Evaluation of fluid-fluid and rock-fluid interfacial interactions using silica nanofluids and crude oil for a deepwater carbonate Pre-salt field

Abstract

Abstract The biggest challenges for E&P activities are the high viscosity of the oil, the geology of the formation, the high interfacial tensions (IFT) between fluids and the reservoir wetting conditions. Enhanced Oil Recovery (EOR) methods are applied to modify fluid-fluid and fluid-rock interactions in the reservoir, facilitating the oil displacement and, consequently, increasing the recovery factor. In this work, the use of silica nanofluids, with and without amphoteric surfactant, as EOR method to reduce the IFT and to change the wettability conditions of reservoir rock were evaluated. For experimental tests, crude oil from a reservoir in a Brazilian Pre-salt field was used as oleic phase. After data treatment, silica nanofluids (0.02 wt%) with surfactant (0.03 wt%) proved to be more effective in reducing the IFT of the system. However, the increase of silica nanoparticles (SiNPs) concentration promoted an increase in the IFT of the system, indicating a mechanical barrier effect. For nanofluids without surfactant, no significant change in IFT was observed with an increase in the concentration of SiNPs for both distilled water and brine (1,000 ppm) dispersant fluids. The significant reduction of the angle is observed for nanofluids with 0.02 wt% SiNP. Finally, the Amott test was performed in a carbonate rock sample to reaffirm the action of these chemicals in oil recovery, corroborating the potential of nanofluids to EOR applications. Thus, this work might contribute to a more rational design of nanoEOR strategies and technological innovations in carbonate reservoirs, especially those addressed to the South American Deepwater sector.