Turbulence effect of high-speed fracturing fluid in hydraulic fracturing main fracture of hard roof rock

Taking 31103 working face of Bayan Gaole Coal Mine in Inner Mongolia as the research background, the theoretical analysis methods of fracture mechanics, material mechanics and rock mechanics are adopted, and the experimental scheme is designed with numerical simulation software.The reasonable construction process parameters of hydraulic fracturing, pressure relief and impact prevention covered with 10 m thick hard roof plate on 31103 working face are studied based on the field measured fracturing effect.Firstly, the mechanical model of main fracture initiation and propagation in fractured rock stratum driven by high-pressure water flow is established, and the relationship between the critical water pressure of hydraulic fracturing fracture initiation and the geometric size of extended fracture under actual conditions is obtained.Secondly, according to the calculation convergence results of Comsol fluid solid coupling simulation experimental software on the hole wall surface pressure and fracture propagation boundary conditions caused by the flow of high-pressure water in the borehole and fracture, it can be seen that the interaction between the flow state of fracturing fluid and the surface tension of rock borehole and fracture in the construction process of hole sealing, water injection, pressure holding until the sudden drop of fracture penetration water pressure.Finally, considering the data information fed back from the on-site construction, the reasonable hydraulic fracturing construction process parameters suitable for the thick and hard roof of 31103 working face of Bayan Gaole Coal Mine are finally determined.