Formulation and characterization of nanoemulsions stabilized by nonionic surfactant and their application in enhanced oil recovery

Nanoemulsions are kinetically stable emulsions with droplet size distribution in the range of 10-500 nm. Low interfacial tension (IFT), small droplet size, and wettability alteration properties of nanoemulsions have led to their application for enhanced oil recovery (EOR) EOR. The current study deals with the formulation and characterization of Tergitol 15-S-9 surfactant stabilized oil/water nanoemulsion (NE). Optimal surfactant concentration accompanied by optimal salinity determination was done by observing long-term stability. The stability of the nanoemulsions was analyzed by Turbiscan and Zeta potential analysis. The optimal nanoemulsion was characterized in terms of droplet size, rheology, wettability, miscibility, and IFT. All the prepared nanoemulsion showed particle size < 300 nm. optimized nano emulsion, that is, 0.5 wt.% surfactant +0.5 wt.% salinity showed good IFT reduction and wettability alteration capability. Nanoemulsion also showed good miscibility behavior with actual crude oil at 60 degrees C. Rheology of the formed emulsion shows a mixed nature that is shear thinning as well as shear thickening nature which is favorable for heterogeneous reservoirs. Core-flooding experiments were conducted at optimized nanoemulsion formulation, and additional oil recovery of 13.93% of the original oil in place was obtained after the conventional water flooding.

Automated summary

This study focuses on the formulation and characterization of a stable oil/water nanoemulsion using Tergitol 15-S-9 surfactant. The optimal surfactant concentration and salinity were determined through long-term stability observation. The nanoemulsion showed good IFT reduction, wettability alteration capability, and miscibility with crude oil, making it suitable for enhanced oil recovery.