Study on the influence of physical parameters of coal and rock on hydraulic fracture propagation law

Hydraulic fracturing technology plays an important role in the field of coalbed methane exploration, but the influence of physical parameters of coal seam on hydraulic fracture propagation law is still unclear. In this paper, the initiation time, initiation pressure and fracture propagation law under different mechanical parameters and dip angles of coal seams are studied by RFPA2d-Flow numerical simulation software. The results show that: (1) The direction of fracture propagation is mainly perpendicular to minimum principal stress. (2) The smaller the elastic modulus of coal seam, the easier it is to form hydraulic fractures with wider width. The higher the compressive cracking resistance of coal seam, the later the initiation time. (3) The greater the compressive strength, the greater the initiation pressure, the longer the initiation time, the shorter the fracture length and the narrower the fracture width. Compared with elastic modulus, compressive strength has more significant influence on hydraulic fracture propagation in coal seam. (4) Under the same dip angle, the initiation pressure and cracking pressure of hard coal are bigger than those of soft coal. The research results can provide theoretical basis for coalbed methane exploration and hydraulic fracturing technology research.