Numerical simulations of proppant deposition and transport characteristics in hydraulic fractures and fracture networks

Proppants are used to resist fracture closure during hydraulic fracking treatments. Understand the proppant transport and distribution characteristics in fracture and fracture network become a meaningful topic for its effects on the conductivities of fractures. Since experiments are expensive, and it is also difficult to consider various conditions and detect the movement of particles during experiments, numerical simulation methods are often applied. In this work, the coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) was implemented to investigate the factors affecting proppant distribution in fracture and fracture networks. First, the CFD-DEM model was built for proppant flow and settlement. We validated the model by comparing with the published numerical simulation result. After that, we designed a series of cases to investigate the effects of fracture closure, injection velocity and no-uniform opening of the inlet on proppant distribution in a single fracture. Then, the effects of proppant diameter, density and perforation height differences on proppant sorting were studied. Next, we computed the proppant transport in fracture networks considering the aperture difference, the orientation of branch fractures and leak-off in fracture tips. The simulation results in this paper can help engineers to understand the transport and distribution of proppants visually in the fracture and fracture networks in unconventional reservoirs.