Research on hydraulic fracturing gas extraction technology for No.15 coal seam of Wulihou Coal Mine

Aiming at the problems existing in conventional pre-extraction holes in No.15 coal seam with low permeability of Wulihou Coal Mine, such as intensive drilling, high cost, low extraction efficiency and long extraction period, etc., the research on hydraulic fracturing gas extraction technology of drilling along the layer was carried out. The field test results show that the maximum principal stress of 2101 working face is horizontal stress, the stress value is 18.3 MPa, and the direction angle is N31.65°E, and the middle principal stress is the vertical stress. The fracture generated is along the maximum principal stress direction, and the fracture morphology is dominated by the vertical fracture position. The fracture initiation pressure of coal seam is about 25 MPa to 29 MPa, and the fracturing influence radius is about 5 m to 8 m. Four months after fracturing, the cumulative amount of gas extracted is about 1.8×10⁴ m³, and the gas content per ton of coal decreases from the original 10.85 m³/t to 2.63 m³/t, indicating a significant effect of fracturing and extraction. The drilling quantity is reduced by half, the gas extraction period is shortened by 2 months to 3 months, and the economic benefit of coal mine is significantly improved after fracturing extraction technology is adopted. It also has important reference significance for the rapid tunneling construction of driving face.