M Veisi - Department of Chemical Engineering, Sahand University of Technology, Tabriz, Iran
A.R Tabatabaei Nejad - Department of Chemical Engineering, Sahand University of Technology, Tabriz, Iran
E Khodapanah - Department of Chemical Engineering, Sahand University of Technology, Tabriz, Iran
H Eshghi - Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran

More than 60% of the world’s discovered oil reserves are held in carbonate reservoirs, which are mostly naturally fractured. Changing in wettability of oil-wet surfaces toward higher water-wet is of key importance in subsurface engineering applications. This includes petroleum recovery from fractured limestone reservoirs, which are typically mixed or oil-wet, resulting in poor productivity as conventional waterflooding techniques are inefficient. To take into view of negative capillary forces, injected brine cannot penetrate simply into an oil-wet matrix of fractured formations to force the oil out. A wettability alteration toward more water-wet would significantly improve oil displacement efficiency, and thus productivity.In this study, the effect of Fe2O3-based nanofluids on the wettability alteration of a carbonate reservoir rock was experimentally studied. Four concentrations of nanofluids were made composed of Fe2O3 nanoparticles. The effect of nanofluids on the wettability of carbonate samples were investigated by measuring the contact angles, and it was shown that nanofluids could change the wettability of the rock from an oil-wet condition to a neutral-wet condition. Scanning electron microscopy (SEM) images data verify adsorption of nanoparticles on the rock and formation of nanotextured surfaces.

Carbonate reservoir, Wettability alteration, Fe2O3 Nanofluid, Oil-wet, Water-wet