Reduction of Residual Oil in Oil-Wet Carbonate Formations by Application of Hybrid Smart Water/Silica Nanofluid Enhanced Oil Recovery Method

Smart water flooding has recently been considered as an attractive EOR method due to its lack of expensive chemicals. Alterations in oil/brine/rock interactions in porous media, such as wettability by smart water, affects oil recovery. Different mechanisms, such as wettability alteration, changes in the viscosity, changes in the interfacial tension and control of small particle migration, make nanofluid injection an effective method. In this study, the injection of a combination of smart water and silica nanoparticles is investigated for EOR. Different characterization measurements, such as contact angle, interfacial tension, zeta potential, X-ray diffraction, viscosity and core flooding are performed to investigate the effect of the developed method on oil recovery and the mechanisms changing sweep efficiency. Our results show that the highest oil recovery is achieved by the injection of smart water with a high concentration of sulfate ions combined with silica nanoparticles with a concentration of 0.1 wt.%. The addition of silica nanoparticles to smart water improves the wettability alteration mechanism, as well as increasing the fluid viscosity and affecting the sweep efficiency. Therefore, the application of the developed hybrid method exhibits distinct advantages compared to stand-alone smart water flooding.