Optimizing Middle-Phase Microemulsions for Enhanced Oil Recovery: An HLD-NAC Theoretical Framework and Experimental...

Area of Science:

• Petroleum Engineering
• Colloid and Surface Science

Background:

• Middle-phase microemulsions (Winsor III) are crucial for enhanced oil recovery (EOR) due to ultralow interfacial tension (IFT) and high oil solubilization.
• Designing effective microemulsion systems requires understanding factors like salinity and surfactant properties.

Purpose of the Study:

• To design a salinity-optimized microemulsion system using coconut oil diethanolamide (6501) for enhanced oil recovery (EOR).
• To evaluate the performance of salinity-tuned microemulsions against traditional surfactant-polymer (SP) flooding.

Main Methods:

• Utilized hydrophilic-lipophilic deviation (HLD) and net average curvature (NAC) theories for microemulsion design.
• Conducted emulsification tests and core flooding experiments to assess microemulsion performance.
• Investigated the effect of polymer on middle-phase formation and oil recovery.

Main Results:

• Increasing salinity expanded middle-phase volume, with low salinity favoring Winsor I (O/W) microemulsions.
• Polymer destabilized middle-phase formation but enhanced oil recovery by 40-45% through improved sweep efficiency.
• Traditional surfactant-polymer (SP) flooding outperformed salinity-tuned microemulsions in core flooding tests.

Conclusions:

• Salinity-tuned microemulsions offer a framework for EOR optimization, but traditional SP flooding may be more effective in certain scenarios.
• Further optimization strategies are needed for field-scale application of microemulsion-based EOR.