Interfacial behavior and enhanced oil recovery performance of amphiphilic silica Janus nanoparticles synthesized via Pickering emulsion.

Amphiphilic Janus nanoparticles (JNPs) are promising candidates for enhanced oil recovery (EOR) due to their dual-faced chemistry that enables interfacial activity and rock-surface modification. In this work, ultra-stable Silica Janus Nanoparticles (SJN) were synthesized using a novel Pickering-emulsion route. The synthesized silica NPs were characterized by SEM, XRD, FTIR, and DLS to confirm their morphology, structure, functional groups, and size distribution. Their performance was systematically compared with conventional and Unmodified Silica Nanoparticles (USN) through interfacial tension (IFT), wettability, adsorption, and micromodel displacement tests. Results showed that SJNs exhibited significantly higher surface activity at low concentrations, achieving 58.3% greater IFT reduction than USNs at 1000 ppm, and enhancing oil recovery to 47% compared with 29% for USNs. The mechanism of action is attributed to the amphiphilic Janus interface, where the hydrophilic side anchors in the aqueous phase and the hydrophobic side interacts with the oil phase, thereby lowering IFT, promoting wettability alteration, and stabilizing emulsions. These findings highlight IFT reduction and favorable adsorption as the dominant recovery mechanisms at the pore scale under ambient conditions, and suggest that SJNs merit further evaluation through core-flood testing under reservoir temperature, pressure, and salinity before field-scale application.