Application and Research on Seam Hydraulic Fracture Permeability Improvement Technology

In order to solve the gas concentration frequently exceeds the limit in the return airway of the 2264-1N-S working face of TanJiaChong coal mine,the hyd raulic fracture permeability improvement technology was proposed to improve the gas drainage rate,aiming at reducing the risk of coal and gas outbursing and increasin g the permeability.Based on the analysis of the hoop stress around the hole and the maximum tensile stress theory,the critical water pressure of crack initiation was 15. 7 MPa through calculation.When the site test was done by using the developed hydraulic fracture equipment,the results showed that the gas extraction flowrate and con centration of the single bore were significantly improved and the attenuation coefficient of gas flowrate was low.