Effects of silica nanoparticles and polymers on foam stability with sodium dodecylbenzene sulfonate in water–liquid paraffin oil emulsions at high temperatures

Abstract The foam stability of oil–water emulsions stabilised by various surface-active components at high temperature is one of the major problems facing foam-flooding petroleum recovery because of foam instability at the high temperature underground. In this paper, foams stabilised by sodium dodecylbenzene sulfonate (SDBS), polyethylene glycol (PEG) and silica (SiO 2 ) nanoparticles in water–liquid paraffin (50%/50%) emulsions at temperature from 20 to 80 °C were studied. Foam properties such as foam stability over time at different temperatures, equilibrium surface tension, and bubble morphology (bubble size) were determined by surface tension measurements and inverted fluorescence microscopy. High foam stability was demonstrated by emulsions of SDBS, PEG, SiO 2 nanoparticles, and liquid paraffin from 40 to 80 °C. The properties of the PEG–SDBS foams improved when SiO 2 nanoparticles were added. Foam stability increased when SDBS was adsorbed on the bubble surface as the bubbles did not rupture easily in the liquid phase in the presence of SDBS because of the formation of closely packed small bubble droplets bridging between neighbouring large bubbles, which were separated by long chain polymers. This phenomenon may arise because the SiO 2 nanoparticles formed networks and were adsorbed with surfactant molecules on the bubble surface of the oil–water emulsion, causing the foam inflexibility to increase and thus improving aqueous foam stability at high temperature.