Phase behavior of EOR-Oriented dilutable Single-Phase microemulsions

Microemulsions demonstrate significant potential for enhancing oil recovery (EOR) owing to their remarkable abilities to reduce interfacial tension, alter wettability, and facilitate solubilization. However, the challenge remains in preparing dilutable single-phase microemulsions with large single-phase regions and tiny droplets. In this study, we developed an EOR-oriented single-phase microemulsion formulated using mixed nonionic-cationic surfactants. The system incorporated a biodegradable double-chain monosaccharide quaternary ammonium surfactant alongside a polyoxyethylene ether surfactant. D-limonene functioned as the oil phase, while propylene glycol butyl ether served as the co-surfactant. Transition regions and microstructures were revealed through conductivity tests and microscopic electron microscopy. Furthermore, the mechanisms of microstructure transition under various phase behaviors were explored by simulating the synergistic effects and interfacial distributions of mixed surfactants through molecular dynamics simulation.