Numerical analysis of proppants transport in tortuous fractures of shale gas reservoirs after shear deformation

For a better understanding of the proppants distribution in complicated hydraulic fractures, a numerical model was established to investigate the proppants transport in tortuous fractures after the shear displacement. First, a method combining the normal distribution random function and the random growth method was proposed to construct three-dimensional tortuous fractures. Because of the shear deformation, the tortuous fracture was divided into several branch channels, which was much more complicated than the parallel and smooth fracture. And then, proppants motion in tortuous fractures was simulated by the analysis of forces on proppants, considering the interaction between particles, between proppants and the slurry, and between proppants and the fracture surface. The accuracy of this model was verified by the comparison between the simulated result and the experimental observation. From the simulation under different conditions, it can be concluded that increasing the pumping rate and fracturing fluid viscosity and decreasing the proppant density are more effective ways to improve the proppant distribution compared with the increase of proppant concentration. However, problems of proppants distribution still remained by adjusting a single factor, which can be solved by the combination of multi-foctors. And the slurry pumping rate and proppant concentration needed to be optimized to avoid the sparse distribution of proppants in the fracture. This study is helpful to understand the mechanism of proppants transport in the complex fracture.