Pore-scale CFD simulations of clay mobilization in natural porous media due to fresh water injection

•A pore-scale model is presented to explain pore-clogging due to clay fines detachment.•Clay particles detaching in clusters from the grain surfaces cause permeability decline.•Represented clay-clay and clay-grain DLVO interactions by the immersed boundary method.•The simulations show critical salinity and velocity for the onset of clay detachment. The present work investigates mechanisms of permeability impairment as a result of low-salinity fluid injection into brine-saturated porous media containing dispersible clays. We present a computational fluid dynamics model at the pore-scale to simulate detachment, migration and straining of fine particles in porous media. The model uses an immersed boundary method to simulate the motion of clay fines in a fluid. In addition to the hydrodynamic forces, we model the Derjaguin-Landau-Verwey-Overbeek forces (DLVO) between clay fines and grains. Our simulations show the impact of the injected fluid’s salinity and velocity on the concentration of clay fines retained on the grain surface. We see clay particles dislodging from the grain surface in clusters of up to 12 particles. Our simulation results also demonstrate clogging of narrow pore spaces by the detached particles from the grain surfaces.