Fracture network characterization of high-rank coal and its control mechanism on reservoir permeability

Based on the results of previous research fracture systems reservoirs middle- and low-rank coal, we took high-rank coal in southern Qinshui Basin as study object this paper summarize characteristics both macro- micro-fractures different rank coals, establish a geometric model network for explore mechanism reservoir permeability change under conditions. The found that structure developed unevenly. had rift created outside, micro-fracture development, undeveloped endogenous fracture, which can be used to improve reservoir, certain extent. We concluded given absence seepage aisle there is rapid increase from low high rate during process network. However, other increases smoothly. Due compression matrix shrinkage, first decreases then drainage stage. At same pressure drop, at fastest rate, followed by middle-rank order.