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

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.Resultsshow 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.