Preparation and characterization of modified amphiphilic nano-silica for enhanced oil recovery

In this study, 3-aminopropyltriethoxysilane (APTES) and octyltriethoxysilane (OTES) reacted with nano-silica (NS), and the hydrophobicity, wettability and oil displacement performance of the modified nanoparticles (OAS) were changed by adjusting the amount of OTES. The synthesized amphiphilic silica was characterized by elemental analysis, flourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TG) and transmission electron microscopy (TEM). The results showed that the modification of silica was successful and showed different changes with the increase of the amount of modifier OTES. Besides, zeta potential, particle size measurement and transmission electron microscopy results show that OAS particles can maintain good stability. OAS-3 particles can change the core wettability from oil wet to neutral wet, and can significantly reduce the interfacial tension, which reduce the interfacial tension from 14.9 mN/m to 10.4 mN/m. In addition, the OAS particles also have a good emulsification effect, which can keep the emulsion stable for a long time. In the core flooding experiment, the modified amphiphilic silica particles can improve oil recovery. Compared with NS, OAS-3 particles have the best oil displacement effect, and the oil recovery can be increased by 10.3%. which has a certain potential in the application of enhanced oil recovery.