Experimental insights into synergestic SiO2 nanoparticle/welan gum: the role of surface interaction in improving oil recovery

This study explored the synergistic interaction of SiO₂ NPs and Welan gum for offshore application. Interaction characteristics, rheological behavior, Fluid-rock interaction and oil displacement were evaluated. FTIR, SEM and H-NMR were employed to characterize the SiO₂-Welan gum solution. The results showed that SiO₂ interacts with Welan gum through chemical bonds and possible hydrogen bonds due to hydroxyl group formation, increasing polymer roughness and causing network disruption. The incorporation of SiO₂ NPs into welan gum resulted in a viscosity enhancement of up to 50% at 1.5 wt% salinity, demonstrating significant stability improvement. SiO₂ NPs contribute to the thermal resistance of the polymer at elevated temperatures. Their synergistic effect was to mitigate salinity-induced viscosity reduction, maintaining fluid consistency more effectively than in the absence of nanoparticles. With SiO₂, the adsorption between polymer and limestone decreased over time, showing an average reduction of 19%. The adsorption was homogeneous and was best described by the Langmuir isotherm model. The oil recovery improved by 15% more efficiently than the welan gum alone. The study suggests that SiO₂ interacts with Welan gum in the ionic solution creating a three-dimensional network that resists conformational collapse and controls the polymer diffusion in limestone porous media.