Particle-water-oil transport and interaction in weakly consolidated reservoirs using discrete element and volume of fluid coupled method

When developing weakly consolidated reservoirs by horizontal wells and facing the problems of sand production and water breakthrough, a poor understanding of the particle-water-oil transport and interaction mechanisms in the porous media can seriously affect the comprehensive benefits of well production. In this paper, an unresolved discrete element method-volume of fluid (DEM-VOF) coupling method is proposed for the oil-water two-phase flow containing fine particles within a pore-scale porous media. The method is characterized by the discrete element method calculation for particle displacements and collisions, the volume of fluid method for fluid flow and free surface capture, and a porous sphere model for calculating the local porosity of the fluid to overcome the difficulty in calculating the volume fraction when the particle size being larger than the fluid mesh. The accuracy of the coupled method was verified by a series of single particle sedimentation cases. The model reveals the microscopic mechanism of particle-water-oil transport within the porous media, and the results show that the presence of particles perturbs the oil-water interface, resulting in a lower average oil content volume fraction within the porous media during water drive. The production of particles also increases due to the greater pressure difference and drag force associated with water drives. The permeability decrease due to particle migration in porous media is proportional to particle diameter and inversely proportional to fluid flow rate and fluid viscosity. This study provides a coupled computational method for analyzing the interaction between particles and multiphase fluids.