Preparation of styrene‐phenylamine monomer copolymer nanospheres and its performance for stabilizing <scp>CO₂</scp> foam

Abstract Improving the stability of CO 2 foam is a core concern in CO 2 foam flooding oil recovery technology. Using hydrophobic nano‐SiO 2 to enhance the stability of CO 2 foam is a common approach, but hydrophobic nano‐SiO 2 faces challenges, such as easy aggregation, difficult dispersion, and performance needs to improve. In this article, a novel dispersion of styrene‐phenylamine monomer copolymer (PSSN) nanosphere with primary amine groups on the surface was synthesized. The synthesis conditions of PSSN were optimized, and its performance for stabilizing CO 2 foam was evaluated. The experimental results demonstrated that PSSN had better performance for stabilizing CO 2 foam than that of hydrophobic nano‐SiO 2 when using cocamidopropyl betaine (CAB) as the foaming agent. With the CAB concentration of 4000 mg/L and PSSN concentration of 100 mg/L in the brine having salinity of 8460 mg/L, the half‐life of CO 2 foam at 90°C was 131 min, which was 43 min longer than that stabilized by hydrophobic nano‐SiO 2 under the same conditions. This is for the first time that polystyrene microspheres with amine groups on the surface was used to stabilize CO 2 foam. The study provides a new nanoparticle option for stabilizing CO 2 foam.