Numerical simulation of KGD hydraulic fracture based on PPCZ model

Based on Barenblatt’s cohesive zone model,the pore pressure cohesive zone model takes into account on the effect of fracture process zone,which has some advantages for simulating the hydraulic fracture propagation. This model was used to study the KGD hydraulic fracturing problem. Its capability of simulating the KGD hydraulic fracture was verified. The influence of fracture process zone and fluid viscosity μ on the fracture propagation was analyzed. The rela-tionship between fluid displacement Q0 ,fluid viscosity μ and injection time was revealed. Research shows that ① the fracture process zone has an impact on the fracturing result. As the crack stiffness Knn changes,the fluid penetrates to fracture process zone to different extents,which changes the ease of fracture and the response of fluid pressure within the fracture. ② An increase in fluid viscosity results in an increase in net pressure and crack width,but a decrease in crack length. ③ The final geometry of hydraulic fracture will not change in μQ0 unchanged,and Q0 t unchanged condi-tions. ④ Compared with the elastic state,the elastoplastic state of the rock requires a higher net pressure to initiate and propagate. Pore pressure cohesive zone model has the ability to simulate different types of hydraulic fractures. Conclu-sions can be further developed for practical engineering applications.