Enhanced oil recovery performance of surfactant-enhanced Janus SiO2 nanofluid for high temperature and salinity reservoir

Abstract

To improve the dispersion stability of the nanofluid, SDS/Tween 60 surfactant solution was employed as the dispersant for the Janus SiO2 nanofluid. The compounded system showed good dispersion stability and oil displacement effect at high temperature (90 ℃) and high salinity (35000 ppm). The amphiphilic Janus SiO2 nanoparticle was synthesized by Pickering emulsion method. Next, by introducing SDS/Tween60 surfactant system as a dispersant agent, the Janus SiO2 nanofluid could disperse well for more than 12 h at 90 ℃ with a salinity of 35000 ppm. The surfactant-enhanced Janus SiO2 nanofluids showed good dispersion stability in different characterization methods, including visual observation, Turbiscan stability index (TSI) and particle size. Based on the adsorption experiments, the optimal mass concentration ratio between surfactant and Janus nanoparticles was fixed at 2:1. The possible dispersion and stability mechanism of Janus SiO2 nanoparticles was explained from the perspective of the synergistic effect, between surfactants and nanoparticles and between surfactants and surfactants. Then, interfacial tension reduction ability, emulsion stability and wettability alternation capability of surfactant-enhanced Janus SiO2 nanofluid with various concentrations, were studied at 90 ℃ with a salinity of 35000 ppm. The surfactant-enhanced Janus SiO2 nanofluid, with a nanoparticle concentration of 0.01 wt%, showed the best EOR performance. The current study provides a new prospective in preparing Janus SiO2 nanofluids applied for enhanced oil recovery in high temperature and high salinity reservoirs.