Pore-Scale Mechanisms and Enhanced Oil Recovery Performance of Polymer-Assisted Winsor Microemulsion Systems: From...

Area of Science:

• Petroleum Engineering
• Enhanced Oil Recovery (EOR)
• Colloid and Surface Science

Background:

• Polymer flooding improves sweep efficiency but requires reduced interfacial tension for residual oil mobilization.
• Microemulsions, governed by Winsor phase conditions, enhance oil displacement through improved oil mobilization.
• Understanding pore-scale mechanisms of different Winsor phases is crucial for optimizing microemulsion flooding.

Purpose of the Study:

• To investigate the pore-scale oil displacement mechanisms of Winsor I, II, and III microemulsion systems.
• To establish a mechanistic framework linking Winsor phase behavior to oil mobilization efficiency.
• To evaluate the impact of optimized microemulsion slug design on oil recovery.

Main Methods:

• Systematic investigation using glass micromodel experiments.
• Analysis of oil detachment, emulsification, and residual oil formation for each Winsor phase.
• Evaluation of oil recovery performance for individual Winsor phases and sequential slug injections.

Main Results:

• Winsor I promoted oil detachment and emulsification; Winsor II showed limited efficiency due to viscous emulsions and columnar residual oil.
• Winsor III formed a middle-phase microemulsion, enabling solubilization-migration and effective oil mobilization.
• Winsor III achieved 81.37% recovery; optimized sequences like Winsor III-I reached 85.6% recovery.

Conclusions:

• Winsor phase behavior dictates microemulsion oil displacement mechanisms.
• Winsor III systems are most effective for oil mobilization via solubilization-migration.
• Both phase optimization and slug design are critical for maximizing microemulsion flooding performance in complex reservoirs.