Numerical Simulation of Proppant Placement in Scaled Fracture Networks

Abstract

Abstract While hydraulic fracturing is recognized as the most effective stimulation technique for unconventional reservoirs, the production enhancement is influenced by several factors including proppant placement inside the fractures. The goal of this work is to understand the proppant transport and its placement process in T-shaped fracture network through simulations. The proppant transport is studied numerically by coupling a computational fluid dynamic model for the base shear-thinning fluid and the discrete element methods for proppant particles. A scaling analysis has been performed to scale down the model from field scale to lab scale by deriving relevant dimensionless parameters. Different proppant size distributions and injection velocities are considered, as well as the friction and cohesion effects among particle and fracture surface. The simulation results show that in the primary fracture, the injected proppant could divide into three layers: the bottom sand bed zone, the middle rolling surface zone, and the top slurry flow zone. The total number of the proppants do not increase much after the dune reach an equilibrium height. The equilibrium height of sand dune in the minor fracture could be greater than the primary fracture, and the distribution of proppant dunes is symmetric. Two deposit mechanisms have also identified in the bypass fracture network: falling deposition and rolling deposition. Additionally, significant momentum changes due to the change in the flow direction at the intersection with natural fractures is identified as a potential factor in accelerating particle deposition.