Change in Convection Mixing Properties with Salinity and Temperature: CO₂ Storage Application

Area of Science:

• Geochemistry
• Geophysics
• Chemical Engineering

Background:

• Geological storage of carbon dioxide (CO2) is a key strategy for climate change mitigation.
• Understanding CO2-brine interactions and fluid dynamics is crucial for efficient and safe storage.
• Density-driven convection plays a significant role in CO2 dissolution and trapping.

Purpose of the Study:

• To visualize and analyze CO2-brine convection in a Hele-Shaw cell.
• To investigate the effects of salinity and temperature on convection finger formation, migration, and mass transfer.
• To assess the implications for CO2 dissolution trapping in geological storage.

Main Methods:

• Experiments conducted in a Hele-Shaw cell simulating geological storage conditions.
• Utilized charge-coupled device (CCD) technology for direct imaging and processing of convection phenomena.
• Analyzed fluid salinity and temperature, and calculated CO2 mass fraction in brine.

Main Results:

• CO2-brine convection progresses through diffusion-dominated, convection-dominated, and shutdown stages.
• Increasing salinity accelerates finger formation and reduces onset time but suppresses finger movement.
• Convection mixing significantly enhances CO2 mass transfer, with complex temperature effects observed.

Conclusions:

• Convection mixing is a critical process for enhancing CO2 dissolution trapping in geological formations.
• Salinity and temperature are key parameters influencing the dynamics of CO2-brine convection.
• The findings aid in predicting CO2 dissolution trapping efficiency and accumulation in storage sites.