Study of Particle Structure and Hydrophobicity Effects on the Flow Behavior of Nanoparticle-Stabilized CO2 Foam in Porous Media

Abstract

Studies of supercritical CO2 foam stabilized with amorphous and crystalline silica nanoparticles at reservoir conditions were carried out for the CO2 foam enhanced oil recovery (EOR) application. In this paper, three types of silica nanoparticles, consisting of crystalline and amorphous structures, as well as different wettabilities, were employed to study the effects of particle structure and wettability on supercritical CO2 foam generation. The effects of silica nanoparticle structure and hydrophobicity on supercritical CO2 foam behaviors such as foam morphology, foam resistance factor and mobility were investigated under the conditions of a wide range of phase ratios and total flow rates. Our results showed that CO2 foams stabilized by crystalline silica and amorphous silica exhibit similar flow behaviors. The hydrophobicity of nanosilica plays the most important role for CO2 foam generation; the CO2 bubble size decreased significantly with the increase in hydrophobicity of silica nanoparticles. The silica nanoparticle with the highest hydrophobicity shows the greatest reduction of foam mobility under the conditions of wide-ranged phase ratios and total flow rates.