Simulating a High-Resolution Tectonic Stress Field and Predicting the Fracture Distributions in Shale Reservoirs Based on a Heterogeneous Rock Mechanics Model with Adaptive Boundary Condition Constraints

Obtaining higher-resolution and more realistic characteristics of tectonic stress fields is the goal of research into tectonic stress field simulations. In this study, a regional heterogeneous rock mechanics model was established on the basis of seismic, logging, and sample experimental data. The simulation results show that the minimum principal stress values in the lower Niutitang formation are between 25.0 and 120.0 MPa. The quantitative distribution prediction results for shale reservoir fractures based on the high-resolution tectonic stress field numerical model show that the fracture development zones in the Sangzhi block are mainly distributed near the fault, fold axis turning, and fold wing in an NE–SW orientation. There are two types of fractures developed in this region: shear fractures and tensile fractures. The shear fractures mainly developed near the NE–SW-oriented faults, with shear fracture rates ranging from 1 to 3, and the tensile fractures mainly developed in the southeast wing of the Wudaoshui anticline, with tensile fracture rates ranging from 1 to 2. The low fracture development zone is mainly located in the western slope of the block, with shear fracture rates and tensile fracture rates that are both < 1.