ASTM D4520-03(2008)

Standard Practice for Determining Water Injectivity Through the Use of On-Site Floods

SIGNIFICANCE AND USE
The injectivity of a water is best determined by measurements as near to the well as possible to minimize changes in water properties due to air contact and time. This practice describes how core flow tests are carried out near the well.
This practice permits the differentiation of permeability losses from the effects of chemical interaction of water and rock and from the effects of plugging by suspended solids. The procedure can be utilized to estimate the chemical and filtration requirements for the full-scale injection project.
Application of the test results to injection wells requires consideration of test core selection and geometry effects.
This practice as described assumes that the water does not contain free oil or other immiscible hydrocarbons. The presence of free oil would require the method to be modified to account for the effect of oil saturation in the test cores on the water permeability.
SCOPE
1.1 This practice covers a procedure for conducting on-site core flood tests to determine the filtration and chemical treatment requirements for subsurface injection of water. ,  
1.2 This practice applies to water disposal, secondary recovery, and enhanced oil recovery projects and is applicable to injection waters with all ranges of total dissolved solids contents.
1.3 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Apr-2008
• ICS: 13.080.40 - Hydrological properties of soils
• Technical Committee: D19 - Water
• Drafting Committee: D19.05 - Inorganic Constituents in Water

Relations

• Replaces: ASTM D4520-03 - Standard Practice for Determining Water Injectivity Through the Use of On-Site Floods
• Effective Date: 01-May-2008
• Replaced By: ASTM D4520-13 - Standard Practice for Determining Water Injectivity Through the Use of On-Site Floods
• Effective Date: 01-Jan-2013

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D4520 − 03(Reapproved 2008)
Standard Practice for
Determining Water Injectivity Through the Use of On-Site
Floods
This standard is issued under the fixed designation D4520; 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 2.2 American Petroleum Institute Standards:
API RP27 Recommended Practice for Determining Perme-
1.1 This practice covers a procedure for conducting on-site
ability of Porous Media
core flood tests to determine the filtration and chemical
API RP40 Recommended Practice for Core-Analysis Pro-
2, 3
treatment requirements for subsurface injection of water.
cedure
1.2 This practice applies to water disposal, secondary
recovery, and enhanced oil recovery projects and is applicable
3. Terminology
to injection waters with all ranges of total dissolved solids
3.1 Definitions:
contents.
3.1.1 For definitions of terms relating to water and water
1.3 This standard does not purport to address all of the
chemistry, refer to Terminology D1129. Refer to Terminology
safety concerns, if any, associated with its use. It is the
D653 for definitions relating to soil and rock
responsibility of the user of this standard to establish appro-
3.2 Definitions of Terms Specific to This Standard:
priate safety and health practices and determine the applica-
3.2.1 filtration requirement—the maximum suspended sol-
bility of regulatory limitations prior to use.
ids size (in micrometres) allowed in an injection water to
minimize formation plugging.
2. Referenced Documents
3.2.2 test core—a sample cut from a full core that has been
2.1 ASTM Standards:
recovered from the formation into which water is injected.
D420 Guide to Site Characterization for Engineering Design
3.2.3 permeability—the capacity of a rock (or other porous
and Construction Purposes (Withdrawn 2011)
medium) to conduct liquid or gas. It is measured as the
D653 Terminology Relating to Soil, Rock, and Contained
proportionality constant between flow velocity and hydraulic
Fluids
gradient.
D1129 Terminology Relating to Water
3.2.4 pore volume—the volid volume of a porous medium
D2434 Test Method for Permeability of Granular Soils
that can be saturated with the transmitted fluid.
(Constant Head)
D4404 Test Method for Determination of Pore Volume and
3.2.5 porosity—the ratio, usually expressed as a percentage
Pore Volume Distribution of Soil and Rock by Mercury
of the volume of voids of a given soil, rock mass, or other
Intrusion Porosimetry
porous medium to the total volume of the soil, rock mass, or
other porous medium.
3.2.6 rock-water interaction—a reaction between a porous
This practice is under the jurisdiction of ASTM Committee D19 on Water and
rock and the injected water causing precipitation or swelling or
is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents in
release of fines (clays) within the rock.
Water.
Current edition approved May 1, 2008. Published May 2008. Originally
approved in 1986. Last previous edition approved in 2003 as D4520 – 03. DOI: 4. Summary of Practice
10.1520/D4520-03R08.
