Simulation of bench-scale CO₂ injection using a coupled continuum-discrete approach.

Area of Science:

• Geosciences
• Environmental Science
• Chemical Engineering

Background:

• Carbon capture and storage (CCS) operations carry risks of unintended CO2 releases, potentially impacting atmospheric and water resources.
• Predictive tools are crucial for assessing CO2 migration pathways and groundwater impacts from such releases.
• Conventional multiphase flow models face challenges in simulating discontinuous flow characteristic of leakage sites.

Purpose of the Study:

• To evaluate the efficacy of a coupled continuum-discrete model, ET-MIP, in simulating CO2 migration from a bench-scale injection.
• To assess the model's ability to capture complex phenomena like gas fingering and multicomponent mass transfer.
• To investigate the sensitivity of CO2 subsurface migration to mass transfer processes.

Main Methods:

• Application of the ET-MIP (Environmental Transport - Multiphase Isotope and Flow) model for a bench-scale CO2 injection experiment.
• Simulation of discontinuous gas flow and multicomponent mass transfer.
• Analysis of simulation efficiency and sensitivity to various subsurface conditions.

Main Results:

• ET-MIP accurately captured gas fingering behavior and complex multicomponent mass transfer.
• Simulations were computationally efficient, enabling multiple displacement pressure realizations.
• CO2 migration was found to be sensitive to mass transfer, influenced by groundwater velocity and background dissolved gases.

Conclusions:

• The ET-MIP model provides a computationally efficient and accurate tool for simulating CO2 migration in subsurface environments.
• Mass transfer significantly influences CO2 migration pathways, dissolution, and persistence, suggesting monitoring of low-solubility gases may be advantageous.
• Findings are relevant for assessing risks associated with various subsurface gas migrations, including hydrogen and methane from geoenergy wells.