Study on Micro Production Mechanism of Corner Residual Oil after Polymer Flooding

Abstract

To study the microscopic production mechanism of corner residual oil after polymer flooding, microscopic visualization oil displacement technology and COMSOL finite element numerical simulation methods were used. The influence of the viscosity and interfacial tension of the oil displacement system after polymer flooding on the movement mechanism of the corner residual oil was studied. The results show that by increasing the viscosity of the polymer, a portion of the microscopic remaining oil in the corner of the oil-wet property can be moved whereas that in the corner of the water-wet property cannot be moved at all. To move the microscopic remaining oil in the corners with water-wet properties after polymer flooding, the viscosity of the displacement fluid or the displacement speed must be increased by 100–1000 times. Decreasing the interfacial tension of the oil displacement system changed the wettability of the corner residual oil, thus increasing the wetting angle. When the interfacial tension level reached 10−2 mN/m, the degree of movement of the remaining oil in the corner reached a maximum. If the interfacial tension is reduced, the degree of production of the residual oil in the corner does not change significantly. The microscopic production mechanism of the corner residual oil after polymer flooding expands the scope of the displacement streamlines in the corner.

Microscopic Remaining Oil Distribution Regularity and Enhanced Oil Recovery Methods after Polymer Flooding

“…The tableting process had to be conducted under low-temperature freezing conditions, which did not affect the test results. After the frozen core grinding slice, it maintained the initial condition of oil–water distribution, and sheet thickness was 0.04–0.05 mm which could avoid particle fluctuation and fluorescence interference. , Through confocal laser scanning microscope scanning oil wafer sample with three-dimensional, we identified the properties of minerals and oil–water boundaries because the oil, water, and minerals have different fluorescent characters, intensities, and colors. Using self-developed analysis software, the occurrence phases of microscopic remaining oil were studied accurately, which demonstrated the distribution characteristics of microscopic remaining oil.…”

Recent Advances in Polymer Flooding in China

“…However, the displaced residual oil is more likely to be displaced by mechanisms other than the believed viscoelasticity effect. Sun et al [ 66 ] performed experiments using both water and oil wet pores. For water wet pore models, which were similar to those in [ 32 ], the viscoelasticity effect did not appear to affect the dead-end residual oil [ 66 ].…”

“…Sun et al [ 66 ] performed experiments using both water and oil wet pores. For water wet pore models, which were similar to those in [ 32 ], the viscoelasticity effect did not appear to affect the dead-end residual oil [ 66 ]. In this reference, a significant increase in the viscosity of polymers was observed, which typically corresponds to an increase in viscoelasticity according to previous studies.…”