Experimental study on interface properties and oil displacement efficiency of foams stabilized by SiO2 nanoparticles

Key words:  nano-SiO₂  interfacial rheological properties  microscopic model  sweeping volume  oil recovery efficiency

Abstract:

Foam flooding is proven to be an effective technique for improved oil recovery, but the stability of foam has limited its application. Nano-SiO₂ is therefore added into surfactant solutions to increase the foam 's stability. In this study, the surface tension and surface dilatational properties of a combined foam system SiO₂₊SDS were measured by a Tracker Interfacial Rheometer, and the mechanism of the foam flooding was investigated using a microscopic model in comparison with the SDS foam flooding. The effect of the nano-SiO₂ agent on oil displacement was also studied via core flooding experiments. The experimental results show that the stability of the foam and the surface dilatational viscoelasticity modules increase with the increase of mass fraction of SiO₂ nanoparticles. The enhanced foam stability can effectively prevent separation of gas and liquid, and increase the efficiency of foam plugging and sweeping. The enhanced surface dilatational viscoelasticity modules can increase oil displacement efficiency as demonstrated in the microscopic model experiments. The core flooding results show that both the oil recovery and the pressure drop increase with the increase of nano-SiO₂ mass fraction, and the oil recovery efficiency is 25％ higher than that of the SDS foam flooding.