1、Designation: D4525 132Standard Test Method forPermeability of Rocks by Flowing Air1This standard is issued under the fixed designation D4525; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pa
2、rentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial corrections were made throughout in February 2014.2NOTEEditorially updated units of measurement statement in April 2018.1. Scope*1.1 This test m
3、ethod covers the determination of the coef-ficient of specific permeability for the flow of air throughrocks. The method establishes representative values of thecoefficient of permeability of rocks or well-indurated soils.1.2 This test method is limited to permeability valuesgreater than 9.869 10-18
4、m2(0.01 millidarcy), and is limitedto rocks free of oil or unctuous matter.1.3 The values stated in SI units are to be regarded asstandard. The values given in parentheses after SI units areprovided for information only and are not considered standard.Reporting of test results in units other than SI
5、 shall not beregarded as nonconformance with this test method.1.4 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.4.1 The procedures used to specify how data are collected/recorded or calculated, in this standard ar
6、e regarded as theindustry standard. In addition, they are representative of thesignificant digits that generally should be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives; and i
7、t is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analyticalmethods for engineering design.1.5 This standard does not purport to address all of thesa
8、fety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-da
9、nce with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM St
10、andards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD6026 Practice for Using Significant Digits in GeotechnicalData2.2 American Petr
11、oleum Institute Standard:3RP-40 Recommended Practice for Core Analysis Procedure3. Terminology3.1 DefinitionsFor definitions of common technical termsin this standard, refer to Terminology D653.4. Summary of Test Method4.1 The permeability of a rock sample is measured byflowing dry air through the s
12、pecimen and measuring theabsolute pressure, the flow rate, and absolute pressure differ-ential of the air. Three or more tests are performed on a sampleat different mean air pressure values. The permeability valuesare plotted as a function of the reciprocal mean absolutepressure; those points lying
13、on a straight line are extrapolatedto a value corresponding to an infinite mean air pressure toobtain an equivalent permeability value for liquids.5. Significance and Use5.1 This test method is designed to measure the permeabil-ity to air of a small sample of rock. By extrapolation, this test1This t
14、est method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved in 1985. Last previous edition approved in 2008 as D4525 08. DOI:10.1
15、520/D4525-13E02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Petroleum Institute
16、(API), 1220 L. St., NW,Washington, DC 20005-4070, http:/www.api.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordanc
17、e with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1method also determines an equivalent
18、 of the liquid permeabil-ity. This parameter is used to calculate the flow through rock offluids subjected to a pressure differential.NOTE 1The quality of the result produced by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facili
19、ties used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing. Users of this standard are cautioned that compliancewith Practice D3740 does not in itself assure reliable results. Reliableresults depend on many factors; Practice D3740 p
20、rovides a means ofevaluating some of those factors.6. Apparatus6.1 PermeameterThe permeameter shall have a specimenholder; a pressure transducer or gauge, or manometers, formeasuring the air pressure differential across the ends of thespecimen; a means for measuring the flow rate of the air; anda me
21、ans for providing dry air to the flow stream (see Fig. 1).6.1.1 Specimen HolderThe specimen holder shall have adiameter of at least ten times the diameter of the largest particleof the specimen. Where suitable, the preferred diameter is 2.54cm (1 in.). The entrance and exit flow ports shall be suffi
