Fully Coupled Multi-Scale Geomechanical Modeling for Hydraulic Fracture Optimization and EOR Improvement

Abstract When developing Block D with small well spacing, severe stress interference occurs between wells. Optimizing fracturing operation parameters and clarifying the fracture propagation patterns post-fracturing are key to enhancing development efficiency. To mitigate inter-well and inter-cluster stress interference in the multi-layer, three-dimensional well network fracturing of Block D with small well spacing, and to reduce repeated stimulation, a detailed geological model was established based on fracture characteristics and in-situ stress distribution. Under the constraints of this model, a geomechanical integrated fracturing numerical model was developed using a software platform. Based on this model, studies were conducted to optimize fracturing parameters such as proppant volume, cluster spacing, and well spacing. The results indicate that the optimal proppant volume is 1600 m³, the reasonable cluster spacing is 6 m, and the optimal well spacing ranges from 200 to 250 m. Field microseismic monitoring showed a 91.2% agreement with the simulated fracture network, demonstrating that the geomechanical integrated fracturing model accurately reflects the actual underground fracture network. Post-fracturing, three types of fracture networks were formed: "hydraulic main fracture", "hydraulic main fracture + natural fracture", and "natural fracture". The study area primarily features a "hydraulic main fracture" type fracture network, with post-fracture half-lengths concentrated between 70 to 105 meters, and fracture heights mainly ranging from 20 to 30 meters. Although reducing well spacing and cluster spacing can increase the number of "hydraulic main fracture" type networks, achieving greater half-lengths and fracture heights, and thus more thoroughly modifying the reservoir, it also greatly increases the risk of inter-well channeling, leading to potential losses in final recovery rates.