The polymer microsphere has the characteristics of strong deformation ability and narrow distribution range of microsphere particles. After entering the porous medium, it has the characteristics of 'plugging macropore without  fine pore' and 'capture-deformation-migration-recapture-redeformation-remigration', which can slow down the profile reversal process and achieve the purpose of deep fluid diversion and expanding the swept volume.

The inverse microemulsion polymerization method was used to develop three systems with initial particle sizes of 50 nm, 100 nm and 300 nm, which have the advantages of good dispersion stability, narrow particle size distribution, temperature resistance, salt tolerance and shear resistance. It is suitable for low and low permeability reservoirs, and can be combined with binary / ternary composite flooding to achieve step-by-step and layer-by-layer deep profile control and flooding effect.