[Geostress-Driven Fracture Evolution in Shale: An XFEM Study on Injection Direction, Cluster Spacing, and Reservoir Response]

Hydraulic fracturing is crucial for shale reservoir development. This paper uses the extended finite element method (XFEM) to model hydraulic fracturing, incorporating real horizontal geostress fields in shale. We investigate how horizontal well injection direction (single-cluster fracturing) and cluster spacing (double-cluster fracturing) impact fracture extension.Results show that due to significant stress differences, hydraulic fractures consistently turn towards the maximum horizontal principal stress, except when the injection angle (α) is 0°. The turning radius increases with α (15°, 30°, 45°, 60°). Additionally, fracture pressure positively correlates with the injection angle, though all rupture pressures in this study are high due to reservoir properties.Under double-cluster fracturing, cluster spacing strongly influences fracture morphology. Small spacings (2m, 5m) lead to significant mutual influence between fractures, which diminishes as spacing increases. Beyond 11m, there's virtually no recognizable influence between the two hydraulic fractures. This research offers valuable insights for efficient shale gas development.