Study On Propagation Behavior Of Hydraulic Fractures In Rock Mass Based On Structural Surface

Hydraulic fracturing technology is widely used in oil and gas exploitation.With the exhaustion of conventional oil and gas resources,unconventional oil and gas resources play an increasingly prominent role in the field of energy.Therefore,the development of unconventional oil and gas resources in China is urgent.This paper mainly adopts computer simulation method and takes a current research hotspot,the shale rock mass as the object.The initiation and expansion phenomena is systematically researched under three conditions below: rock with single natural fracture;rock with two natural fractures;rock with a natural fracture and a hydraulic fracturing inside the rock caused by joint.The simulation results are compared with the physical experiment results of the literature,which has verified that the numerical simulation results is credible in some degree.With initiation pressure,the difficulty of rock failure is analyzed when the rock encounters different angles between the natural crack and the maximum principal stress.According to the pore water pressure cloud imagery and the minimum principal stress chart,the trend of the hydraulic crack is described and the stress state when the crack tip cracks is analyzed.By containing a single fracture,two orthogonal fractures,joint and fissure orthogonal three shale under hydraulic fracturing of rock mass under the condition of the present phenomenon is analyzed and summarized,found that these three conditions on the crack hydraulic crack and extend the effects are only temporary,eventually crack extension direction will tend to be more consistent with the maximum horizontal principal stress direction.With the aid of numerical simulation and physical experiment result contrast method,the experimental phenomena can be better simulated by the system of rock fracture process analysis(RFPA).Based on the simulation of single crack,single crack and joint intersection in rock sample,the formation condition of complex fracture network in rock mass with structural plane is obtained.Combined with the minimum principal stress diagram of each model,it can be found that the model is under the stress state of confining pressure and hydraulic pressure,and the propagation of hydraulic crack and the failure of the model are caused by tensile stress during the loading process.