Research on Production Improvement with Coupled 3D Geological and Geomechanics Modeling for Well Spacing Optimization

Abstract The Upper Xiaganchaigou Formation (E32) in Qaidam Basin represents a key shale oil target in China. Guided by the development principle "vertical wells for resource delineation, horizontal wells for production enhancement," seven vertical wells across ten intervals achieved commercial flow during completion testing. The dedicated appraisal well CP1 demonstrated breakthrough potential at Yingxiongling with 124.3 m3/d oil and 15,358 m3/d gas production through a 4-mm choke at 31.8 MPa flowing pressure, confirming significant shale oil producibility. However, Yingxiongling shale oil faces significant challenges including exceptionally thick reservoirs, strong heterogeneity, and suboptimal oil saturation. These complexities hinder 3D development optimization and require tailored engineering solutions. Addressing these constraints through integrated geoscience-to-engineering workflows, we have advanced: multi-parameter sweet spot classification, geomechanical characterization for stress shadow management, and hydraulic fracture propagation modeling. For interwell communication mitigation, an integrated design framework coupling reservoir facies, natural fractures, stimulated fracture networks, and well spacing optimization has been implemented. This study establishes mathematical and numerical models coupling dual-scale nanopore oil-water nonlinear flow with stress-dependent effects in reservoirs and fractures. These models accurately characterize shale oil migration while minimizing deviations. For Yingxiongling Formation's thick shale oil reservoirs, well spacing patterns are optimized across distinct sweet spots and compartments to define key parameter thresholds that guide development deployment.