The characteristics and controlling factors of coalbed methane reservoir in the North Qinshui Basin

Based on the data obtained from the exploration for coal and coalbed methane, the characteristics of coalbed methane reservoir in the North Qinshui Basin is discussed systematically. The description on the reservoir property (including coalbed geometry, gas content, adsorption, physical property of the coal, reservoir pressure etc.) and controlling factors (including the structure, sealing condition, Hydrogeological condition, and karst collapse column) of the coalbed methane reservoir show that coalbed methane accumulation of research area is the result of reasonable effective disposition of geologic feature and geological processes controlled by extrinsic geological action processes. Gas saturation overall low is mainly caused by the bearing strata after uplift re-subsidence; the coalbed methane accumulation is controlled by the structure, the roof and floor of coal sealing condition; the groundwater stagnant zone is the favorable area for coalbed methane accumulation; and karst collapse columns and partial opening faults are major factors for coalbed methane leading to depletion.