Hydrodynamics of residual oil droplet displaced by polymer solution in micro-channels of lipophilic rocks

The upper-convected Maxwell model was adopted to describe the rheological properties of polymer solutions. Then, the author established the flow equations of viscoelastic polymer solutions in pore channels and constructed a 3D flowing model of the displacing fluid. Next, the flow distribution was numerically calculated to obtain the stress distribution of the flow, the residual oil was displaced by a viscoelastic polymer solution in 3D micro-channels, and the horizontal stress difference and normal partial stress were recorded horizontal and vertical to the flow direction. Thereafter, the hydrodynamics of the residual oil displaced with a viscoelastic polymer solution was investigated from a hydrodynamic perspective. It is concluded that: the Weissenberg number has a major impact on the deformation index. As the Weissenberg number increases, the advancing angle increases while the receding angle decreases, thus pushing up the deformation index. With further increase in the Weissenberg number, the deformation index first increases linearly and then parabolically. In the research, the deformation and breakage of the residual oil in the polymer waterflooding were observed through the microscopic displacement visualization experiment, and the stress state of the residual oil in the displacement process was qualitatively analysed. With numerical simulation, this research provides fresh insights into the stress state of the residual oil in displacement.