Wettability Alteration of Oil-Wet Carbonate Porous Media Using Silica Nanoparticles: Electrokinetic Characterization

Application of nanoparticles for wettability alteration offers a practical approach to resolve some surface-related problems encountered in the nowadays technological process. Examples are underground/subsurface engineering implications, including the enhanced oil recovery from the oil-wet carbonate reservoirs. However, the common wettability evaluating techniques such as contact angle and flotation cannot be representative of the dynamic phenomena occurring at the pore scale and hence are unable to give accurate information about the process. Therefore, in the present work, the electrokinetic evaluations are utilized to explore the wettability alteration of initially oil-wet carbonate rock using silica nanofluids at the porous media conditions. Significant efforts have been considered to design an in-house experimental setup to provide reliable results pertaining to the electrokinetic parameters at the different wetting states. Following the treatment of oil-wet calcite sands using silica nanofluids of different concentrations, the streaming potential coupling coefficient and zeta potential, as well as the excess surface charge, are evaluated. A mechanistic study (demonstrated by FESEM visualizations) along with some averaging schemes reveals that the change in the wettability of oil-wet porous media by silica nanoparticles does indeed affect the electrokinetic attributes of the studied system and thereby can be characterized.