关键词: 高瓦斯低渗透煤层, 瓦斯抽采, 卸压增透, 数值模拟

Abstract: Aiming at the engineering problems of low gas pre-drainage efficiency，fast attenuation and long pre-drainage cycle caused by high gas and low permeability characteristics of 3# coal seam in Zha⁃ ozhuang Coal Mine，the hydraulic punching pressure relief and permeability enhancement technology is used to carry out gas control optimization research. Based on COMSOL Multiphysics，a gas radial seepage model is constructed to analyze the influence of different coal-flushing amounts on the extraction radius. The results show that the coal-flushing amount is significantly positively correlated with the effective extrac⁃ tion radius，and the maximum effective extraction radius in 90 days extraction cycle can reach 5.0 m. Com⁃ bined with FLAC3D numerical simulation，the pressure relief effect of surrounding rock with different com⁃ binations of coal washing amount and hole spacing is compared and analyzed. Considering the safety and economy of the project，the optimal construction parameters of 1.5 t/m coal washing amount and 7 m hole spacing are selected. The field industrial test shows that the gas extraction concentration of hydraulic punching borehole is stable at more than 30%，without obvious attenuation，and the pure amount of gas ex⁃ traction is stable at more than 0.05 m3 /min. The average daily extraction rate of single borehole in the test borehole is 12.8 m3 /d，which is about 2 times higher than that of ordinary borehole. This technology can ef⁃ fectively improve the fracture development conditions of low permeability coal seams and significantly im⁃ prove the gas extraction effect，which can provide reference for gas control in similar mines.

Key words: high gas and low permeability coal seam, gas extraction, forced pressure relief antireflec? tion, numerical simulation