Propagation characteristics of multiple clusters of fractures in fully coupled wellbore-perforation-fracture fracturing

Based on the Low Frequency Distributed Acoustic Sensing (LF-DAS) fiber optic monitoring and downhole hawk-eye imaging, the fluid and sand distribution and perforation erosion of all clusters during hydraulic fracturing were evaluated, and then a fully coupled wellbore-perforation-fracture numerical model was established to simulate the whole process of sand-carrying fluid migration and analyze key influencing factors. The proppant and fracturing fluid exhibit divergent flow pathways during multi-staged, multi-cluster fracturing in horizontal wells, resulting in significant heterogeneity in the fluid-proppant distribution among clusters. Perforation erosion is prevalent, and perforation erosion and sand inflow ratio have phase bias. The trajectory of proppant transport is controlled by the combined effects of inertia of particle migration and gravity settlement. The inertial effect is dominant at the wellbore heel, where the fluid flow rate is high, hindering particles turning into perforations and causing uneven sand distribution among clusters. The gravity settlement is more pronounced toward the wellbore toe, where the fluid flow rate is low, leading to enhanced phase-bias of slurry distribution and perforation erosion. Increasing the pumping rate reduces the influence of gravity settlement, mitigating the phase bias of sand inflow and perforation erosion. However, the large pumping rate limits the sand inflow efficiency near the heel clusters, and more proppants accumulate towards the toe clusters. High-viscosity fluids improve particle suspension, achieving more uniform proppant placement within wellbore and fractures. Larger particle sizes exacerbate sand inflow differences among clusters and perforations, limiting the proppant placement range within fractures.