Multi-fracture propagation and proppant transport analysis based on a non-planar three-dimensional fracturing model

An integrated non-planar three-dimensional (3D) fracture propagation and proppant transport model is developed, capable of simulating key physical behaviors in heterogeneous in situ stress fields, including fracture propagation, deflection, intersection, coalescence, and proppant transport, settling, and bridging. After validating the model reliability with true triaxial hydraulic fracturing laboratory experiments and numerical simulations of non-planar fracture propagation, the proposed model is employed to analyze the impact of in situ stress field heterogeneity on fracture initiation and propagation pressures, non-planar propagation paths, fracture width, and proppant concentration distribution. The simulation results indicate that the principal stress orientation determines the final propagation direction of hydraulic fractures, while the horizontal stress difference affects the curving length required for non-planar fracture reorientation. Stress interactions induced by multi-fracture propagations not only lead to uneven growth but also non-planar geometries, as hydraulic fractures preferentially propagate along the paths of minimal energy dissipation. Proppant distribution is primarily governed by fracture geometry and width, with proppant concentrated near the wellbore where fracture width is greater. Deflected in situ stress fields promote non-planar fracture propagation, as well as intersection and merging, with larger stress deviation angles accelerating fracture deflection and coalescence. The sudden width variations and slurry convergence at fracture intersecting points significantly raise proppant concentration, potentially leading to premature proppant screen-out. Inter-cluster stress heterogeneity affects the simultaneous initiation and propagation of multiple fractures, while inter-well stress heterogeneity induces asymmetric fracture geometries and proppant concentration distribution. In multi-well pad fracturing, the evolution of 3D pressure and stress fields caused by production or injection from parent wells can strongly influence the preferential growth paths of fractures in new wells.