Significance and Use
Canister desorption is a widely used technique to measure the gas content of coal. The gas content data when normalized to volume/weight and multiplied by coal mass is used to estimate the gas in place in an area around the cored well.
1.1 This practice describes methods for the direct determination of the gas content of coal by desorption using samples obtained by drill coring methods from the surface. It sets out guidelines for the equipment construction, sample preparation and testing procedure, and method of calculation.
1.2 Indirect methods for the determination of the gas content of coal (not covered in this practice) are based on either the gas absorption characteristics of coal under a given pressure and temperature condition or other empirical data that relate the gas content of coal to such other parameters as coal rank, depth of cover, or gas emission rate.
1.3 This practice covers the following two direct methods, which vary only in the time allowed for the gas to desorb from the core, or sidewall core, before final crushing:
1.3.1 The slow desorption method in which volumetric readings of gas content are taken frequently (for example, every 10 to 15 min) during the first few hours, followed by hourly measurements for several hours, and then measurements on 24-h intervals until no or very little gas is being desorbed for an extended period of time.
1.3.2 The fast desorption method in which after initial desorbed gas measurements to obtain data for lost gas calculations, the canister is opened and the sample is transferred to the coal crusher. The remaining gas volume is measured on a crushed sample.
1.4 This practice is confined to the direct method using core, or sidewall core obtained from drilling. The practice can be applied to drill cuttings samples; however, the use of cuttings is not recommended because the results may be misleading and are difficult to compare to the results obtained from core desorption. The interpretation of the results does not fall within the scope of the practice.
1.5 Units—The values stated in either SI units or inch-pound units are to be regarded separately as the standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
1.6 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 (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
ISO6706 Plastics laboratory ware--Graduated measuring cylinders Available from the International Organization for Standardization (ISO), 1, rue de Varemb, Case Postale 56, CH-1211 Geneva 20, Switzerland or via the website: http://www.iso.org/.
D121 Terminology of Coal and Coke
D167 Test Method for Apparent and True Specific Gravity and Porosity of Lump Coke
D1412 Test Method for Equilibrium Moisture of Coal at 96 to 97 Percent Relative Humidity and 30C
D2799 Test Method for Microscopical Determination of the Maceral Composition of Coal
D3172 Practice for Proximate Analysis of Coal and Coke
D3173 Test Method for Moisture in the Analysis Sample of Coal and Coke
D3174 Test Method for Ash in the Analysis Sample of Coal and Coke from Coal
D3176 Practice for Ultimate Analysis of Coal and Coke
D3180 Practice for Calculating Coal and Coke Analyses from As-Determined to Different Bases
D3302 Test Method for Total Moisture in Coal
D5192 Practice for Collection of Coal Samples from Core
E1272 Specification for Laboratory Glass Graduated Cylinders
AS3980 Guide to the determination of gas content of coal--Direct desorption method Available from Standards Australia Limited, 286 Sussex St., Sydney, NSW, 2000, Australia, GPO Box 476, Sydney, NSW, 2001 Australia or via the website: www.standards.org.au.
DIN12681 Plastics laboratory ware--Graduated measuring cylinders Available from Deutsches Institut fr Normung e. V., 10772 Berlin or via the website: http://www2.din.de.
coal bed; coal gas; core; desorption; gas content; gas sampling; gas volume measurement; methane; resource assessment;
ICS Number Code 73.040 (Coals)
ASTM International is a member of CrossRef.
Citing ASTM Standards
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