New Spectrophotometric Method for Quantitative Characterization of Density-Driven Convective Instability.

Area of Science:

• Geochemistry
• Chemical Engineering
• Environmental Science

Background:

• Carbon dioxide (CO2) convective dissolution is key for CO2 mass transfer into brine.
• Understanding CO2/brine transport is crucial for geological carbon sequestration.
• Existing methods lack real-time quantitative visualization of CO2 dissolution processes.

Purpose of the Study:

• To develop and validate a novel spectrophotometric method for characterizing CO2 convective instability.
• To enable real-time, quantitative visualization of CO2/brine transport mechanisms.
• To investigate the impact of salinity and temperature on CO2 dissolution and mass transfer.

Main Methods:

• Spectrophotometric analysis for real-time CO2 mass measurement.
• Image capture and analysis to characterize convective instability and finger development.
• Experimental study of CO2 solubility and mass transfer flux (Sherwood number).
• Comparison with theoretical calculations and numerical simulations.

Main Results:

• The new method successfully visualizes CO2 convective dissolution and measures dissolved CO2 mass.
• Convection morphologies were analyzed based on finger length and affected area.
• Experimental CO2 solubility aligns with theoretical predictions.
• Increased salinity and temperature were found to negatively impact CO2 dissolution.
• Numerical simulations qualitatively matched experimental observations.

Conclusions:

• The developed spectrophotometric method is feasible for studying CO2 convective dissolution.
• The findings improve the understanding of physical processes governing CO2 solubility trapping.
• This research provides a valuable tool for assessing CO2 sequestration efficiency.