Coal Reservoir Permeability in the Gemudi Syncline in Western Guizhou, China

Coal reservoir permeability is an important parameter to used to evaluate coalbed methane resource potential and select favorable zones. This article presents a research on Gemudi syncline. The coal reservoir permeability was largely studied by a considerable amount of geological data obtained from mercury injection experiments, scanning electron microscope observation, and gas/water phase permeability tests. The results revealed that the macro-fractures are especially developed in Gemudi syncline. The micro-fractures and micro-pores of Gemudi syncline are also well developed. The pores, of which the diameters are less than 0.10 m, occupy the biggest proportion, above 70%. Most pores are open. The measured permeability of the samples varies from 0.33 to 6.69 mD, although most are higher than 0.5 mD. Considering the Mopan mountain mine, which has similar conditions with Gemudi syncline, it is thought that the permeability of coal seams in Gemudi syncline is comparatively high. But the large amount of micropores in this region, which have strong adsorption, may cause coalbed methane desorption difficulty when exploiting.