requirements for Agencies
Practice D6026, unless superseded by this standard.
Engaged in Testing and/or Inspection of Soil and Rock as
1.4.1 For purposes of comparing a measured or calculated
Used in Engineering Design and Construction
value(s) with specified limits, the measured or calculated
D5717Guide for Design of Ground-Water Monitoring Sys-
value(s) shall be rounded to the nearest decimal or significant
tems in Karst and Fractured-Rock Aquifers (Withdrawn
digits in the specified limits.
2005)
1.4.2 Theproceduresusedtospecifyhowdataarecollected/
D6026Practice for Using Significant Digits in Geotechnical
recorded or calculated in this standard are regarded as the
Data
industry standard. In addition, they are representative of the
F2070 Specification for Transducers, Pressure and
significant digits that generally should be retained. The proce-
Differential, Pressure, Electrical and Fiber-Optic
dures used do not consider material variation, purpose for
obtaining the data, special purpose studies, or any consider-
3. Terminology
ations for the user’s objectives; and it is common practice to
increase or reduce significant digits of reported data to be 3.1 Definitions:
commensurate with these conditions. It is beyond the scope of 3.1.1 For definitions of common technical terms in this
this standard to consider significant digits used in analysis standard, refer to Terminology D653.
methods for engineering design.
3.2 Symbols:
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.21 on Groundwater and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Vadose Zone Investigations. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved July 15, 2018. Published August 2018. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 1986. Last previous edition approved in 2008 as D4631–95(2008), the ASTM website.
whichwaswithdrawnJanuary2017andreinstatedJuly2018.DOI:10.1520/D4631- The last approved version of this historical standard is referenced on
18. www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4631 − 18
−1 2
3.2.1 C —bulk rock compressibility [M LT ]. 4.2 The test itself involves applying a pressure pulse to the
b
−1 2
water in the packed-off interval and tubing string, and record-
3.2.2 C —compressibility of water [M LT ].
w
ing the resulting pressure transient. A pressure transducer,
−1
3.2.3 K—hydraulic conductivity [ LT ].
located either in the packed-off zone or in the tubing at the
3.2.3.1 Discussion—The use of the symbol K for the term
surface, measuring the transient as a function of time. The
hydraulic conductivity is the predominant usage in groundwa-
decaycharacteristicsofthepressurepulsearedependentonthe
ter literature by hydrogeolists, whereas the symbol k is com-
transmissivity and storativity of the rock surrounding the
monly used for this term in rock mechanics and soil science.
intervalbeingpulsedandonthevolumeofwaterbeingpulsed.
3.2.4 L—length of packed-off zone [ L].
Alternatively, under non-confining conditions, the pulse test
−1 −2
3.2.5 P—excess test hole pressure [ ML T ].
maybeperformedimposingapressurepulseandthenreleasing
−1 −2
the pressure on a shut-in well, thereby subjecting the well to a
3.2.6 P —initial pressure pulse [ML T ].
o
negative pressure pulse. Interpretation of this test method is
3.2.7 S—storativity (or storage coefficient) (dimensionless).
like that described for the positive pressure pulse.
−1
3.2.8 S —specific storage [ L ].
s
2 −1
3.2.9 T—transmissivity [L T ].
5. Significance and Use
3.2.10 V —volume of water pulsed [L ].
w
5.1 Test Method—The pulse test method is used to deter-
3.2.11 b—formation thickness [L].
mine the transmissivity and storativity of low-permeability
3.2.12 e—fracture aperture [L]. formations surrounding the packed-off intervals. This test
−2 method is considerably shorter in duration than the pumping
3.2.13 g—acceleration due to gravity [ LT ].
and slug tests used in more permeable rocks. To obtain results
3.2.14 k—permeability [L ].
to the desired accuracy, pumping and slug tests in low-
3.2.15 n—porosity (dimensionless).
permeability formations are too time consuming, as indicated
3.2.16 r —radius of test hole [L]. in Fig. 1 (from Bredehoeft and Papadopulos (1)).
w
3.2.17 t—time elapsed from pulse initiation [T].
5.2 transmissivity, T—the transmissivity of a formation of
3.2.18 α—dimensionless parameter. thickness, b, is defined as follows:
3.2.19 β—dimensionless parameter. T 5 K·b (1)
−1 −1
3.2.20 µ—viscosity of water [ML T ].
where:
−3
3.2.21 ρ—density of water [ ML ].
K = equivalent formation hydraulic conductivity (efhc).
