In this research, we have investigated wettability alteration of sandstone and crude oil surfaces contacting nanofluids formulated by ZnO nanoparticles. The ZnO nanofluid was mixed by dispersing into water solution of Sodium Dodecyl Sulfate that is an anionic surfactant. ZnO concentration (w/w) in the fluid ranges from 500 ppm to 5000 ppm. Oil film spread on glass plate and surface of Berea sandstone saturated by light crude oil were used to measure fluid wettability evaluated by the contact angle of fluid droplets with the sessile drop methods. It has been confirmed that the ZnO nanofluid has a potential to shift wettability to more water wet condition on the surfaces of oil film and sandstone saturated by oil.
The uses of nanoparticles are raised an interest in petroleum industry recently. This is so because nanoparticles have a proven potential to decrease the interfacial tension (IFT) and change the wettability state of formation rock from strongly oil-wet or oil-wet to water-wet or to strongly water-wet. Wettability is defined as the relative adhesion of two fluids to a solid surface. In petroleum reservoirs, wettability is one of important factors that effect on production increment in oil recovery, because it is a major target of the enhanced oil recovery process. Al-Anssari et al. (2016) have studied about wettability alteration of oil-wet carbonate by silica nanofluid and their result show that rock surface wettability shifts from oil-wet to water-wet. Sepehrinia and Mohammadi (2016) conducted a research on aluminum oxide and zirconium oxide on oil-wet dolomite surface with different dispersing medium such as cationic, anionic or nonionic surfactant. Their result showed that cationic surfactant is more effective in altering wettability of oil-wet dolomite rock to more water-wet condition.
In this study, the nanofluid formulated by ZnO nanoparticles with anionic surfactant Sodium Dodecyl Sulfate (SDS) (ZnO nanofluid) was investigated to use for enhanced oil recovery by IFT reduction of residual crude oil in sandstone reservoirs.
