A fracture conductivity model for channel fracturing based on lattice-Boltzmann-method and computational-fluid-dynamics

This paper introduces a new method to predict fracture conductivity for channel fracturing by lattice-Boltzmann-method (LBM) and computational-fluid-dynamics (CFD). Firstly, the deformation of the proppant pillar is tested using uniaxial compression experiments. A non-uniform fracture width model considering the nonlinear deformation of fracture and the embedment of proppant pillars is established. Then, an improved model based on LBM-CFD is proposed to simulate the flow field within the fracture and calculate the fracture conductivity. Finally, parametric analysis is carried out to understand the effects of closure stress, elastic modulus of the reservoir rock, proppant pillar's shape and proppant pillar's spacing on fracture width and conductivity. The results showed that the conductivity decreases gradually with closure stress and increases with elastic modulus. The proppant pillar with the smallest shape ratio can provide the highest conductivity. When the ratio of the proppant pillar's diameter to spacing is about 0.5, the conductivity for channel fracturing is best. The time of proppant-laden fluid (PLF) pulse and proppant-free fluid (PFF) pulse are the keys to the successful implementation of channel fracturing. The simulation results have been applied to the optimization of the pulse time in Shengli Oilfield. The field application proves that channel fracturing design based on our method could result in a large increase in well production. This paper gives critical insights for predicting the conductivity for channel fracturing, which could serve as guidelines for the optimization of proppant pillar's parameters and pulse time in channel fracturing design. © 2022 Elsevier B.V.