4.1 This practice assumes that the injection water has been
Farley,J.T.,andRedline,D.G.,“EvaluationofFloodWaterQualityintheWest
Montalvo Field,” Journal Petroleum Technology, July 1968, pp. 683–687.
characterized in terms of dissolved and suspended solids
McCune, C. C., “On-Site Testing to Define Injection Water Quality
contents (including hydrocarbons and other organics as appli-
Requirements,” Journal Petroleum Technology, January 1977, pp. 17–24.
cable) by established standard practices and methods.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
5 6
The last approved version of this historical standard is referenced on Available from American Petroleum Institute (API), 1220 L. St., NW,
www.astm.org. Washington, DC 20005-4070, http://www.api.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4520 − 03 (2008)
4.2 Test core material is selected by consultation between 6.2 Rock-water interactions are more common in sand-
geologists and engineers and prepared for the tests by standard stones than in carbonate rocks. However, within carbonate
practices. rocks dissolved iron in the injection water may precipitate
especially in the presence of dissolved oxygen. Alkaline
4.3 In the on-site core flood the permeability of the test core
precipitates(CaCO andMg(OH) )mayalsoformincarbonate
3 2
is monitored to detect interactions between the formation rock
rocks.
and the injection water.The water is filtered at various levels to
6.2.1 Dissolved hydrogen sulfide in the presence of dis-
determine the filtration required (in micrometres) to minimize
solved iron and oxygen can also be a problem in waters
permeability loss (damage) from suspended solids. Backflow-
injected into carbonate and sandstones resulting in precipita-
ing injection wells are simulated by reversing the flow direc-
tion of sulfides and hydroxides of iron.
tion through the cores.
6.3 The iron and alkaline precipitates described in 6.2 can
5. Significance and Use
also form from waters injected into sandstones. Swelling type
5.1 The injectivity of a water is best determined by mea-
clays (montmorillonite and mixed layer clays) and dispersible
surements as near to the well as possible to minimize changes
clays (kaolinite and chlorite) are potential sources of perme-
in water properties due to air contact and time. This practice
ability losses due to changes in salinity or ionic content of the
describes how core flow tests are carried out near the well.
injected water compared to the natural waters in the formation.
5.2 This practice permits the differentiation of permeability
In some sandstones fine mica particles have been caused to
losses from the effects of chemical interaction of water and
migrate by the injection of a potassium ion deficient water.
rock and from the effects of plugging by suspended solids. The
6.4 In some instances in both sandstones and carbonates
procedurecanbeutilizedtoestimatethechemicalandfiltration
some fine particles are released to migrate as a result of water
requirements for the full-scale injection project.
saturating the cleaned and dried test cores.
5.3 Application of the test results to injection wells requires
consideration of test core selection and geometry effects.
7. Apparatus
5.4 This practice as described assumes that the water does
7.1 A schematic diagram of the test apparatus is shown in
not contain free oil or other immiscible hydrocarbons. The
Fig. 1. The component parts are assembled from commercially
presence of free oil would require the method to be modified to
available laboratory apparatus with the exception of the core
account for the effect of oil saturation in the test cores on the
holders (Fig. 2). While four cores are shown in Fig. 1 the
water permeability.
number used in a test is optional. The apparatus essentially
consists of a filtration section and a core flood section. The
6. Sources of Rock-Water Interactions
various components are connected with plastic or stainless
6.1 Water injected into a porous rock may interact with the
steel flow lines with required valves and gauges as illustrated.
rock to reduce the permeability as a result of the formation of
precipitates, clay swelling, clay dispersion, or the migration of 7.2 The filtration section is assembled from four cartridge
filter holders mounted two each in series. Valves are installed
other fine solids.
FIG. 1 Schematic of Test Equipment
D4520 − 03 (2008)
FIG. 2 Schematic Diagram of Sample Holder
to permit flow through either filter pair or to bypass the filters. 7.8.2 Assorted beakers (250 to 1000 mL),
Pressure gauges are included for monitoring the inlet and
7.8.3 Assorted graduated cylinders (10 to 100 mL),
discharge pressure of the filters. Commercial filters are avail-
7.8.4 Stopwatch,
ablewithratingsrangingaslowas0.2µm.Theratedsizesused
7.8.5 Vacuum tubing, and
in the on-site core flood tests generally range from 0.45 to 10
7.8.6 Assorted tools for assembling and disassembling the
µm.The filter holders should be provided with vents to saturate
equipment as required.
the filters and purge air from the system.
