ASTM D4520-95(1999)
(Practice)Standard Practice for Determining Water Injectivity Through the Use of On-Site Floods
Standard Practice for Determining Water Injectivity Through the Use of On-Site Floods
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. 2,3
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
Relations
Standards Content (Sample)
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Designation: D 4520 – 95 (Reapproved 1999)
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 ability of Porous Media
API RP40 Recommended Practice for Core-Analysis Pro-
1.1 This practice covers a procedure for conducting on-site
cedure
core flood tests to determine the filtration and chemical
,
2 3
treatment requirements for subsurface injection of water.
3. Terminology
1.2 This practice applies to water disposal, secondary re-
3.1 Definitions:
covery, and enhanced oil recovery projects and is applicable to
3.1.1 For definitions of terms relating to water and water
injection waters with all ranges of total dissolved solids
chemistry, refer to Terminology D 1129. Refer to Terminology
contents.
D 653 for definitions relating to soil and rock.
1.3 This standard does not purport to address all of the
3.2 Definitions of Terms Specific to This Standard:
safety concerns, if any, associated with its use. It is the
3.2.1 filtration requirement—the maximum suspended sol-
responsibility of the user of this standard to establish appro-
ids size (in micrometres) allowed in an injection water to
priate safety and health practices and determine the applica-
minimize formation plugging.
bility of regulatory limitations prior to use.
3.2.2 test core—a sample cut from a full core that has been
2. Referenced Documents recovered from the formation into which water is injected.
3.2.3 permeability—the capacity of a rock (or other porous
2.1 ASTM Standards:
medium) to conduct liquid or gas. It is measured as the
D 420 Guide to Site Characterization for Engineering, De-
proportionality constant between flow velocity and hydraulic
sign, and Construction Purposes
gradient.
D 653 Terminology Relating to Soil, Rock, and Contained
3.2.4 pore volume—the volid volume of a porous medium
Fluids
that can be saturated with the transmitted fluid.
D 1129 Terminology Relating to Water
3.2.5 porosity—the ratio, usually expressed as a percentage
D 2434 Test Method for Permeability of Granular Soils
of the volume of voids of a given soil, rock mass, or other
(Constant Head)
porous medium to the total volume of the soil, rock mass, or
D 3370 Practices for Sampling Water from Closed Con-
other porous medium.
duits
3.2.6 rock-water interaction—a reaction between a porous
D 4404 Test Method for Determination of Pore Volume and
rock and the injected water causing precipitation or swelling or
Pore Volume Distribution of Soil and Rock by Mercury
4 release of fines (clays) within the rock.
Intrusion Porosimetry
2.2 American Petroleum Institute Standards:
4. Summary of Practice
API RP27 Recommended Practice for Determining Perme-
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 appli-
cable) by established standard practices and methods.
This practice is under the jurisdiction of ASTM Committee D-19 on Water and
4.2 Test core material is selected by consultation between
is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents in
geologists and engineers and prepared for the tests by standard
Water.
Current edition approved Sept. 10, 1995. Published November 1995. Originally practices.
published as D 4520 – 86. Last previous edition D 4520 – 86 (1991).
4.3 In the on-site core flood the permeability of the test core
Farley, J. T., and Redline, D. G., “Evaluation of Flood Water Quality in the West
is monitored to detect interactions between the formation rock
Montalvo Field,” Journal Petroleum Technology, July 1968, pp. 683–687.
McCune, C. C., “On-Site Testing to Define Injection Water Quality Require-
ments,” Journal Petroleum Technology, January 1977, pp. 17–24.
