Coupled XFEM–Fluid Pipe Element Modeling of Nonuniform Fracture Propagation in Multicluster Fracturing: A Case Study of the Shaximiao Formation, Zitong Area in China

Abstract

This study investigates the challenge of imbalanced fracture propagation during multicluster hydraulic fracturing in tight sandstone reservoirs of the Zitong Shaximiao Formation. A coupled extended finite-element method (XFEM)–fluid pipe element model is developed to systematically analyze the influence of operational parameters on fracture behavior. Numerical simulations show that increasing the injection rate to 18.0    m 3 / min reduces fracture length imbalance by 21.8%, improves the equilibrium coefficient from 0.62 to 0.79, and lowers energy consumption per unit fracture length by 47% compared to a 20    m 3 / min scheme. Although a five-cluster configuration reduces maximum fracture length by 34%, it achieves optimal total fracture length when combined with 20 m cluster spacing under a geostress difference of 16.6 MPa. An innovative heterogeneous initiation model incorporating wellbore deviation and azimuth quantifies the effect of diverting agents in regulating fluid distribution, reducing outer cluster intake by 24.3%. Field application of the developed stimulated reservoir area (SRA) real-time evaluation module in Well A5 at 3,910 m depth (initiation pressure: 64.11 MPa) successfully identifies preferential fracturing intervals, increasing single-well production by 22%. These results provide theoretical insights and practical strategies for enhancing recovery in tight gas reservoirs under complex geological conditions.