7.3 The core flood section of the apparatus consists of a
8. Procedure
laboratory constant temperature bath rated for up to 150°C
8.1 Core Selection:
(302°F) and of adequate capacity to hold up to four core
holders (Fig. 2). Necessary valves and gauges are provided.As
8.1.1 Choose proper core samples to yield the most mean-
shown in Fig. 1, two of the core holders (No. 1 and No. 2) are ingful test results through close coordination with geologists,
plumbed to allow the flow through the cores to be reversed
chemists, and engineers responsible for the water injection
without removing the core holders. The pressure to the core project.
flood section is controlled with a regulator, and a test gauge is
8.1.2 To assist in that choice include well logs, mineralogy,
used to accurately monitor the test core inlet pressure. The test
porosity, pore size distribution, permeability, and other core
core discharge pressure is atmospheric when the apparatus is
descriptive data.
assembled as shown in Fig. 1.
8.1.3 Choose test cores to represent the zones that will
7.3.1 Another option is to control the discharge at a pressure
receive the injected water. The best samples are from whole
above atmospheric by the addition of a regulator on each core
cores cut from those zones. Prepare sufficient samples to
sample discharge line. This option is recommended if the
represent the ranges of permeability, porosity, and mineralogy
evolution of dissolved gas is anticipated from the water as it
of the injected zones. Consider the presence of natural frac-
flows through the test core.
tures.
7.4 An alternative to the core holders (Fig. 2) is a Hassler-
8.1.4 Select the number and properties of the cores for a
type permeability cell (API RP40) which uses a rubber or
particular test according to one of the following options:
plastic sleeve to form the seal around the core sample. A
8.1.4.1 Use cores having similar properties (porosity, per-
high-pressure air (nitrogen) or liquid supply to maintain the
meability, mineralogy, etc.). Average the results.
seal would be required.
8.1.4.2 Use a set of cores with one of these properties
7.5 The operating gauge pressure of the test apparatus is
different in each core to test the effect of this property on the
usually 700 kPa (100 psig) or less.
test results.
7.6 As shown in Fig. 1, facilities may also be provided for 8.1.5 If cores from the flooded zone are not available,
the addition of chemicals to the water being tested.Achemical choose another zone with similar properties as the next best
supply tank and an injection pump with pressure and flow alternative sample source. As a third choice use synthetic core
ratings corresponding to specific needs would be required. material (alumina, silica, porous glass, etc.).
7.7 The apparatus is attached to a line carrying the water
8.2 Core Sample Preparation:
being tested. Usually, the line pressure of the water source
8.2.1 Follow the recommended procedures for core han-
(regulated as required) satisfies the pressure requirement for
dling, preservation, cutting, and cleaning described in API
flowing the water through the filters and test cores. If the
RP40. (This extensive document describes various procedures
supply pressure is insufficient, a small pump capable of
and options that the investigator may choose depending on the
delivering about 1 L/min at 700 kPa is used.
type and condition of the cores being tested.) Related ASTM
7.8 Other required apparatus are the following: standards are Guide D420, Test Method D2434, and Test
7.8.1 Mechanical (non-aspirator type) vacuum pump, Method D4404.
D4520 − 03 (2008)
8.2.2 The preferred sample dimensions for the core flood 8.3.9 This procedure assumes sample cores are to be
test are 19 mm (0.75 in.) to 38 mm (1.5 in.) outside diameter vacuum saturated with the same water used in the core flood
with a minimum length to diameter ratio of 1:0. test. If a special water or brine is to be used as the saturating
fluid, the procedure is the same, except a valving arrangement
8.2.3 Carry out the following procedure for each core
is needed near the water supply valve to allow for flow of the
sample in the set to be tested:
requiredfluids.Inallcasesfilterthesaturatingfluidto0.45µm.
8.2.3.1 Cut the core sample parallel to the formation bed-
ding plane and then clean by solvent-extraction to remove
8.4 Initial Permeability Measurement :
residual hydrocarbons and water from the pore space. Dry the
8.4.1 The initial permeability of the test core with 0.45-µm
sample and determine the porosity according to the recom-
filtered water is the base value to which permeability changes
mended procedures in API RP40.
are compared.
8.2.3.2 Use the air permeability of the core sample as a
8.4.2 Followtheproceduresin8.1-8.3sothatthecoreshave
guide for choosing representative samples of the formation
been mounted, vacuum saturated, and under pressure and
being tested. The procedure for measuring air permeabilities is
0.45-µm filtered water is available upstream of the test cores.
described in API RP27.