4 6
Annual Book of ASTM Standards, Vol 04.08. Available from American Petroleum Institute, 1220 L St., NW, Washington, DC
Annual Book of ASTM Standards, Vol 11.01. 20005.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4520
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
also form from waters injected into sandstones. Swelling type
5. Significance and Use
clays (montmorillonite and mixed layer clays) and dispersible
5.1 The injectivity of a water is best determined by mea-
clays (kaolinite and chlorite) are potential sources of perme-
surements as near to the well as possible to minimize changes
ability losses due to changes in salinity or ionic content of the
in water properties due to air contact and time. This practice
injected water compared to the natural waters in the formation.
describes how core flow tests are carried out near the well.
In some sandstones fine mica particles have been caused to
5.2 This practice permits the differentiation of permeability
migrate by the injection of a potassium ion deficient water.
losses from the effects of chemical interaction of water and
6.4 In some instances in both sandstones and carbonates
rock and from the effects of plugging by suspended solids. The
some fine particles are released to migrate as a result of water
procedure can be utilized to estimate the chemical and filtration
saturating the cleaned and dried test cores.
requirements for the full-scale injection project.
5.3 Application of the test results to injection wells requires
7. Apparatus
consideration of test core selection and geometry effects.
7.1 A schematic diagram of the test apparatus is shown in
5.4 This practice as described assumes that the water does
Fig. 1. The component parts are assembled from commercially
not contain free oil or other immiscible hydrocarbons. The
available laboratory apparatus with the exception of the core
presence of free oil would require the method to be modified to
holders (Fig. 2). While four cores are shown in Fig. 1 the
account for the effect of oil saturation in the test cores on the
number used in a test is optional. The apparatus essentially
water permeability.
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
steel flow lines with required valves and gages as illustrated.
6.1 Water injected into a porous rock may interact with the
rock to reduce the permeability as a result of the formation of 7.2 The filtration section is assembled from four cartridge
precipitates, clay swelling, clay dispersion, or the migration of filter holders mounted two each in series. Valves are installed
other fine solids. to permit flow through either filter pair or to bypass the filters.
6.2 Rock-water interactions are more common in sand- Pressure gages are included for monitoring the inlet and
stones than in carbonate rocks. However, within carbonate discharge pressure of the filters. Commercial filters are avail-
rocks dissolved iron in the injection water may precipitate able with ratings ranging as low as 0.2 μm. The rated sizes used
especially in the presence of dissolved oxygen. Alkaline in the on-site core flood tests generally range from 0.45 to 10
μm. The filter holders should be provided with vents to saturate
precipitates (CaCO and Mg(OH) ) may also form in carbonate
3 2
rocks. the filters and purge air from the system.
FIG. 1 Schematic of Test Equipment
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D 4520
FIG. 2 Schematic Diagram of Sample Holder
7.3 The core flood section of the apparatus consists of a 8.1.1 Choose proper core samples to yield the most mean-
laboratory constant temperature bath rated for up to 150°C ingful test results through close coordination with geologists,
(302°F) and of adequate capacity to hold up to four core chemists, and engineers responsible for the water injection
holders (Fig. 2). Necessary valves and gages are provided. As project.
shown in Fig. 1, two of the core holders (No. 1 and No. 2) are 8.1.2 To assist in that choice include well logs, mineralogy,
plumbed to allow the flow through the cores to be reversed porosity, pore size distribution, permeability, and other core
without removing the core holders. The pressure to the core descriptive data.
flood section is controlled with a regulator, and a test gage is 8.1.3 Choose test cores to represent the zones that will
used to accurately monitor the test core inlet pressure. The test receive the injected water. The best samples are from whole
core discharge pressure is atmospheric when the apparatus is cores cut from those zones. Prepare sufficient samples to
assembled as shown in Fig. 1. represent the ranges of permeability, porosity, and mineralogy
7.3.1 Another option is to control the discharge at a pressure of the injected zones. Consider the presence of natural frac-
above atmospheric by the addition of a regulator on each core tures.
