Nanosilica-stabilised supercritical carbon dioxide foam for enhanced oil recovery application

Abstract

Various enhanced oil recovery (EOR) methods have been studied intensively and proven to mobilize, and aid in improving the flow of remaining oil in the reservoirs to producing wells, thus leading to better oil recoveries. Gases have been commonly used in EOR, such as natural gas, carbon dioxide (CO2), and nitrogen while CO2 is the most commonly used gas. Foam flooding has started to gain more interests in the field for its promising gas mobility reduction. However, foam generated with surfactant suffers instability under harsh reservoir condition, such as high pressure, high temperature and high salinity. Nanoparticle has then come into play for the role to stabilise foam and several studies on the subject have shown favourable results. Nevertheless, nanoparticle-stabilised foam requires more studies and understanding. This thesis involved the study of nanoparticle-stabilised supercritical CO2 foam in the presence of surfactant. Foams with different formulations (supercritical CO2, brine, surfactant and nanoparticles) were generated using a customised glass-bead packed column (GBPC) under 1,500 psi pressure, 25 °C, and a constant flow rate of 6 ml/min. The effect of different nanoparticle concentrations (0%, 0.1%, 0.5%, 0.6% and 1%) and brine salinities (0%, 0.5%, 2% and 10%) on foam are of the key objectives of the study and were both tested. Foam stability and foam mobility tests were carried out quantitatively and qualitatively. Pressure difference valued across the GBPC were recorded. Foam structures and formations were monitored using a camera to capture the images every three minutes throughout the duration of 60 minutes. Nanoparticle-stabilised supercritical CO2 foam successfully shows significant improvement on foam stability over surfactant foam by 27% as well as slight improvement on foam mobility reduction. Nanoparticle-stabilised foam stability in the presence of oil was also tested. Sodium dodecyl sulfate surfactant foam stabilised with 1.0 wt% nanoparticle concentration shows superior foam stability in the presence of oil.