根据常压下的解吸实验和煤层气参数井实测数据分析 ,我国煤的解吸特性变化较大 ,解吸率主要受煤层埋深及煤级的影响。最佳解吸深度一般在 40 0～ 60 0 m之间 ,镜质体反射率小于3%时 ,随煤级的升高而增大 ;大于 3%时 ,则相反。我国煤储层的吸附时间长短与煤级没有特定关系 ,但在某些地区与煤层的含气量高低有关 ,甲烷含量低则吸附时间长 ,尤其是小于 8m3 /t时急剧增长。从现有资料看 ,我国煤储层的吸附时间一般不超达 9d。煤层甲烷采收率不仅取决于煤层的含气性、煤的吸附—解吸特性以及煤层所处的原始压力系统 ,而且还受控于钻井技术及开采工艺。根据美国的经验和我国部分测试结果 ,估算我国煤层甲烷的平均理论采收率为 2 7% According to the desorption experiment under atmospheric pressure and the measured data of coalbed methane parameter well, the desorption characteristics of coal in our country vary greatly. The desorption rate is mainly affected by the depth of coal seam and the coal grade. The optimal depth of desorption is generally between 40 0 ​​~ 60 0 m, and when vitrinite reflectance is less than 3%, it increases with the increase of coal rank; The adsorption time of coal reservoirs in China is not related to the coal rank, but it is related to the gas content of coal seams in some areas. The low methane content results in long adsorption time, especially less than 8m3 / t. Judging from available data, the adsorption time of coal reservoirs in our country generally does not exceed 9 days. Coal seam methane recovery depends not only on the gas content of the coal seam, on the adsorption-desorption characteristics of the coal and on the original pressure system in which the coal seam is located, but also on the drilling and mining processes. According to the experience of the United States and some of the test results in China, it is estimated that the average theoretical recovery rate of coalbed methane in China is 27%