Set and allow the constant temperature bath to become
8.2.3.3 Seal the core sample with an epoxy resin or other
stabilized at the test temperature. (Use water in the bath if the
suitable sealant in a metal (stainless steel, aluminum, brass)
test temperature is less than 80°C (176°F). Use another heating
tube having an inside diameter about 6.4 mm (0.25 in.) larger
medium such as silicone oil at higher temperatures.)
than the outside diameter of the sample.
8.4.3 Open the valve-to-waste downstream of the regulator
8.2.3.4 Machine the ends of the core sample and metal tube
momentarily to check flow.
flat and perpendicular to the tube axis. Generally a stream of
8.4.4 Open the valves to the test cores. Place a 500-mL
compressed air on the core ends during machining will prevent
beaker under the discharge tube from each core holder. Open
the intrusion of fines into the rock pores. the valves at the effluent end of each test core.
8.2.3.5 Mount the metal tube (containing the
...

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:D 4520–95 (Reapproved 1999) Designation:D4520–03 (Reapproved 2008)
Standard Practice for
Determining Water Injectivity Through the Use of On-Site
Floods
This standard is issued under the fixed designation D 4520; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers a procedure for conducting on-site core flood tests to determine the filtration and chemical treatment
2, 3
requirements for subsurface injection of water.
1.2 This practice applies to water disposal, secondary recovery, and enhanced oil recovery projects and is applicable to injection
waters with all ranges of total dissolved solids contents.
1.3 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D 420 Guide to Site Characterization for Engineering, Design, and Construction Purposes
D 653 Terminology Relating to Soil, Rock, and Contained Fluids
D 1129 Terminology Relating to Water
D 2434Test Method for Permeability of Granular Soils (Constant Head)
D3370Practices for Sampling Water from Closed Conduits Test Method for Permeability of Granular Soils (Constant Head)
D 4404 Test Method for Determination of Pore Volume and Pore Volume Distribution of Soil and Rock by Mercury Intrusion
Porosimetry
2.2 American Petroleum Institute Standards:
API RP27 Recommended Practice for Determining Permeability of Porous Media
API RP40 Recommended Practice for Core-Analysis Procedure
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms relating to water and water chemistry, refer to Terminology D 1129. Refer to Terminology D 653
for definitions relating to soil and rock.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 filtration requirement—the maximum suspended solids size (in micrometres) allowed in an injection water to minimize
formation plugging.
3.2.2 test core—a sample cut from a full core that has been recovered from the formation into which water is injected.
3.2.3 permeability—the capacity of a rock (or other porous medium) to conduct liquid or gas. It is measured as the
proportionality constant between flow velocity and hydraulic gradient.
3.2.4 pore volume—the volid volume of a porous medium that can be saturated with the transmitted fluid.
3.2.5 porosity—the ratio, usually expressed as a percentage of the volume of voids of a given soil, rock mass, or other porous
medium to the total volume of the soil, rock mass, or other porous medium.
This practice is under the jurisdiction of ASTM Committee D-19D19 on Water and is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents in
Water.
Current edition approved Sept. 10, 1995.May 1, 2008. Published November 1995.May 2008. Originally published as D4520–86.approved in 1986. Last previous edition
D4520–86(1991). approved in 2003 as D 4520 – 03.
Farley, J. T., and Redline, D. G., “Evaluation of Flood Water Quality in the West Montalvo Field,” Journal Petroleum Technology, July 1968, pp. 683–687.
McCune, C. C., “On-Site Testing to Define Injection Water Quality Requirements,” Journal Petroleum Technology, January 1977, pp. 17–24.
Annual Book of ASTM Standards, Vol 04.08.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Annual Book of ASTM Standards, Vol 11.01.
Available from American Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, http://www.api.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4520–03 (2008)
3.2.6 rock-water interaction—a reaction between a porous rock and the injected water causing precipitation or swelling or
release of fines (clays) within the rock.
4. Summary of Practice
4.1 This practice assumes that the injection water has been characterized in terms of dissolved and suspended solids contents
(including hydrocarbons and other organics as applicable) by established standard practices and methods.
4.2 Test core material is selected by consultation between geologists and engineers and prepared for the tests by standard
practices.
