Amphiphilic Nanoalumina for Heavy Oil Recovery

Amphiphilic Janus nanoalumina (JAL) was successfully prepared via asymmetric modification of γ-glycidoxypropyltrimethoxysilane (GPTMS)-pretreated hydrophobic nanoalumina using 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt (HAPS) and octadecyltrimethoxysilane (ODTMS) through an interfacial self-assembly method. The structural characteristics, thermal stability, and salt tolerance of JAL were systematically characterized. Results showed that JAL exhibited excellent dispersibility with a narrow particle size distribution centered at 102 ± 5 nm and strong electrostatic stabilization (ζ-potential: −52.8 ± 1.2 mV). The nanoparticles demonstrated remarkable salt tolerance, maintaining colloidal stability at salinities up to 50,000 mg/L. Interfacial tension measurements revealed that JAL effectively reduced oil–water interfacial tension to a minimum of 1.8 mN/m at the optimal concentration of 0.3 wt %. Emulsion stability tests showed the highest stability at 30,000 mg/L salinity (TSI < 2.0 after 24 h), attributed to the formation of an elastic-dominated interfacial film. Contact angle measurements confirmed JAL’s ability to induce wettability reversal from oil-wet (126.8°) to water-wet (68.0°) within 24 h. Core displacement experiments demonstrated that JAL significantly improved oil recovery by 18.7% original oil in place, particularly when injected at moderate initial water cut (∼50%), through synergistic mechanisms of mobility control and wettability modification. These findings confirm that JAL, with its unique amphiphilic asymmetric structure, holds great potential for enhanced oil recovery in high-temperature and high-salinity reservoirs.