Synthesis and characterization of a highly hydrophilic nanocomposite for wettability alteration, water/oil interfacial tension reduction, and enhanced oil recovery

Abstract

The development of stable nanofluids (NFs) for enhanced oil recovery (EOR) relies on optimizing interactions between reservoir rocks and fluids. In this manuscript, a new hydrophilic nanocomposite (NC) of zinc oxide, titanium dioxide, cetyltrimethylammonium bromide (CTAB), and polydopamine was synthesized. The novelty of this work lies in the unique multicomponent design that leverages the synergistic action of polydopamine properties and CTAB surfactant functionality, creating a stable agent with dual functionality for superior EOR performance. The NCs structural and morphological properties were characterized using field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Interfacial behaviour was quantified via contact angle (CA), and interfacial tension (IFT), and core flooding measurements. The results showed that a 70 ppm NC concentration achieved optimal performance, identified through a systematic experimental design. At this concentration, the NF exhibited a strongly negative zeta potential of approximately −50 mV, confirming excellent colloidal stability. It reduced the oil–water IFT from 22 to 1.98 mN/m and altered the contact angle on aged carbonate plates from 155° (oil-wet) to 19° (strongly water-wet). Core flooding tests showed a significant 35% increase in oil recovery over the low-salinity water flood baseline, recovering an additional 26% of the original oil in place (OOIP). Stability testing was also performed through zeta potential analysis. The NCs stability and dual functionality wettability alteration and IFT reduction are attributed to polydopamine properties and cetyltrimethylammonium bromides surfactant action at the oil/water interface. These results underscore the NCs potential as a scalable solution for nano-EOR, with broader applications in subsurface energy.