Propagation behavior of hydraulic fracture across the coal-rock interface under different interfacial friction coefficients and a new prediction model

Indirect fracturing from rocks to coal is a promising technology of coalbed methane exploitation in soft and low-permeability coal seams. Central to this technology is the prediction of the propagation path of the fluid-driven fractures at the coal-rock interfaces, which requires a deep understanding of the role of the friction properties of coal-rock interfaces. In this paper, we performed hydraulic fracturing experiments using coal-rock blocks...