22、cientlylarge to prevent pressure loss at maximum flow rate.The lengthshall be 1.3 to 1.7 times the diameter.6.1.2 Preferred ApparatusIn the preferred form, the speci-men holder shall be an elastomer sleeve and have means forconfining the sleeve and compressing it against the specimenso as to prevent
23、 bypassing of air under pressure between thesleeve and the specimen. The holder shall also have a meansfor confining the ends of the sample. In the preferred form, theend confining plugs will have two ports each, one for the flowof air, and the other for a static pressure line to measurepressure at
24、the end faces of the specimen, as in Fig. 2. This typeof holder is suitable for many types of flowing fluids andallows the simulation of overburden stress on the specimen.6.1.3 Alternative ApparatusAn elastomer bushing may beused to confine the specimen, as in Fig. 3. This holder issuitable for conf
25、ining well-indurated specimens of a fine tomoderate texture. This holder allows rapid operation; it cannotbe used for simulating overburden stress.6.1.3.1 Alternatively, a rigid bushing may be cast around thespecimen (see Fig. 4). The casting material shall be one thatwill adhere well to both the sp
26、ecimen and the bushing, withoutpenetration of the specimen beyond the superficial pores.Epoxies, polyesters, and sealing wax are suitable for thispurpose. This method of mounting samples is particularly wellsuited for testing less well-indurated specimens. This techniqueis not applicable for tests r
27、equiring the simulation of overbur-den stress.6.1.4 The flow rate of the air shall be sensed downstreamfrom the specimen by means of calibrated orifices (Fig. 1),rotameters (Fig. 5), or a bubble meter (Fig. 6).6.1.5 The preferred method of sensing absolute pressure toobtain the pressure differential
28、 across the specimen is by meansof absolute pressure transducers located at the ends of thespecimen. The transducers must operate over a range of 0 to 50kPa (0 to 7.3 psi) with a resolution of 250 Pa (0.036 psi) orbetter. Alternatively, the sensors may be connected to the endfaces of the specimen wi
29、th static lines, or placed in sufficientlylarge flow lines to cause less than 250 Pa (0.036 psi) loss ofhead at maximum flow rate. Pressure must be sensed betweenthe downstream end of the specimen and the orifice if such aflow sensor is utilized.6.1.5.1 Manometers may be utilized to measure the pres
30、-sures of the flowing air. Both mercury and water manometersmust be provided with a high-pressure cutoff valve to the waterFIG. 1 Air Permeameter (Reproduced from RP-40)FIG. 2 Hassler Type Specimen Holder FIG. 3 Fancher-Type Specimen HolderD4525 1322manometer as in Fig. 1, to provide the range of di
31、fferentialpressures required. The manometers must be 20 cm (7.9 in.) ormore in height.6.1.5.2 Alternatively, absolute pressure gages with a rangeof 0 to 50 kPa (0 to 7.3 psi) and a resolution of 250 Pa (0.036psi) may be used to measure the pressure of the flowing air.6.1.6 The dimensions of the colu
32、mn for drying the flowingair shall be a 2.54 cm (1 in.) inside diameter by a 30 cm (11.8in.) or more length. The columns shall be filled with silica gelor anhydrous calcium sulfate, with indicator. There shall be ascreen of 50 mesh on the downstream end of the filter toprevent particulate matter fro
33、m reaching the specimen undertest.6.1.7 Compressed Air SourceA source with a regulatorand gauge that shall supply air pressure up to 50 kPa (7.3 psi)for the flow system.6.1.7.1 The air shall be clean and free of particles that canplug the pores of the sample.6.1.7.2 A compressed air supply with a se
34、parate regulatorand gauge, or a hydraulic pressure source with gauge, shallsupply pressure for seating the sleeve when that option forholding the specimen is used. A seating pressure of 700 kPa(101.5 psi) or more shall be used for seating. Pressures up to100 MPa (14503.8 psi) may be required for sim
35、ulating in situstress.6.1.8 Small Vacuum SourceUsed for expanding thesleeve-type holder is required for specimen insertion when thatholder option is utilized.6.2 Drilling MachineA machine with a diamond bit andcoolant circulating system to drill specimens from rocksamples.6.3 Required Miscellaneous
