Application of repeated hydraulic fracturing technology in Baoan coal mine

In order to improve the permeability of coal reservoir and reduce the blind zone of hydraulic fracturing, this paper puts forward the technology of underground mine repeated hydraulic fracturing to enhance permeability, and expounds the general process flow of underground mine hydraulic fracturing.According to the characteristics of geology and coal seam in Baoan coal mine, the key technical parameters of repeated hydraulic fracturing are designed, and repeated hydraulic fracturing test and fracturing effect test are carried out.The results show that the recovery of pure quantity and extraction concentration averaged 0.0024 m³/min and 6.2% pumping without fracturing area of single hole gas fracturing, the regional average was 0.0051m³/min and 11.2%, up to 1.125 times and 0.81 times respectively, significantly enhance the recovery effect of gas drainage; without fracturing coal permeability coefficient is 0.007861 m²/(MPa²·d), after fracturing 0.317582 m²/(MPa²·d), increases more than 40 times; hydraulic fracturing after 100 meters flow attenuation coefficient from the original coal flow attenuation coefficient of 0.024 meters reduced to 0.021, reduces by 12.5%.The test results show that the repeated hydraulic fracturing can effectively improve the underground gas drainage effect, and have the popularization and application value in the coal mine gas disaster prevention and control.