Synthesis of amphiphilic Janus SiO2/styrene butyl acrylate polymer microspheres and their application in oil recovery

We report the design and synthesis of two kinds of amphiphilic Janus SiO2 nanoparticles, including polyacrylic acid/polystyrene (PAA/PS) Janus SiO2 and polyacrylic acid/polymethylmethacrylate (PAA/PMMA) Janus SiO2. The amphiphilic Janus SiO2 nanoparticles can effectively stabilize polystyrene butyl acrylate (P(St-BA)) composite microspheres, forming low-cost oil displacing systems to improve the oil recovery of heterogeneous and low-permeability reservoirs. Among them, the PAA/PS Janus SiO2 stabilized P(St-BA) are demonstrated with good injection, migration, and plugging performance, as well as high temperature and salt resistance. These advantages enable the system an oil recovery increment of 32%. In addition, the microspheres also present good enhanced oil recovery potential in heterogeneous reservoirs, especially for cores with a permeability ratio of 2.0. In principle, the oil displacement of this system is achieved by the synergic effect of amphiphilic Janus SiO2 nanoparticles and composite microspheres. This work thus provides a promising method for high-performance yet low-cost oil recovery improvement.