Nanoparticle/polymer-enhanced alpha olefin sulfonate solution for foam generation in the presence of oil phase at high temperature conditions

Foam flooding can improve oil recovery performance through reducing gas mobility in subsurface porous media. However, foam in porous media is thermodynamically unstable, especially in reservoir conditions where it is in contact with hydrocarbons (oil phase). In this study, the use of silica (SiO2) and rice husk ask (RHA) nanoparticles with xanthan gum (XG) and acacia gum (AG) polymers, is proposed to improve the foam stability at high temperature and high salinity conditions in the presence of oil phase. Moreover, it was highlighted that the potential use of RHA, extracted from waste materials, and natural acacia gum can substitute previously proposed synthesized nanoparticles and polymers as foam additives for immiscible displacement in subsurface porous media.

The results show that the addition of polymers do not change the surface tension at high temperatures, and its combination with nanoparticles can increase the viscosity of surfactant remarkably. It was found that an increase in the stability of CO2-foam can be achieved with increasing nanoparticles and polymer concentrations to optimum concentrations. Furthermore, foam stability increases with decreasing the nanoparticles sizes and increasing the molecular weight of the polymer.

In order to understand the performance of the optimum foam composition at high temperature and salinity conditions, the foam was brought into contact with a reservoir oil. It was shown that the CO2-foam stability in the presence of oil, could be enhanced by using nanoparticles and polymers, compared to the CO2-foam system with no additives. The reason for such improvement is due to the presence of nanoparticles and polymers in lamellae that break the oil into the emulsion droplets system that can flow easily through the lamellae without draining the entire surfactant solution from them.