Theefhcisthehydraulicconductivityofamaterialifitwere
4. Summary of Test Method
homogeneous and porous over the entire interval. The hydrau-
4.1 Aboreholeisfirstdrilledintotherockmass,intersecting
lic conductivity, K, is related to the equivalent formation, k,as
the geological formations for which the transmissivity and
follows:
storativity are desired. The borehole is cored through potential
K 5 kρg/µ (2)
zonesofinterest,andislatersubjectedtogeophysicalborehole
logging over these intervals. During the test, each interval of
interest is packed off at top and bottom with inflatable rubber
packers attached to high-pressure steel tubing. After inflating 4
The boldface numbers in parentheses refer to a list of references at the end of
the packers, the tubing string is filled with water. this standard.
FIG. 1 Comparative Times for Pressure Pulse and Slug Tests
D4631 − 18
TABLE 1 Viscosity of Water as a Function of Temperature
where:
Temperature, °C Absolute Viscosity, mPa·s
ρ = fluid density,
0 1.79
µ = fluid viscosity, and
2 1.67
g = acceleration due to gravity.
4 1.57
6 1.47
5.3 storativity, S—thestorativity(orstoragecoefficient)ofa
8 1.39
formation of thickness, b, is defined as follows:
10 1.31
12 1.24
S 5 S ·b (3)
s
14 1.17
16 1.11
where:
18 1.06
S = equivalent bulk rock specific storage (ebrss). 20 1.00
s
22 0.96
The ebrss is defined as the specific storage of a material if it
24 0.91
26 0.87
were homogeneous and porous over the entire interval. The
28 0.84
specific storage is given as follows:
30 0.80
32 0.77
S 5 ρg C 1nC (4)
s ~ b w!
34 0.74
36 0.71
where:
38 0.68
C = bulk rock compressibility, 40 0.66
b
C = fluid compressibility, and
w
n = formation porosity.
5.4 Analysis—Thetransientpressuredataobtainedusingthe
suggested method are evaluated by the curve-matching tech- 6. Calibration, Verification, Functional Checks
nique described by Bredehoeft and Papadopulos (1),orbyan
6.1 Prior to use, the test equipment will be verified for
analytical technique proposed by Wang et al (2). The latter is
operation, freedom from leakage and data recording.
particularly useful for interpreting pulse tests when only the
6.2 Pressure transducers will be checked for operation and
early-time transient pressure decay data are available.
verified against known devices or calibrated using known
5.5 Units:
standards (F2070).
5.5.1 Conversions—The permeability of a formation is of-
ten expressed in terms of the unit darcy.Aporous medium has
7. Apparatus
a permeability of 1 darcy when a fluid of viscosity 1 cP (1 NOTE 4—A schematic of the test equipment is shown in Fig. 2.
3 −6 3 2
mPa·s) flows through it at a rate of 1 cm /s (10 m /s)/1 cm
−4 2
(10 m )cross-sectionalareaatapressuredifferentialof1atm
(101.4kPa)/1cm(10mm)oflength.Onedarcycorrespondsto
0.987 µm . For water as the flowing fluid at 20°C, a hydraulic
conductivity of 9.66 µm/s corresponds to a permeability of 1
darcy.
NOTE 1—A darcy (or darcy unit) and millidarcy (md or mD) are units
of permeability. They are not SI units, but are widely used in petroleum
engineering and geology. A darcy has dimensional units in length.
5.5.2 Viscosity of Water—Table 1 shows the viscosity of
water as a function of temperature.
NOTE 2—The quality of the result produced by this standard is
dependent on the competence of the personnel performing it and the
suitability of the equipment and facility used. Agencies that meet the
criteria of Practice D3740 are generally considered capable of competent
and objective testing/sampling/observation/ and the like. Users of this
standardarecautionedthatcompliancewithPracticeD3740doesnotitself
guaranteereliableresults.Reliableresultsdependonmanyfactors;D3740
provides a means of evaluating some of those factors.
NOTE 3—The function of wells in any unconfined setting in a fractured
terrain might make the determination of k problematic because the wells
might only intersect tributary or subsidiary channels or conduits. The
problems determining the k of a channel or conduit notwithstanding, the
partial penetration of tributary channels may make determination of a
meaningfulnumberdifficult.Ifplotsofkincarbonatesandotherfractured
settings are made and compared, they may show no indication that there
are conduits or channels present, except when with the lowest probability
one maybe intersected by a borehole and can be verified, such problems
are described by Worthington (3) Smart, 1999 (4). Additional guidance
can be found in D5717. FIG. 2 Schematic of Test Equipment
D4631 − 18
7.1 Source of Pressure Pulse—A pump or pressure intensi- 8.1.4 Core Description—Describe the rock core from the
fier shall be capable of injecting an additional amount of water test holes with particular emphasis on the lithology and natural
to the water-filled tubing string and packed-off test interval to discontinuities.
produce a sharp pressure pulse of up to 1 MPa (145 psi) in 8.1.5 Geophysical Borehole Logging—Log geophysically
magnitude, preferably with a rise time of less than 1% of one
the zones of potential interest. In particular, run electrical-
half of the pressure decay (P/P =0.5). induction and gamma-gamma density logs. Run other logs as
o
needed.
