Particulate transport in porous media at pore-scale. Part 2: CFD-DEM and colloidal forces

Pore-clogging by aggregation of fine particles is one of the key mechanisms in particulate transport in porous media. In this work, the unresolved-resolved four-way coupling CFD-DEM (Computational Fluid Dynamics- Discrete Element Method) proposed in Part 1 is coupled with colloidal forces (long-range interactions) to model the transport of charged particles and retention by aggregation at the pore-scale. The model includes hydro-mechanical interactions (e.g. collision, drag, buoyancy, gravity) and electrochemical interactions (e.g. Van der Waals attraction, electrostatic double layer repulsion) between the particles, the fluid, and the porous formation. An adhesive contact force based on the Johnson-Kendall-Roberts theory allows for realistic particle adhesion on the walls. The model robustness is verified using reference semi-analytical solutions of the particle dynamics including long-range interactions. Finally, our CFD-DEM for particulate transport including DLVO and JKR adhesive contact forces is used to investigate the effect of fluid salinity on pore-clogging and permeability reduction. Importantly and unlike other approaches, our CFDDEM model is not constrained by the size of the particle relative to the cell size. Our pore-scale model offers new possibilities to explore the impact of various parameters including particle size distribution, particle concentration, flow rates, and pore geometry structure on the particulate transport and retention in porous media.