煤层气含量的测定方法

[中文适用范围]： 本国际标准规定了测量煤核样品中煤层甲烷含量的方法，这些样品是在钻探过程中通过取心或侧壁取心获得的。如果无法根据相应的国家标准确定煤层甲烷含量，则也适用于对岩屑样品进行分析。选择最合适的方法应考虑测试目的和取样可能性。本国际标准适用于直接测量煤层甲烷含量的方法。其中包括样品制备、实验程序和计算方法。间接测量煤中气体含量的方法（未包含在本国际标准中）通常基于在规定/指定的压力和温度条件下，煤的气体吸附特性。本国际标准包括三种直接测量方法：常规脱气（慢速脱气）法、快速脱气法以及快速测定岩屑或块状样品中的甲烷含量。它们之间的区别在于允许气体在最终破碎前脱出的时间、样品大小和形状。本国际标准适用于煤炭和煤层甲烷勘探中确定甲烷含量。低阶煤的游离气含量测定包括在内，但需明确测定步骤。本国际标准中使用的单位和涉及的所有单位均为国际标准单位。参考温度为0 °C（273.15 K），除非另有说明。参考压力为0.1 MPa（1 bar），除非另有说明。本国际标准并未指明所有与使用有关的潜在安全危害。用户在应用本标准中定义的程序时，需自行建立适当的安全措施和健康规范。 [外文原描述]： ISO 18871:2015 provides methodology for measuring coalbed methane content of coal core samples obtained by coring or sidewall coring during well drilling. It shall be also applied to drill cuttings samples, if the equipment for the determination of the coalbed methane content according to a respective national standard is not available. The selection of the most appropriate method shall consider the purpose of the test and the possibilities of sampling. ISO 18871:2015 is applicable for the direct method of measuring coalbed methane content. It includes sample preparation, experimental procedures and calculation methods. Indirect methods of measuring gas content of coal (not included in this standard) are generally based on either the gas sorption characteristics of coal under defined/specified pressure and temperature conditions. ISO 18871:2015 includes three types of direct measuring methods: conventional desorption (slow desorption) of core samples, fast desorption of core samples, fast desorption of cuttings or lump samples. The difference among them lies in the time allowed for gas to desorb before final crushing and in sample size and shape. ISO 18871:2015 is applicable for the determination of the methane content of coal during coal and coalbed methane exploration for the determination of free gas content of low rank coals is included.