Experimental study of the effect of natural fracture curvature on hydraulic fracture propagation behavior

Abstract

The interaction mechanism between hydraulic fractures and natural fractures has been the focus of hydraulic fracturing research. To reveal the influence mechanism of natural fractures with different curvatures on hydraulic fracture propagation during the fracturing process, this study simulated the hydraulic fracture propagation patterns under natural fractures with different curvatures by carrying out large-size true triaxial hydraulic fracturing physical modeling experiments on artificial rock samples prefabricated with different curvatures of fractures. Results show that the injection rate of fracturing fluid and the curvature of natural fractures have important effects on the interaction between hydraulic fractures and natural fractures. When the approximation angle (the angle between the hydraulic fracture and the natural fracture) is 90°, with the gradual decrease of the fracturing fluid injection rate, the interaction between the hydraulic fracture and the natural fracture shows that the hydraulic fracture passes through the natural fracture directly, and gradually changes to the hydraulic fracture passes through the natural fracture and also extends along the natural fracture, and then in the end, only hydraulic fracture extends along the natural fracture occurs. When the injection rate is constant and the approximation angle is 90°, with the curvature of the natural crack gradually increasing (increasing curvature), the interaction between the hydraulic fracture and the natural fracture shows that the hydraulic fracture passes through the natural fracture and also partially extends along the natural fracture, and gradually changes to the hydraulic fracture extending only along the natural fracture, and then finally extends along the direction of the maximum horizontal principal stress. The results of the study are instructive for revealing the interaction mechanism between hydraulic fractures and natural cracks.