4.3 In the on-site core flood the permeability of the test core is monitored to detect interactions between the formation rock and
the injection water. The water is filtered at various levels to determine the filtration required (in micrometres) to minimize
permeability loss (damage) from suspended solids. Backflowing injection wells are simulated by reversing the flow direction
through the cores.
5. Significance and Use
5.1 The injectivity of a water is best determined by measurements as near to the well as possible to minimize changes in water
properties due to air contact and time. This practice describes how core flow tests are carried out near the well.
5.2 This practice permits the differentiation of permeability losses from the effects of chemical interaction of water and rock
and from the effects of plugging by suspended solids. The procedure can be utilized to estimate the chemical and filtration
requirements for the full-scale injection project.
5.3 Application of the test results to injection wells requires consideration of test core selection and geometry effects.
5.4 This practice as described assumes that the water does not contain free oil or other immiscible hydrocarbons. The presence
of free oil would require the method to be modified to account for the effect of oil saturation in the test cores on the water
permeability.
6. Sources of Rock-Water Interactions
6.1 Water injected into a porous rock may interact with the rock to reduce the permeability as a result of the formation of
precipitates, clay swelling, clay dispersion, or the migration of other fine solids.
6.2 Rock-water interactions are more common in sandstones than in carbonate rocks. However, within carbonate rocks
dissolved iron in the injection water may precipitate especially in the presence of dissolved oxygen.Alkaline precipitates (CaCO
and Mg(OH) ) may also form in carbonate rocks.
6.2.1 Dissolved hydrogen sulfide in the presence of dissolved iron and oxygen can also be a problem in waters injected into
carbonate and sandstones resulting in precipitation of sulfides and hydroxides of iron.
6.3 The iron and alkaline precipitates described in 6.2 can also form from waters injected into sandstones. Swelling type clays
(montmorillonite and mixed layer clays) and dispersible clays (kaolinite and chlorite) are potential sources of permeability losses
duetochangesinsalinityorioniccontentoftheinjectedwatercomparedtothenaturalwatersintheformation.Insomesandstones
fine mica particles have been caused to migrate by the injection of a potassium ion deficient water.
6.4 Insomeinstancesinbothsandstonesandcarbonatessomefineparticlesarereleasedtomigrateasaresultofwatersaturating
the cleaned and dried test cores.
7. Apparatus
7.1 A schematic diagram of the test apparatus is shown in Fig. 1. The component parts are assembled from commercially
available laboratory apparatus with the exception of the core holders (Fig. 2). While four cores are shown in Fig. 1 the number
used in a test is optional.The apparatus essentially consists of a filtration section and a core flood section.The various components
are connected with plastic or stainless steel flow lines with required valves and gauges as illustrated.
7.2 The filtration section is assembled from four cartridge filter holders mounted two each in series. Valves are installed to
permit flow through either filter pair or to bypass the filters. Pressure gauges are included for monitoring the inlet and discharge
pressure of the filters. Commercial filters are available with ratings ranging as low as 0.2 µm. The rated sizes used in the on-site
corefloodtestsgenerallyrangefrom0.45to10µm.Thefilterholdersshouldbeprovidedwithventstosaturatethefiltersandpurge
air from the system.
7.3 The core flood section of the apparatus consists of a laboratory constant temperature bath rated for up to 150°C (302°F) and
of adequate capacity to hold up to four core holders (Fig. 2). Necessary valves and gauges are provided.As shown in Fig. 1, two
of the core holders (No. 1 and No. 2) are plumbed to allow the flow through the cores to be reversed without removing the core
holders. The pressure to the core flood section is controlled with a regulator, and a test gauge is used to accurately monitor the test
core inlet pressure. The test core discharge pressure is atmospheric when the apparatus is assembled as shown in Fig. 1.
7.3.1 Another option is to control the discharge at a pressure above atmospheric by the addition of a regulator on each core
sample discharge line. This option is recommended if the evolution of dissolved gas is anticipated from the water as it flows
through the test core.
7.4 An alternative to the core holders (Fig. 2) is a Hassler-type permeability cell (API RP40) which uses a rubber or plastic
sleeve to form the seal around the core sample. A high-pressure air (nitrogen) or liquid supply to maintain the seal would be
required.
D4520–03 (2008)
FIG. 1 Schematic of Test Equipment
FIG. 2 Schematic Diagram of Sample Holder
7.5 The operating gauge pressure of the test apparatus is usually 700 kPa (100 psig) or less.
7.6 AsshowninFig.1,facilitiesmayalsobeprovidedfortheadditionofchemicalstothewaterbeingtested.Achemicalsupply
tank and an injection pump with pressure and flow ratings corresponding to specific needs would be required.
