Numerical simulation study on permeability and humectant properties of coal seam water injection under high water pressure in long drilling hole

Based on ANSYS numerical simulation method, the 50 m and 80 m drilling length of the coal seam water injection physical model are established, the numerical simulation study of coal seam water seepage pressure, velocity field variation and water wetting distribution is conducted under injection pressure of 20 MPa. The results show that permeability and humectant properties concentrate within the drilling hole and decrease on both sides to a certain gradient. Meanwhile, the 80 m long drilling coal seam water injection pressure and moist coal distribution range increase, the minimum of moisture increment value reaches 1.2%, higher than the 50 m drilling layout. The sealing section of longer drilling hole does not appear the pressure distribution, which helps to prevent the leakage of water injection. The results show that longer drilling of the coal seam under high pressure water can achieve better effect, which provide a basis for optimizing the design of water injection parameters.