Experimental investigations of enhanced oil recovery using porous SiO2 aerogel nanosuspensions with emulsifying effects

To address problematic low reservoir recovery rates, a new porous SiO2 aerogel nanosuspension (NS) with emulsifying effects was developed, and its microstructure and flow characteristics were analysed with physical property and rheological tests. Moreover, macro-and microlevel flooding experiments were carried out to explore the mechanism for enhanced oil recovery (EOR). The results showed that the final recovery rates were 58.23% and 60.68% with 0.8 PV NS and NS foam slug, respectively, which were 10.03% and 13.62% higher than those of secondary oil recovery. Oil-water emulsions with different emulsification degrees were generated after sufficiently oscillating the NS and condensate oil mixture. NS flooding exhibited evident nonpiston characteristics in the early stage, and particles were transferred from water into the oil phase, which resulted in differential emulsification of the oil. The oil flow status was altered from flakes to droplets due to emulsification and the changing passage cross-section caused by particle accumulation. With NS foam flooding, the oil was first replaced by coherent large bubbles and then migrated under the effects of multiple systems. A particle circumfluence layer around the foam absorbed oil to generate an adhesive oil film.