Formulation and characterization of ionic liquid-based nanoemulsion for enhanced oil recovery applications

Ionic liquids (ILs) are gaining attention in enhanced oil recovery (EOR) due to their potential as emulsifiers for stable oil-in-water nanoemulsions. The unique properties and stability make them promising class of chemicals, but there is a notable lack of comprehensive studies on ILs based nanoemulsions for oil recovery. In present work two methods of emulsification viz. high energy and low energy method were utilized for nanoemulsion formulation. The properties of nanoemulsions were evaluated by droplet size, zeta potential, and stability analysis. The optimized nanoemulsion formulation was further studied for EOR by assessing its miscibility with crude oil, interfacial tension reduction, wettability change, and rheological properties. The prepared nanoemulsions exhibited droplet size in a nanoscale range which decreased with emulsifier concentration. The formulated nanoemulsion formulations revealed a significant higher value (>40 mV) of zetapotential of all the IL solutions indicates higher stability of the formulated nanoemulsions. The stability was further confirmed by multiple light scattering using Turbiscan stability analyser. The excellent miscibility of the optimized nanoemulsion with crude oil holds promise for enhanced oil recovery and industrial applications. A significant lower value interfacial tension (2 mN/m at 70 °C) was obtained at optimum formulation. The nanoemulsion also showed good wettability and altered the wettability of the rock from oil-wet to water-wet. The rheological studies of nanoemulsions showed good viscous behaviour which is desirable for improved sweep efficiency. A higher viscosity of nanoemulsion (5 cp at 30 °C and 3 cp at 30 °C) compared to water improves the macroscopic sweep efficiency. The findings of this study clearly demonstrate the ability to create extremely stable crude O/W nanoemulsion, which is desirable in enhanced oil recovery.