Preparation and application of pH-Responsive and high salt-tolerant silica-based amphiphilic Janus nanosheets for enhanced heavy oil recovery

Enhanced oil recovery and stimulate corresponding oil-water separation are crucial for the development of heavy oil resources. Herein, amphiphilic silica-based Janus (JNs) nanosheets with amino/phenyl groups on both sides (Ph-SiO2-NH2 JNs) are synthesized by sol-gel method. As a result, dynamic interfacial tension (IFT), particle size distribution and separation rate reveal that Ph-SiO2-NH2 JNs nanosheets (0.05 wt%) enable to effectively decrease the IFT between heavy oil and water (2.71 mN/m). Ph-SiO2-NH2 JNs nanosheets form a stable emulsion between heavy oil and water, which still maintains outstanding stability under the salinity of 1.55 × 104 mg/L. Meanwhile, it exhibits pH-response performance, which can stabilize heavy oil emulsion in acidic medium (pH = 2) and realize oil-water separation in neutral medium (pH = 7). And the oil recovery of 15.54% is obtained by an injection of 0.03 wt% Ph-SiO2-NH2 JNs nanosheets. Therefore, the construction of silica-based JNs nanosheets is potential for the development of heavy oil sources.