Surfactants are known as potential candidates for enhancing oil recovery by affecting interfacial tension and wettability in different types of oil reservoirs including sandstones and carbonates. The performance of these agents, may be improved (in terms of stability and activity) by addition of nanoparticles. In this study, titanium dioxide (TiO2) and silica (SiO 2) nanoparticles taken at different concentrations, were combined with two types of surfactants including cetyltrimethylammonium bromide (CTAB) and arabic gum (GA) and evaluated as the agents providing an enhanced oil recovery in a carbonate oil reservoir in Iran. The CTAB + SiO2, CTAB + TiO 2, GA + SiO 2, and GA + TiO 2 combinations were analyzed in terms of stability (zeta potential test), surfactant adsorption (UV-visible analysis, interfacial tension (IFT), and rock wettability alteration), and oil recovery (spontaneous imbibition experiment). TiO2 nanoparticles improved the stability of surfactant suspensions. Moreover, they reduced adsorption of surfactants on a crushed carbonate powder. The visualization of the water film thickness in the presence of oil and rock powder confirmed that the addition of nanoparticles modified the wettability to be more water-wet. In addition, the GA + TiO2 combination was proved to be the most effective in enhancing the oil recovery in the studied carbonate oil reservoir, showing a significant increase (up to 17%) compared to other studied suspensions in the spontaneous imbibition processes.

Keywords