Numerical Simulation of Multicluster Fracture Propagation in Shale Gas Reservoirs under the Coupled Influence of Geological and Engineering Parameters

Deep shale in the Sichuan Basin holds rich gas resources, whose effective exploitation relies on optimized hydraulic fracturing. Fracture generation and propagation establish high-conductivity flow paths, and the effective growth of multiple fracture clusters is essential for deep shale reservoir reconstruction. A fracturing numerical model considering multilayer interlayer stress differences and rock mechanical differences was constructed using the discrete lattice method (DLM). The reliability was demonstrated through mutual verification between experiments and numerical simulations. On this basis, a systematic research was conducted on the competitive initiation and propagation laws of multi─clusters under the coupled influence of geological and engineering parameters in deep shale reservoirs. The results show that the established fracturing model can accurately capture the competitive propagation behavior across vertically layered formations. The cluster spacing dominates the stress shadow effect and jointly controls the fracture morphology transformation with the reservoir thickness. When the Young’s modulus increased from 10 to 50 GPa (with cluster spacing of 20m), the fracture height increase 76.41%. The high-viscosity fluid (9 cP) would cause the total area to decrease by 11.99% with a high modulus environment. Meanwhile, increasing the cluster spacing at a low displacement (3 m3/min) may inhibit crack initiation, while a high displacement (15 m3/min) can break through the stress interference limit and increase the crack area by 312.23%. The results will provide theoretical guidance for on-site construction in deep shale gas reservoir.