7.2 Packers—Hydraulically actuated packers are recom-
8.1.6 Washing Test Holes—The test holes must not contain
mended because they produce a positive seal on the borehole
material when practicable that could be washed into the
wall and because of the low compressibility of water they are
permeablezonesduringtesting,therebychangingthetransmis-
alsocomparativelyrigid.Eachpackershallsealaportionofthe
sivityandstorativity.Flushthetestholeswithcleanwateruntil
boreholewall0.5minlengthormore,withanappliedpressure
the return is free from cuttings and other dispersed solids.
equal to the excess maximum pulse pressure or more to be
applied to the packed-off interval and less than the formation 8.2 Test Intervals:
fracture pressure at that depth.
8.2.1 Selection of Test Intervals—Test intervals are deter-
mined from the core descriptions, geophysical borehole logs,
7.3 Pressure Transducers—The test pressure may be mea-
and, if necessary, from visual inspection of the borehole with a
sured directly in the packed-off test interval or between the
borescope or television camera.
fast-acting valve and the test interval with an electronic
8.2.2 Changes in Lithology—Test each major change in
pressure transducer. In either case the pressure shall be
lithology that can be isolated between packers.
recorded at the surface as a function of time. The pressure
8.2.3 Sampling Discontinuities—Discontinuities are often
transducer shall have an accuracy when practicable of 63 kPa
the major permeable features in hard rock. Test jointed zones,
(60.4 psi), including errors introduced by the recording
fault zones, bedding planes, and the like, both by isolating
system, and a resolution when practicable of 1 kPa (0.15 psi).
individual features and by evaluating the combined effects of
7.4 Hydraulic Systems—The inflatable rubber packers shall
several features.
be attached to high-pressure steel tubing reaching to the
8.2.4 Redundancy of Tests—To evaluate variability in trans-
surface. The packers themselves shall be inflated with water
missivity and storativity, conduct several tests in each rock
using a separate hydraulic system. The pump or pressure
type,ifhomogeneous.Iftherockisnothomogeneous,eachset
intensifier providing the pressure pulse shall be attached to the
of tests should encompass similar types of discontinuities.
steeltubingatthesurface.Ifthepumpisused,afast-operating
8.3 Test Water:
valve shall be located above, but as near as practical to the
8.3.1 Water Quality—Water used for pressure pulse tests
upper packer. That valve should be located less than 10 m
shall be clean and compatible with the formation. Even small
above the anticipated equilibrium head in the interval being
amounts of dispersed solids in the injection water could plug
testedtoavoidconditionsinthetubingchangingduringthetest
the rock face of the test interval and result in a measured
from a full water column to a falling water-level column
transmissivity value that is erroneously low. Potable water is
because of formation of a free surface at or near zero absolute
generally acceptable.
pressure (Neuzil (5)).
8.3.2 Temperature—The lower limit of the test water tem-
7.5 Water—Waterusedinthistestshallbepotable.Itwillbe
perature shall be 5°C below that of the rock mass to be tested.
clean and compatible with the formation without dispersed
Cold water injected into a warm rock mass causes air to come
solids.
out of solution, and the resulting bubbles will radically modify
the pressure transient characteristics.
8. Procedure
8.4 Testing:
8.1 Drilling Test Holes:
8.4.1 Filling and Purging System—Allow time after wash-
8.1.1 Number and Orientation—The number of test holes
ing the test hole for induced formation pressures to dissipate.
shall be sufficient to supply the detail needed by the scope of
Once the packers have been set, slowly fill the tubing string
the project. The test holes shall be directed to intersect major
and packed-off interval with water to make sure that air
fracture sets, preferable at right angles.
bubbles will not be trapped in the test interval and tubing.
8.1.2 Test Hole Quality—The drilling procedure shall pro-
8.4.2 Pressure Pulse Test—This range of pressures is in
vide a borehole sufficiently smooth for packer seating, shall
most cases sufficiently low to reduce the potential for the
contain no rapid changes in direction, and shall minimize
distortionoffracturesadjacenttothetesthole,butthepressure
formation damage.
shouldnote
...