Surfactant viscoelasticity as a key parameter to improve supercritical CO2 foam stability/foamability and performance in porous media

The performance of supercritical carbon dioxide (scCO(2)) foams in aquifer remediation and Enhanced Oil Recovery is negatively affected by the foam instability at underground conditions (elevated temperatures and pressures). In search of solutions, viscoelastic surfactants are considered as potential stabilizers beyond traditional surfactants. There are limited studies on the effect of viscoelasticity on foam static and dynamic properties[1-4]. We suspect that surfactant viscoelasticity would enhance scCO(2) foam performance in both bulk form and porous media. A systematic study, including surfactant rheology, foamability, stability, and foam performance in porous media, has been performed to demonstrate the impact of the viscoelasticity of different surfactant solutions on scCO(2) foam performance. The experimental results indicate that surfactant viscoelasticity improves the foam stability while increasing the foamability up to an optimal point, where any further increment in viscoelasticity causes a reduction in foamability. Further, foam flooding performance was positively affected as the foamability of the surfactant solution increased. The results presented in this work advances our understanding of the viscoelasticity effect of surfactants on scCO(2)-foam performance in porous media and provides a path for optimization of these fluids for underground applications.