Modeling of Proppant Placement in Hydraulic Fractures Including the Effects of Poroelasticity, Heat Transfer, Fracture Closure, and Temperature-Dependent Viscosity

Summary In this paper, we present a model for simulating proppant placement in hydraulic fractures, with the objective of better predicting proppant distribution as well as fracture conductivity. Integrated into the model are key transport mechanisms, including proppant settling, pack/bed formation, Darcy flow through the proppant pack, proppant bridging, and tip screenout. Proppant transport, settling, and embedment during shut-in (critical processes often overlooked in previous models) are considered. The model also incorporates the non-Newtonian characteristics of fracturing fluids and pressure-dependent fluid leakoff, and accounts for thermal effects on proppant transport and settling. The equations governing heat transfer and proppant transport are solved using the finite volume method. The model is applied to both conventional and unconventional reservoirs, followed by a sensitivity analysis. Simulation results show that proppant settling during shut-in can significantly affect the final distribution of proppant in tight formations, which in turn influences the residual fracture aperture and overall fracture conductivity. In highly permeable formations, high-viscosity fracturing fluids may trigger premature tip screenout, impeding further fracture propagation. The poroelastic effect can reduce fracture aperture and complicate proppant transport in the fracture. Additionally, the use of ultralight proppant in hydraulic fracturing treatments can effectively reduce proppant settlement, leading to a more uniform proppant distribution and a larger propped area.