Effects of water soluble ions on interfacial tension (IFT) between oil and brine in smart and carbonated smart water injection process in oil reservoirs

Water injection is one of the most popular oil recovery methods in oil industry. Investigations have been carried out to find a more effective oil recovery fluid since the first practices of water injection and the idea of low-salinity water or ‘smart water’ was subsequently introduced. The active ions in a smart water solution can significantly decrease the interfacial tension between oil and water in the reservoir; it also has the ability to change the reservoir rock wettability that in return can increase the recovery factor. Also, the carbonated brine injection causes the trapped oil to lose viscosity and increase its mobility. The current study is about smart water and carbonated smart water injection and sets out to investigate the effects of soluble ions on reducing the interfacial tension (IFT) between oil and water and then increasing the oil recovery factor. To achieve this purpose, eleven slats were dissolved in both formation and distilled water. The IFT was then measured by pendant drop method and the results are discussed. Furthermore, the effects of temperature and pressure on IFT are also investigated. We have obtained the optimum salt and concentration of salt for reducing the IFT and, on the other hand, we have investigated the effects of dissolved CO2 in ionic solution on IFT at different conditions. Finally, we have characterized the optimum conditions for the effects of water soluble ions on IFT between oil and brine in smart and carbonated smart water injection in a typical oil reservoir.