Influence of fracturing pressure of vertical well to CBM capacity in Jiulishan coal mine

Based on the elastic plane strain theory, this article deduces the crack pressure calculation formula of fracturing extraction wells under different geological constructions in order to summarize the successes and the failures of the fracturing extraction experiment in the Jiulishan coal mine of the Jiaozuo coal field. By comparing the computation results with the actual drainage test data, it is found that in the tensile fracture development areas, the overlarge fracture measures will do great harm to the impermeable bases of coal reservoirs near the coal bed gas wells, and the fracturing fractures spread to the L7-8 karst aquifer of the Taiyuan Group, resulting in a large number of underground water into the surface wells. The fierce river course of groundwater makes almost all the coal bed gas escape from the interspaces of the reservoir stratums where it stays. Additional water pressure makes it difficult for much coal bed gas absorbed in fissures to escape, so it cannot form a long-term stable single well scale output.