In-situ formulation of pickering CO2 foam for enhanced oil recovery and improved carbon storage in sandstone formation

Abstract

Compared to sole gas flooding, foam flooding provides superior mobility control, enhanced sweep, and greatly improved oil recovery from depleted oil reservoirs. However, since most modern oil reservoirs are located at higher depths and further away from foam generation units, it is becoming increasingly difficult to maintain foam stability, especially in modern deeper oil wells. Thus, in this study, an alternative study in foam formulation has been reported. Instead of preparing the foam at the surface and injecting it down the oil well, into the subsurface, the foam can be formed “in situ” by saturating the porous media downhole by foaming agents. The foaming agents in this study consisted of an anionic surfactant, sodium dodecyl sulfate (SDS), and the whole solution was stabilized by the addition of 1000 ppm PAM and varying concentrations of silica nanoparticles (NPs). The formed foam can then be pushed conventionally by chase water and provide increased oil recovery. Increasing NP concentration, initially improved foam stability as a higher number of NPs participated in strengthening the gas bubble. Insitu foam formation was also investigated for improving carbon storage in depleted oilfields. The injection rate of gas and the slug size of the foaming agent were varied to determine gas storage before the breakthrough. A lower flow rate was found to be more conducive for foam formation while increasing slug size had little effect on gas storability in the reservoir.