title: Wettability alteration of oil-wet carbonate by silica nanofluid.
abstract: Changing oil-wet surfaces toward higher water wettability 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. A wettability change toward more water-wet would significantly improve oil displacement efficiency, and thus productivity. Another area where such a wettability shift would be highly beneficial is carbon geo-sequestration, where compressed CO2 is pumped underground for storage. It has recently been identified that more water-wet formations can store more CO2. We thus examined how silica based nanofluids can induce such a wettability shift on oil-wet and mixed-wet calcite substrates. We found that silica nanoparticles have an ability to alter the wettability of such calcite surfaces. Nanoparticle concentration and brine salinity had a significant effect on the wettability alteration efficiency, and an optimum salinity was identified, analogous to that one found for surfactant formulations. Mechanistically, most nanoparticles irreversibly adhered to the oil-wet calcite surface (as substantiated by SEM-EDS and AFM measurements). We conclude that such nanofluid formulations can be very effective as enhanced hydrocarbon recovery agents and can potentially be used for improving the efficiency of CO2 geo-storage.
authors.affiliation: Department of Chemical Engineering, Curtin University, Kent Street, 6102 Bentley, Australia. Electronic address: sarmad.al-anssari@postgrad.curtin.edu.au.
authors.forename: Sarmad
authors.initials: S
authors.lastname: Al-Anssari
authors.affiliation: Department of Chemical Engineering, Curtin University, Kent Street, 6102 Bentley, Australia; Department of Petroleum Engineering, Curtin University, 26 Dick Perry Avenue, 6151 Kensington, Australia.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Barifcani
authors.affiliation: Department of Chemical Engineering, Curtin University, Kent Street, 6102 Bentley, Australia.
authors.forename: Shaobin
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Exploration Geophysics, Curtin University, 26 Dick Perry Avenue, 6151 Kensington, Australia.
authors.forename: Lebedev
authors.initials: L
authors.lastname: Maxim
authors.affiliation: Department of Petroleum Engineering, Curtin University, 26 Dick Perry Avenue, 6151 Kensington, Australia.
authors.forename: Stefan
authors.initials: S
authors.lastname: Iglauer
keywords: Carbonate reservoirs; Nanoparticles; Silicon dioxide; Wettability