Formulation of Polymer-Augmented Surfactant-Based Oil-Water Microemulsions for Application in Enhanced Oil Recovery.

Area of Science:

• Petroleum Engineering
• Colloid and Surface Science
• Materials Science

Background:

• Conventional surfactant-stabilized emulsions lack stability and effective wettability alteration for enhanced oil recovery (EOR).
• Phase instability and limited temperature resilience hinder the efficiency of traditional chemical EOR methods.
• Optimizing interfacial properties is crucial for maximizing oil displacement in porous media.

Purpose of the Study:

• To develop and evaluate polymer-surfactant microemulsions for enhanced stability and improved interfacial properties in EOR.
• To investigate the impact of polymer addition on microemulsion viscosity, phase behavior, and temperature resilience.
• To assess the wettability alteration and oil recovery efficiency of the engineered microemulsions in sandstone cores.

Main Methods:

• Formulation of oil-water microemulsions using synergistic polymer and surfactant combinations.
• Characterization of microemulsion stability, interfacial tension (IFT) across varying salinities and temperatures.
• Rheological measurements (viscosity) and zeta potential analysis to confirm emulsion stability.
• Core flooding experiments to evaluate additional oil recovery compared to conventional water flooding.

Main Results:

• Polymer-augmented microemulsions exhibited significantly enhanced viscosity (300 mPa·s vs. 50 mPa·s) and improved phase stability.
• Optimal oil-microemulsion IFT of 4.43 × 10^-4 mN/m achieved at balanced salinity.
• Microemulsions demonstrated stability across a range of temperatures, transitioning between Winsor II and III phases.
• Core flooding showed an additional 20.58% oil recovery using the engineered microemulsions.

Conclusions:

• Synergistic polymer-surfactant systems create robust microemulsions for effective EOR.
• Enhanced viscosity and stability of microemulsions improve sweep efficiency and oil displacement.
• Engineered microemulsions successfully alter sandstone wettability, leading to significant increases in oil recovery.