Numerical simulation on crack propagation of hydraulic fracturing process under different in-situ stress

To investigate the failure mechanism of the rock fracture initiation, propagation under the action of coupled stress-seepage, this study simulates the propagation of hydraulic fracturing crack under different stress level and different initial angle cracks using the RFPA2D-Flow program. Study results show that with the gradual reduction of confining pressure level from 80 MPa to 45 MPa, under the water pressure, the formation of the straight crack perpendicular to the direction A gradually deviates from the direction A, at the same time, a lot of random cracks are developed around the tortuous path. In the prefabricated cracks of hydraulic fracturing, the water pressure penetrates through the prefabricated crack. The study provides a theoretical foundation and scientific basis for the oil industry to improve oil extraction rate.