煤层甲烷解吸—扩散—渗流过程的影响因素分析

Analysis of the factors affecting processes of CBM desorption,diffusion and percolation

从煤层甲烷产出机理入手 ,分析了影响煤层甲烷解吸、扩散和渗流过程的因素。结果表明 :影响解吸的因素主要是压力、含气量、煤的水分含量、基块尺寸、温度等 ;影响甲烷扩散的因素主要是甲烷浓度、扩散距离、平均自由程和煤岩孔隙分布 ;而影响渗流的因素有渗透率、裂隙发育状况、压差、储层损害等。进而指出 ,解吸、扩散和渗流 3个环节紧密相连 ,相互影响 ,相互制约 ,三者的最佳匹配将是煤层气经济开发的必要条件。

Starting with the mechanism of CBM production,this paper analyzes the factors that affect the processes of coalbed methane desorption,diffusion and percolation from coal seams.Results show that the main factors influencing methane desorption include pressure,gas content,coaly moisture content,matrices size and temperature etc.;the factors influencing methane diffusion mainly include methane concentration,diffusion distance,mean free path and pore distribution in coal seams;whereas the main factors influencing methane percolation include permeability,status of fracture growth,pressure difference and formation damage etc.Furthermore,it is pointed out that desorption,diffusion and percolation of CBM from coal seams are three inseparable processes interacted each other.Their optimum matching will be a necessary condition for economic development of coalbed methane.