CFD-DEM investigation on continuous invasion behaviors of particles and evolution of pore clogging in porous media

The phenomenon of particle migration and clogging in porous media is prevalent in geotechnical and petroleum engineering, particularly when involving continuous particle invasion and agglomeration processes that necessitate in-depth investigation. In this work, the two-way coupling Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) is employed to investigate the microscopic dynamic behaviors of particle continuous invasion and clogging by multiple invasion cycles at different fluid viscosities and friction coefficients of particles. The evolution of agglomerate formation and pore clogging are predicted through metrics including aggregation growth rate and development curves of penetrating particles. Results reveal that the particle clogging mechanisms transitions from point clogging within individual pores to surface clogging across multiple pores with the increase of invasion cycle. The retention of fine particles showed a continuous increment with an accumulation of over 80 % to 95 %. The severe damage after the second invasion cycle is predicted according to the decrease of normalized permeability to 0.33. The average translational velocity of particles increases together with fluid viscosity, thus reducing the particle penetration time and particle retention rate. At low fluid viscosity, particles exhibit a multi-point dispersed retention pattern, which promotes the formation of particle aggregates. Besides, the high-friction-coefficient particles experience stronger static friction force and sliding resistance at the pore throat, inhibiting their continued migration with fluid, which also decreases the average invasion depth and increases the particle retention rate. Decreasing the friction coefficients will improve particle aggregate growth rates and promote the formation of agglomeration.