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在系统总结我国煤层甲烷稳定碳同位素的地域、时域和煤级分布特征的基础上，对其成因进行了探讨，研究表明：我国煤层气稳定碳同位素具有分布范围广、同位素组成偏轻的总体特点，在进入无烟煤阶段之后煤层甲烷δ13C1开始接近或落入腐殖型常规天然气甲烷稳定同位素分布范畴，煤层一次脱气的δ13C1轻于二次脱气；我国大部分地区中－高煤级煤储层中现存煤层气碳同位素分布主要受控于热动力学机制之下的同位素分异，解吸－扩散－运移分馏效应在此背景之上的叠加，可能是导致煤层甲烷碳同位素偏轻的主要原因。
Based on the systematical summary of the regional, temporal and coal-level distribution characteristics of the stable carbon isotopes of methane in coal seams in our country, the causes are discussed. The results show that the stable carbon isotopes of coalbed methane in our country have a wide range of distribution and light isotope composition After entering the stage of anthracite, the δ13C1 of coal seam began to approach or fall into the stable isotope distribution of methane in conventional humus gas. The primary degassing of δ13C1 in the coal seam was lighter than the secondary degassing. In most areas of China, medium- The distribution of carbon isotope in the existing CBM is mainly controlled by the isotopic differentiation under the thermodynamic mechanism. The superimposition of desorption-diffusion-migration fractionation above this background may be the main reason for the light carbon isotope of methane in the coal seam the reason.