sample discharge line. This option is recommended if the 8.1.4 Select the number and properties of the cores for a
evolution of dissolved gas is anticipated from the water as it particular test according to one of the following options:
flows through the test core. 8.1.4.1 Use cores having similar properties (porosity, per-
7.4 An alternative to the core holders (Fig. 2) is a Hassler- meability, mineralogy, etc.). Average the results.
type permeability cell (API RP40) which uses a rubber or 8.1.4.2 Use a set of cores with one of these properties
plastic sleeve to form the seal around the core sample. A different in each core to test the effect of this property on the
high-pressure air (nitrogen) or liquid supply to maintain the test results.
seal would be required. 8.1.5 If cores from the flooded zone are not available,
7.5 The operating gage pressure of the test apparatus is choose another zone with similar properties as the next best
usually 700 kPa (100 psig) or less. alternative sample source. As a third choice use synthetic core
7.6 As shown in Fig. 1, facilities may also be provided for material (alumina, silica, porous glass, etc.).
the addition of chemicals to the water being tested. A chemical 8.2 Core Sample Preparation:
supply tank and an injection pump with pressure and flow 8.2.1 Follow the recommended procedures for core han-
ratings corresponding to specific needs would be required. dling, preservation, cutting, and cleaning described in API
7.7 The apparatus is attached to a line carrying the water RP40. (This extensive document describes various procedures
being tested. Usually, the line pressure of the water source and options that the investigator may choose depending on the
(regulated as required) satisfies the pressure requirement for type and condition of the cores being tested.) Related ASTM
flowing the water through the filters and test cores. If the standards are Guide D 420, Test Method D 2434, and Test
supply pressure is insufficient, a small pump capable of Method D 4404.
delivering about 1 L/min at 700 kPa is used. 8.2.2 The preferred sample dimensions for the core flood
7.8 Other required apparatus are the following: test are 19 mm (0.75 in.) to 38 mm (1.5 in.) outside diameter
7.8.1 Mechanical (non-aspirator type) vacuum pump, with a minimum length to diameter ratio of 1:0.
7.8.2 Assorted beakers (250 to 1000 mL), 8.2.3 Carry out the following procedure for each core
7.8.3 Assorted graduated cylinders (10 to 100 mL), sample in the set to be tested:
7.8.4 Stopwatch, 8.2.3.1 Cut the core sample parallel to the formation bed-
7.8.5 Vacuum tubing, and ding plane and then clean by solvent-extraction to remove
7.8.6 Assorted tools for assembling and disassembling the residual hydrocarbons and water from the pore space. Dry the
equipment as required. sample and determine the porosity according to the recom-
mended procedures in API RP40.
8. Procedure
8.2.3.2 Use the air permeability of the core sample as a
8.1 Core Selection: guide for choosing representative samples of the formation
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4520
being tested. The procedure for measuring air permeabilities is Set and allow the constant temperature bath to become
described in API RP27. stabilized at the test temperature. (Use water in the bath if the
test temperature is less than 80°C (176°F). Use another heating
8.2.3.3 Seal the core sample with an epoxy resin or other
suitable sealant in a metal (stainless steel, aluminum, brass) medium such as silicone oil at higher temperatures.)
tube having an inside diameter about 6.4 mm (0.25 in.) larger 8.4.3 Open the valve-to-waste downstream of the regulator
than the outside diameter of the sample.
momentarily to check flow.
8.2.3.4 Machine the ends of the core sample and metal tube
8.4.4 Open the valves to the test cores. Place a 500-mL
flat and perpendicular to the tube axis. Generally a stream of beaker under the discharge tube from each core holder. Open
compressed air on the core ends during machining will prevent
the valves at the effluent end of each test core.
the intrusion of fines into the rock pores.
8.4.5 Reset the upstream pressure, if needed, using the
8.2.3.5 Mount the metal tube (containing the core sample)
regulator. It should be noted that the method described herein
in a holder designed to allow water to be flowed through the
calls for a constant, regulated pressure across the core sample
sample. An example of such a sample holder is shown
during the test. As an alternative use a constant flow pump for
schematically in Fig. 2.
each core.
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