Improved low-salinity waterflooding via a novel nanocomposite for wettability alteration, interfacial tension reduction, and colloidal stability enhancement in porous medium

This study introduces a novel surface-modified graphene oxide/silica nanocomposite, functionalized with polysorbate 20, to synergistically enhance colloidal stability, reduce interfacial tension, and alter wettability in low-salinity water. Detailed characterization (X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis) confirmed the successful synthesis of the nanocomposite. Zeta potential testing was used to investigate the stability of the synthetic compound. The results showed exceptional stability for the nanocomposite at −59.13 mV, which far exceeds that of its individual components. This high electrostatic stability prevents aggregation, ensuring a uniform dispersion essential for efficient transport in porous media. Core-flooding experiments demonstrated a significant 28% increase in overall oil recovery. This performance is attributed to the synergistic dual-action of the nanofluid: a dramatic wettability alteration from an oil-wet (153°) to a strongly water-wet (44°) state, and a substantial reduction in the oil-water interfacial tension to 1.36 mN/m. The results underscore that the integration of superior colloidal stability with potent interfacial activity in a single nanocomposite formulation presents a robust strategy for enhancing oil recovery, bridging the gap between nanoscale interactions and macroscopic flow efficiency. • A novel synergetic nanofluid GO/SiO2(/polysorbate 20) was synthesized. • The proposed nanofluid flooding yielded 28% incremental oil recovery. • Exceptional −59.13 mV zeta potential ensures well colloidal stability. • Wettability was altered from 153° (oil-wet) to 44° (water-wet). • Interfacial tension was reduced to 1.36 mN/m for oil mobilization.