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oa Comparative Hydrogeochemical Analysis of Opalinus Clay’s Lithofacies to CO2 Injection Using HYTEC
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, World CCUS Conference 2025, Sep 2025, Volume 2025, p.1 - 5
Abstract
The integrity of caprock formations is crucial for secure CO2 storage. This study employs HYTEC reactive transport code to assess the hydrogeochemical responses of Opalinus Clay lithofacies—shaly, sandy, and carbonate-rich sandy—under CO2 injection, based on the CO2LPIE experiment at Mont Terri. Results reveal that lithofacies composition governs geochemical reactivity, with carbonate-rich sandy facies showing significant carbonate dissolution and re-precipitation, while shaly facies remains stable, reinforcing its caprock potential. Sandy facies exhibits intermediate behaviour. High hydraulic conductivity combined with high carbonates initial content leads to further CO2 penetration and pH perturbation in carbonate facies. These findings emphasize the need for lithofacies-specific assessments in CO2 storage, providing geochemical insights for developing THMC models to evaluate caprock integrity.