Enhancing fracture uniformity in hydraulic fracturing: A 3D simulation study on natural fracture networks and plugging optimization

ABSTRACT The non-uniform propagation of multi-cluster fractures during the hydraulic fracturing of deep shale gas reservoirs is an ongoing challenge. The dynamic interaction between natural fracture networks and in-situ stress fields strongly affects fracture propagation, decreasing fracturing efficiency. In this study, a 3D discrete lattice numerical simulation is employed to systematically analyze the dynamic regulatory mechanisms of multi-cluster fracture propagation under the combined effects of natural fracture characteristics, differential in-situ stress, and temporary plugging strategies. The goal is to optimize temporary plugging parameters for balanced fracture extension. The results reveal that increasing the natural fracture density and size reduces the average hydraulic fracture length while markedly mitigating stress shadowing effects. A greater difference in horizontal in-situ stress intensifies the inter-fracture stress, suppresses natural fracture activation and decreases mechanical interference. Ball-sealing temporary plugging effectively limits the excessive growth of dominant outer fractures. As the number of plugging balls increases, the fracture length differentiation coefficient decreases but then increases, with the optimal plugging timing identified at 37.5% of the total fracturing duration. Single-stage plugging achieves a better fracture length differentiation coefficient than two-stage plugging does. Field applications require multi-stage plugging to increase operational tolerance, which requires proportional increases in the number of plugging balls. The established optimization criteria for temporary plugging parameters provide a theoretical basis for increasing the development efficiency of deep shale gas reservoirs.