煤成气有煤系气和煤层瓦斯两种,各有其化学组成及甲烷碳同位素特征。煤层瓦斯因与CO_2之间的碳同位素交换或因生物作用而富含~(12)C。煤系气主要来自煤系中分散的有机质,较瓦斯富含~(13)C。甲烷碳同位素的研究对煤成气的分类、成因及资源评价均有重要意义。 There are two kinds of coal-bearing gas and coal seam gas coal gas, each with its chemical composition and carbon isotope characteristics of methane. Coal seam gas and carbon dioxide between the carbon isotope exchange or biological role because of rich ~ (12) C. Coal-based gas is mainly derived from organic matter dispersed in the coal system, which is more abundant than methane (13) C. The research of methane carbon isotopes is of great significance to the classification, genesis and resource evaluation of coal-formed gas.