High efficiency gas extraction technology of directional drilling hydraulic fracturing in stratified tectonic coal seams

In order to achieve high-efficiency gas drainage in stratified tectonic coal seams, this paper takes Yushutian Coal Mine as the test point to carry out the research on high-efficiency gas drainage technology of directional drilling hydraulic fracturing in stratified tectonic coal seams. According to the stratified tectonic characteristics of the lower 5# coal seam in Yushutian Coal Mine, the second cycle gas drainage and fracturing boreholes of 110503 transportation roadway are arranged in the semi dark briquette stratification. A total of 5 bedding boreholes are constructed, the cumulative drilling length is 3 000 m, the drilling direction control range is 600 m, and the inclination control range is 15 m outside the contour lines of the upper and lower sides of the roadway; the cumulative fracturing length of the borehole is about 2 500 m, the cumulative liquid injection volume is 570 m3, the fracture initiation pressure of each hole section is 7.6-8.8 MPa, and the maximum pump injection pressure is 11.9-13.8 MPa. The research results show that compared with the first cycle directional fracturing borehole in 110503 transportation roadway without considering the stratified tectonic in the semi bright briquette layer at 1/2 of the coal thickness, the second cycle directional fracturing borehole is arranged in the semi dark briquette layer, the monthly average gas drainage concentration of the drilling yard is increased by 4.3 times, and the monthly average gas drainage purity is increased by 3.2 times.