Study of the effect of clay swelling on the oil recovery factor in porous media using a glass micromodel

Formation damage due to incompatibility between the formation and injected low-salinity water decreases the relative permeabilities of oil and brine, increases residual oil saturation, and decreases oil recovery. In the presence of swelling clays, the shock effect of sudden water injection results in an increase in formation damage. Clay minerals may cause formation damage due to swelling and migration during the production of oil and gas. Therefore a good understanding of the damage mechanisms of clays helps us to prevent and remedy possible damage in reservoirs. In this work, the effect of clay swelling behavior on the oil recovery factor at the pore scale by using a glass micromodel was studied. A clay-coated micromodel with sodium bentonite as the swelling clay was prepared. Using an image processing technique, the ultimate oil recovery factors after flooding with low-salinity water (LSW) and high-salinity water (HSW) were estimated and the effect of clay swelling phenomena on the oil recovery factor was studied. Final residual oil saturation was higher when LSW was used as the injection fluid compared to when HSW was used, and in fact it can be said that clay swelling somehow inhibits the film flow of injection fluid and causes more oil to be bypassed in the micromodel.