The Experimental Study on Relative Permeability Hysteresis in CO₂‑Enhanced Oil Recovery and Sequestration Processes.

Area of Science:

• Petroleum Engineering
• Geosciences
• Chemical Engineering

Background:

• Relative permeability hysteresis significantly impacts CO2 sequestration and enhanced oil recovery (EOR).
• Previous studies identified factors like pressure, core permeability, and saturation paths influencing hysteresis.
• A systematic, integrated analysis of multiple factors affecting hysteresis is currently lacking.

Purpose of the Study:

• To investigate the complex mechanisms of relative permeability hysteresis under various conditions.
• To provide comprehensive solutions for CO2 sequestration and EOR by analyzing multiple influencing factors.
• To address the gap in systematic research methodology for hysteresis analysis.

Main Methods:

• Conducted CO2-water two-phase and CO2-oil-water three-phase relative permeability experiments.
• Systematically varied parameters including temperature, pressure, core permeability, displacement cycles, and saturation history.
• Analyzed the impact of these variables on fluid flow characteristics and hysteresis.

Main Results:

• In CO2-water systems, reduced permeability and pressure decreased coflow interval and endpoint permeability, increasing trapped gas saturation.
• Low-permeability cores showed increased trapped gas with decreasing pressure; high-permeability cores were less affected.
• Reduced permeability and pressure in CO2-oil-water systems decreased coflow interval, endpoint permeability, and oil recovery.

Conclusions:

• Findings provide critical insights into relative permeability hysteresis for CO2-enhanced oil recovery and sequestration.
• The study offers guidance for optimizing injection and production strategies in Carbon Capture, Utilization, and Storage (CCUS) projects.
• Understanding hysteresis effects is vital for improving the efficiency and effectiveness of EOR and CO2 storage operations.