Enhancing Aqueous Stability of Anionic Surfactants in High Salinity and Temperature Conditions with SiO Nanoparticles.

In chemical-enhanced oil recovery (cEOR), surfactants are widely used but face significant stability challenges in high-salinity brine, where they often degrade or precipitate. Existing methods, such as adding cosurfactants, offer limited compatibility with anionic surfactants and raise economic concerns, creating a need for more robust solutions. This study introduces a novel approach to enhance the stability of anionic surfactants in extreme salinity conditions by incorporating silicon dioxide (SiO) nanoparticles (NPs). Our optimized formulation effectively prevents surfactant precipitation and NP aggregation, demonstrating stability in brine with salinity as high as 57,000 ppm and temperatures up to 70 °C, thus addressing the salt tolerance issues seen with conventional anionic surfactants like sodium dodecyl sulfate (SDS). To validate our formulation, we employed multiple experimental techniques, including turbidity, ζ-potential (ZP), and hydrodynamic diameter (HDD) measurements, which confirmed the efficacy of our approach. Results indicated that an optimal SiO NP concentration (0.01 wt %) significantly enhanced SDS stability, with no observed aggregation or precipitation over 7 days. High absolute ZP values (>25 mV), a small HDD (∼37 nm), and a consistent turbidity profile underscored the stability and dispersion of the formulation. This nanoparticle-based method offers a cost-effective and sustainable solution for cEOR, providing enhanced surfactant stability and improved NP dispersibility under high-salinity and high-temperature conditions, representing a valuable advancement in chemical-enhanced oil recovery technology.