Influence of Control Holes in Coal Seam on Fracture Propagation Under Hydraulic Fracturing

The pressure relief of coal seam is the effective measure to reduce pressure. In order to improve the effect of pressure relief, the fluid-solid coupling model was established by using RFPA^3D parallel analysis system and the finite element calculation method. The fracture propagation process induced by four direction control holes is simulated and analyzed under constant water pressure. The results show that, because of the role of the maximum principal stress, the new fracture eventually expands towards the control hole direction under constant water pressure, finally connects with the control hole, which plays a certain permeability increasing role to reduce the stress of coal seam.