Numerical Simulation Study of Proppant Migration and Settlement Behavior in Complex Fractures

Hydraulic fracturing is one of the main technologies for developing unconventional oil and gas resources. Effective placement of proppant in the fracture has an important impact on the formation of channels with high conductivity. In order to study the migration and settlement law of proppant in complex fracture, computational fluid dynamics (CFD) is used to simulate the migration process of proppant in fracture, and drag and lift models are added in the simulation process. The proppant migration and settlement law under different impact factors is analyzed from three dimensions: sand dune length ratio, maximum height ratio of sand dune and sand dune area ratio. The simulation results show that the proppant tends to enter and settle in the branch fracture close to the entrance of the main fracture. When the main-branch fracture angle is smaller, the proppant is more likely to be carried into the branch fracture for settlement. When the fracture is inclined downward, the sand dune pattern in the main fracture moves to the depth of the fracture as a whole, which is not conducive to the effective filling of proppant near the wellbore. Increasing the viscosity and injection rate of fracturing fluid, the proppant migration trends in the main fracture and branch fracture are different. The numerical simulation results and conclusions will provide reference for the optimization of fracturing construction in the field. 1. INTRODUCTION Unconventional oil and gas resources have gradually become the focus of development (Liao et al., 2022). The unconventional oil and gas resources are mainly shale oil and gas, tight sandstone oil and super heavy oil (Meng et al., 2023; Ardakani et al., 2022). The rock properties of shale and sandstone make sand fracturing technology as the preferred measure for reservoir stimulation (Hou et al. 2014; Zhao et al., 2012). Successful sand fracturing requires effective fluid flow channels in the fracture (Yao et al., 2022). At the same time, a large amount of proppant is injected into the fracture to support the fracture and prevent it from closing.The migration and settlement trend of proppant directly affects the hydrofracture morphology and conductivity after fracturing. Therefore, it is necessary to study the impact of different factors on proppant placement during fracturing.