Dynamic evolution of stress interference during the multi-layer exploitation of sand-shale interacted continental shale oil reservoirs

Accurate prediction of stress evolution induced by production pressure depletion after hydraulic fracturing is essential for efficient development of stacked continental shale reservoirs. This study establishes a three-dimensional stress sensitivity and flow coupling framework to characterize intra-layer and interlayer stress evolution during shale oil development. A 3D discrete fracture network (DFN) integrating hydraulic and natural fractures was reconstructed from microseismic data obtained during multi-layer fracturing. Based on this, a stress sensitivity model for interbedded sandstone–shale reservoirs and a V-shaped well layout flow model was developed to simulate single-layer (three-well) and three-layer (nine-well) production scenarios. The reconstructed fracture network revealed that hydraulic fractures propagate laterally away from the zipper fracturing side and vertically upward toward low-pressure zones. During multi-layer development on Platform H, fracture intersections between the middle and adjacent layers produced 0–3 MPa pore pressure interference under different production schedules, indicating the need for optimized inter-well and interlayer spacing. Sandstone layers, characterized by higher permeability and porosity, exhibited a greater increase in horizontal stress difference (2.61 MPa) than shale layers (<0.5 MPa). Stress reorientation angles ranged from 5° to 38° in shale and from 16° to 64° in sandstone layers. These results demonstrate that well spacing should be larger in sandstone layers, whereas infill drilling is more suitable within shale intervals. The proposed modeling and analysis approach provides a theoretical and technical basis for optimizing well pattern deployment and maximizing energy utilization in shale oil reservoir development.