Molecular Design, Synthesis and Oil Displacement Mechanism of Anionic-Nonionic Emulsifying Viscosity Reducer

Reducing heavy oil viscosity via emulsification is essential for enhanced recovery, yet conventional agents often underperform under complex reservoir conditions. A novel anionic–nonionic emulsifying viscosity reducer, featuring a benzene ring, sulfonic acid group, and tunable ethoxy chain, was synthesized through hydroxyl and halogen substitution reactions. Structural and thermal characterization ( 1 HNMR, FT-IR, TGA) confirmed the target compound. The optimized JH-10/Na 2 CO 3 system achieved ultralow interfacial tension (0.053 mN·m –1 ) and formed stable emulsions (∼40 μm). Core flooding tests demonstrated a displacement efficiency of 50.79%, while microscopic displacement efficiency reached 98.53%, surpassing commercial counterparts. Molecular dynamics simulations indicated that temperature-enhanced interfacial aggregation drives the superior emulsification and viscosity reduction performance. These results provide a highly effective, economically viable strategy for heavy oil recovery and reveal mechanistic insight into rational molecular design for viscosity reducers in challenging reservoirs.