Impact of coal reservoir physical property on coalbed methane desorption and production

The factors influencing coalbed methane(CBM) desorption and production act on coal reservoir,and are reflected as the ability of reservoir allowing CBM to diffuse and permeate.So the coal reservoir physical property should be paid more attention when doing research on gas desorption.For this reason,the physical property differences between high and low rank coal reservoirs were studied,and the impact of physical property differences on gas desorption and production were discussed.The results show that the molecular structure of low rank coal is loose,and the porosity is high.However,the molecular structure of high rank coal is tight,and the porosity is low.The physical property of low rank coal is better,whereas,that of high rank coal is worse during gas desorption.Both canister desorption of coal and simulation experiment imply that reservoir physical property is the key element of influencing gas desorption,which is also the underlying reason of low rank coal's high development potential despite low gas content.The low rank coal has better porosity and permeability,and in which the pressure spreads fast,so self-relieving pressure effect can be formed easily during exploitation.The high rank coal has poor porosity and permeability,and in which the pressure spreads slowly,so massive fracturing and multilateral well technique should be adopted in order to increase single well yield.