Discrimination Model of Interaction Between Hydraulic Fracture and Natural Fracture Based on Energy Balance

Hydraulic fracturing technology has been extensively applied for the efficient development of unconventional reservoirs. Influenced by geological discontinuities such as naturally fractured weak planes, the complex interaction behaviors between hydraulic fractures and natural fractures significantly challenge the prediction of hydraulic fracture propagation paths. Establishing interaction discrimination models to predict these behaviors proves crucial for characterizing post-stimulation fracture complexity. This study develops a discrimination model for hydraulic-natural fracture interactions based on fracture mechanics theory and energy balance principles. The critical conditions of hydraulic fracture crossing, natural fracture opening, and slippage are quantified, and the interaction propagation behavior of hydraulic fracture and natural fracture under different geological parameters is analyzed. Key findings reveal three interaction modes after fracture intersection: direct hydraulic fracture crossing, natural fracture opening, and natural fracture slippage. However, continuous fluid injection-induced pressure buildup within fractures ultimately drives hydraulic fracture crossing through natural fractures. Threshold effects emerge at specific hydraulic fracture lengths (0.5 m) and fracture toughness values (2 MPa·m0.5), governing the transition between direct crossing and natural fracture opening behaviors. Horizontal stress difference directly modulates the threshold values of natural fracture cohesion, friction coefficient, and approach angle. These three parameters collectively control the temporal sequence of hydraulic fracture crossing behaviors through natural fractures. The interaction discrimination model established in this study provides theoretical guidance for optimizing fracturing parameter design in fractured reservoirs.