Three-Dimensional Numerical and Theoretical Analysis of Stress-Shadow-Induced Reorientation of Echelon Hydraulic Fractures in Dual-Well Stimulation

Multistage hydraulic fracturing enhances recovery from low-permeability reservoirs. Understanding stress shadow effects and fracture reorientation is essential for optimizing multistage fracturing. This study develops a fully coupled 3D hydromechanical model based on the finite–discrete element method (FDEM) to simulate echelon hydraulic fractures in dual-well systems under varying well spacings and initial perforation lengths. Results show that fracture interactions are highly sensitive to spacing and initiation asymmetry. Closely spaced fractures generate strong stress shadows, influencing propagation depending on geometry and timing. A theoretical model incorporating induced stress and the weight function further clarifies stress shadow mechanisms, introducing disturbance factors to describe promotion or inhibition effects between fractures. The findings reveal an optimal well spacing that maximizes fracture complexity and reservoir stimulation, while pronounced initiation asymmetry leads to dominant–subordinate propagation and reduced efficiency. This integrated framework improves understanding of fracture evolution and guides fracturing optimization in tight formations.