Aqueous foam stabilized by partially hydrophobic nanoparticles in the presence of surfactant

Although foam has been widely used in petroleum industry, its instability is still a problem during its applications. Here, partially hydrophobic modified SiO2 nanoparticles were used with sodium dodecyl sulfate (SDS) to increase the foam stability. Surface tension, interfacial dilational viscoelasticity, and potential of SiO2/SDS aqueous dispersion had been determined and correlated with foam stability and plugging ability in porous media. The experimental results showed that SiO2 nanoparticle had a synergetic effect on foam stability with SDS at proper concentrations, and more stable foam could be obtained from SiO2/SDS dispersion compared to SDS solution. It is deduced that SDS molecules help the nanoparticles to move to air-liquid interface at moderate concentration, and thus the dilational viscoelasticity increased consequently. SiO2/SDS foam showed a good plugging performance in the sandpack flooding experiment. Foam stability was enhanced with nanoparticles adsorbed on the surface of liquid film, so bubbles did not rupture easily in porous media. As a result, more gas was trapped in the sandpack to prevent gas breakthrough. These fundamental results may guide the application of nanoparticle-stabilized foams in oil field. (C) 2015 Elsevier B.V. All rights reserved.