36、ImplementsItems including astop watch for use with bubble meter, a metric scale graduatedin millimetres for manometers, and a thermometer with divi-sions of 0.5C (1F) or better for measuring room temperature.6.4 Specimen Size Measurement DevicesDevices used tomeasure the length and diameter of the s
37、pecimen shall becapable of measuring the desired dimension to within 0.1 % ofits actual length.7. Hazards7.1 WarningMercury has been designated by many regu-latory agencies as a hazardous material that can cause seriousmedical issues. Mercury, or its vapor, may be hazardous tohealth and corrosive to
38、 materials. Caution should be takenwhen handling mercury containing products. See the appli-cable product Safety Data Sheet (SDS) for additional informa-tion. Users should be aware that selling mercury or mercurycontaining products into your state or country may be prohib-ited by law.8. Sampling8.1
39、An adequate supply of homogeneous material is neces-sary. A selection of samples shall be made using visualexamination of the site of evaluation to provide a representa-tive array of permeability values. Attention should be given tothe in situ orientation of the sample when visual inspectionindicate
40、s anisotropy is present. Dip and strike of beddingplanes, if any, should be noted.9. Test Specimens9.1 Drill cylindrical specimens from the rock samples inorientations dictated by the in situ conditions and test goals, forexample, parallel and perpendicular to the bedding planes.Drill the samples to
41、 a length between 1.3 and 1.7 times thediameter of the specimen.FIG. 4 Compression Cell for Ring-Mounted SpecimensFIG. 5 Shielded MicroflowmeterFIG. 6 Bubble MeterD4525 13239.2 The ends of the specimen shall be faced with a diamondsaw to be approximately perpendicular to the axis of thespecimen. Was
42、h the end faces with clear water.9.3 Drying Specimens:9.3.1 If the specimen is free of swelling clay, dry in aconventional oven at a temperature of approximately 100Cuntil an equilibrium weight is obtained. Before weighing, coolspecimens to room temperature in a desiccator. Drying timevaries with sp
43、ecimen size and permeability;4hisgenerallysufficient for a permeable specimen of 2.54 cm (1 in.) indiameter.9.3.2 If the specimen contains swelling clays, dry in acontrolled humidity oven at 45?% relative humidity at 63Cuntil weight equilibrium is obtained. Drying time under theseconditions is usual
44、ly two to four days.9.4 If necessary, clean engrained fines from the end faces ofthe specimen by mild wire brushing and air jetting.10. Procedure10.1 Measure and record the length and diameter of thespecimen to the nearest 0.1 mm (0.004 in.). Take a minimum ofthree length measurements 120 apart and
45、at least threediameter measurements one at the each end and one at themid-point of the height. Determine the average length anddiameter of the specimen.10.2 Place the specimen in the specimen holder and add endpieces to the holder as necessary. Turn the wheel of thecompression apparatus of the bushi
46、ng-type holder, or increasethe annulus pressure of the sleeve-type holder, until a sealagainst the periphery of the specimen is obtained.Apressure of700 kPa (101.5 psi) is usually found sufficient for sealing thesleeve-type holder.Apply additional pressure to the core holderif the simulation of in s
47、itu stress is required.10.3 Open the entrance flow valve, allowing air to flow tothe specimen. Adjust the entrance pressure upward until asuitable flow of air occurs, but do not exceed the criticalvelocity beyond which turbulent flow occurs or inertial effectsbecome significant. Flow rates less than
48、 2 cm3/s per 1 cm2ofspecimen end face area usually are found to be satisfactory.Observe the flow rate until an equilibrium value is attained.Measure and record the flow rate and pressure differentialacross the specimen.10.4 Lower the flowing pressure used in 10.3 to abouttwo-thirds of the value and
49、repeat the test and record.10.5 Lower the flowing pressure used in 10.4 to aboutone-half of the value and repeat the test and record.10.6 Make preliminary calculations of the flow rate dividedby pressure differential of each step: 10.3 10.5. If the valuesare linearly related, proceed to Section 11. If the values are notlinearly related, reduce the flowing pressure in 10.5, repeat thetest, and record.10.7 Repeat the procedures of 10.3 10.6 until a linear setof data is obtained.11. Calculation11.1 Calculate the coefficient of permeability, k, at eachm
