Effecting factor analysis to stability of ultra-dry CO2-in-water foams stabilized with zwitterionic surfactants, polymers and nanoparticles

The application of ultra-dry CO 2 -in-water (C/W) foams for the displacement of water-sensitive reservoirs can achieve the double benefits of CO 2 sequestration and enhanced oil recovery (EOR). In this work, ultra-dry C/W foams with 4% v/v water were generated by Cocamidopropyl betaine (CAPB), Nonionic poly(acrylamide) (NPAM) and hydrophobic or hydrophilic nanoparticles (NPs) with different specific surface areas. The foam prepared with hydrophilic NPs exhibited the optimal temperature resistance. Rheological experiments of solutions manifested the characteristics of shear thinning and confirmed the viscoelastic network structure (gel-like behavior). Interfacial tension (IFT) mainly affected the possibility of foam formation but was uncorrelated with foam stability. The density distribution, interfacial shear viscosity and interfacial thickness that were challenging to measure experimentally were obtained through dissipative particle dynamics (DPD) simulations. The results demonstrated that NPs could strengthen the interfacial film by forming a viscous network and generating steric resistance, thus enhancing the foam stability.