Enhancing Oil Recovery with Shape-Modified Silica Nanoparticles: Efficiency in Oil-Wet Sandstone Reservoirs via Imbibition and Micromodel Approaches

This study investigates the use of shape-modified silica nanoparticles functionalized with sodium (C14–16) olefin sulfonate (SOS) for enhancing oil recovery in oil-wet sandstone reservoirs. Characterization techniques, including scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), Thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR), verified successful surface modification. Functionalization reduced the mean particle size from 188 ± 15 to 98 ± 14 nm and enhanced stability, with zeta potential increasing from −11 to −46 mV. Nanoemulsion tests showed that SOS-functionalized nanoparticles achieved the lowest creaming degree and produced smaller oil droplets. The interfacial tension between crude oil and SOS-functionalized nanoparticles decreased from 24 to 1 mN/m, with further reductions observed upon the addition of alkali. Wettability alteration was also achieved, with contact angles shifting from 20° (oil-wet) to 173° (strongly water-wet) in the presence of SOS-functionalized nanoparticles. Spontaneous imbibition tests demonstrated oil recoveries of 77% with SOS-functionalized nanoparticles, outperforming SOS alone (42%) and unmodified nanoparticles (35%). Micro-CT scanning of the samples after imbibition test showed lower pore connectivity reduction with SOS-functionalized nanoparticles (31%) compared to unmodified nanoparticles (59%). Micromodel flooding tests confirmed enhanced oil recovery, with SOS-functionalized nanoparticles achieving 86% recovery compared to SOS (38%) and unmodified nanoparticles (18%). This study highlights the potential of SOS-functionalized silica nanoparticles to improve oil recovery in oil-wet sandstone reservoirs through wettability alteration, interfacial tension reduction, and stabilized emulsions.