Figures 4 and 5 show residual oil distribution images after viscoelastic polymer and glycerin flooding, respectively, where the dark shade is oil and the light shade is the displacement fluid.
The displacement fluid includes AP-P4 hydrophobically associating water-soluble polymers and glycerin solutions, where the viscosity of both fluids was 40 mPa x s at 65[degrees]C, and the particulates and agglomerates were filtered by a sand core funnel of G1 type with apertures of 20~30 [micro]m from the solutions.
Flow Oil Incremental rate recovery oil recovery Displacement fluid (PV/h) (%) by elasticity (%) Glycerin solution 1.0 50.0 -- Viscoelastic polymer 56.0 6.0 solution Table 2: Displacement efficiency of glycerin and viscoelastic polymer with the same viscosity (40 mPa x s) at different water displacement sweep efficiency levels.
further conducted many studies and carried out glycerin and polymer solutions displacement of residual oil in dead ends, using the same viscosity for both displacement fluids, the results of which showed that an elastic polymer can reduce the residual oil saturation more than glycerin flooding and that a polymer solution can exhibit a "pull" and "tripping" on an oil blank and oil droplet [52, 53].
After that, the micromodel experiments with different elastic displacement fluids were performed in different degrees of water flooding, and the role of viscoelasticity in polymer flooding process was worked out.
The displacement fluids include brine, glycerin, and AP-P4 hydrophobically associating water-soluble polymers with a relative molecular weight of 1.1 x [10.sup.7] Da.
We investigated polymer and glycerin displacement medium viscosity oil, in which the viscosity of both displacement fluids is 40 mPa x s.
Based on the microvisual experiments, the core flooding experiments were further carried out, and the understanding on the viscoelastic behavior of polymer flooding in medium viscosity oil recovery were validated, where the displacement fluids were also glycerin and polymer solutions of the same viscosity.
And polymer has the ability of increasing the viscosity of displacement fluid. Even though the ASP flooding increases the oil production compared to the water flooding techniques, it is faced with new problems.
At the same time, the absorption peak of carboxylic acid at 1576 [cm.sup.-1] has been found in the displacement fluid of the compound system.