Simulation on detachment and migration behaviors of mineral particles induced by fluid flow in porous media based on CFD-DEM

The adhesion and detachment of mineral particles from host sandstone have a significant influence on their subsequent migration, deposition behaviors and the seepage characteristics of pore fluid in porous media. In this work, the effects of injected fluid velocity, porosity and adherent particle number on the detachment and subsequent migration behaviors of adhesive mineral particles are investigated using CFD-DEM method. The main focus is on the particle detachment behaviors from the host sandstone, subsequent migration mechanisms, and their effects on fluid seepage behaviors and hydraulic performance of porous media. The parallel bond model is used to analyze the force balance mechanisms of particle adhesion and detachment after verifying the accuracy of the numerical model through classical theoretical equations and experiments. According to the equilibrium relationship between fluid impulsive force and particle adhesion force, mineral particles can be divided into non-detached adhesive particles, detached-migratable particles and detached-deposited particles based on their existence states. The local fluid velocity near wall, especially at the corner, is significantly higher than that inside the pore due to the formation of dominant fluid channel. Results show that high injected fluid velocity facilitates both particle detachment rate and detachment intensity, which also accelerates the escape efficiency of detached particles. Low porosity accelerates the detachment of mineral particles, and the detached particles predominantly deposit rather than escape when porosity is below 30 %. Meanwhile, the detachment of particle is not contingent on the number of adherent particles, even though an increase in this condition leads to a greater number of particles being detached. The variations in pressure drop and absolute permeability are also investigated.