Productivity prediction of hypotonic CBM test well in Jiaozuo mining area under hydraulic fracturing

In order to explore the permeable mechanism and the output law after fracturing of CBM in the "three soft" coal seam(soft coal, soft roof and soft bottom) of Jiaozuo under hydraulic fracturing, Based on the permeable model of reservoir fracture, considering the influence of fracture porosity on permeability after fracturing, a reservoir fracture penetration model was established, the application and analysis of the test well was carried out to obtain the characteristics of pressure cracks such as length, width, permeability and reservoir parameters after fracturing. Through the comprehensive analysis of isothermal adsorption curves and historical fitting, the recovery rate of CBM was predicted, finally, combined with the obtained index parameters and recovery rate, the production of test well GW-002 in the mining area was predicted by Fracpro PT software for 2 430 d. The results show the average daily gas production is 596.87 m³/d, the recovery rate is 32.86% and the cumulative gas production is 1.09×10⁶ m³, the gas production from the software is in good agreement with the actual production data, which meets the technical requirements of CBM and could be used to guide the fracturing drainage practice and production capacity in Jiaozuo mining area.