7.7 The apparatus is attached to a line carrying the water being tested. Usually, the line pressure of the water source (regulated
as required) satisfies the pressure requirement for flowing the water through the filters and test cores. If the supply pressure is
insufficient, a small pump capable of delivering about 1 L/min at 700 kPa is used.
7.8 Other required apparatus are the following:
7.8.1 Mechanical (non-aspirator type) vacuum pump,
7.8.2 Assorted beakers (250 to 1000 mL),
7.8.3 Assorted graduated cylinders (10 to 100 mL),
7.8.4 Stopwatch,
7.8.5 Vacuum tubing, and
7.8.6 Assorted tools for assembling and disassembling the equipment as required.
8. Procedure
8.1 Core Selection:
8.1.1 Choosepropercoresamplestoyieldthemostmeaningfultestresultsthroughclosecoordinationwithgeologists,chemists,
and engineers responsible for the water injection project.
8.1.2 To assist in that choice include well logs, mineralogy, porosity, pore size distribution, permeability, and other core
descriptive data.
D4520–03 (2008)
8.1.3 Choose test cores to represent the zones that will receive the injected water. The best samples are from whole cores cut
fromthosezones.Preparesufficientsamplestorepresenttherangesofpermeability,porosity,andmineralogyoftheinjectedzones.
Consider the presence of natural fractures.
8.1.4 Select the number and properties of the cores for a particular test according to one of the following options:
8.1.4.1 Use cores having similar properties (porosity, permeability, mineralogy, etc.). Average the results.
8.1.4.2 Use a set of cores with one of these properties different in each core to test the effect of this property on the test results.
8.1.5 If cores from the flooded zone are not available, choose another zone with similar properties as the next best alternative
sample source. As a third choice use synthetic core material (alumina, silica, porous glass, etc.).
8.2 Core Sample Preparation:
8.2.1 Follow the recommended procedures for core handling, preservation, cutting, and cleaning described inAPI RP40. (This
extensivedocumentdescribesvariousproceduresandoptionsthattheinvestigatormaychoosedependingonthetypeandcondition
of the cores being tested.) Related ASTM standards are Guide D 420, Test Method D 2434, and Test Method D 4404.
8.2.2 The preferred sample dimensions for the core flood test are 19 mm (0.75 in.) to 38 mm (1.5 in.) outside diameter with
a minimum length to diameter ratio of 1:0.
8.2.3 Carry out the following procedure for each core sample in the set to be tested:
8.2.3.1 Cut the core sample parallel to the formation bedding plane and then clean by solvent-extraction to remove residual
hydrocarbonsandwaterfromtheporespace.Drythesampleanddeterminetheporosityaccordingtotherecommendedprocedures
in API RP40.
8.2.3.2 Use the air permeability of the core sample as a guide for choosing representative samples of the formation being tested.
The procedure for measuring air permeabilities is described in API RP27.
8.2.3.3 Seal the core sample with an epoxy resin or other suitable sealant in a metal (stainless steel, aluminum, brass) tube
having an inside diameter about 6.4 mm (0.25 in.) larger than the outside diameter of the sample.
8.2.3.4 Machine the ends of the core sample and metal tube flat and perpendicular to the tube axis. Generally a stream of
compressed air on the core ends during machining will prevent the intrusion of fines into the rock pores.
8.2.3.5 Mount the metal tube (containing the core sample) in a holder designed to allow water to be flowed through the sample.
An example of such a sample holder is shown schematically in Fig. 2.
8.3 Vacuum Saturation of Test Cores :
8.3.1 Install a 10-µm rated cartridge in filter No. 1 and a 0.45-µm cartridge in filter No. 2. Close valves to and from filters No.
3 and No. 4, the filter bypass valve, and valves to all core sample holders.
8.3.2 Open the valve-to-waste upstream and downstream of the regulator and the valves to and from filters No. 1 and No. 2.
Start water flow through the filters to waste.
8.3.3 Close the valve-to-waste upstream of the pressure regulator. Set the regulator at about 120 kPa (17 psi) more than the
pressure planned for the test. After about 2 min, close the valve-to-waste downstream of the regulator.
8.3.4 Mount from one to four sample cores in the holders (lines should not contain wa
...