Effective geological carbon dioxide (CO 2 ) sequestration depends not only on injection operations but also on strategic storage site selection that ensures long-term containment and injectivity. This study evaluates CO 2 storage potential in the Hardeman Basin, Texas, through a dual-framework comparison of two site selection strategies: a source-driven approach prioritizing proximity to emission sources (scenario A) and a reservoir-driven approach emphasizing reservoir quality and injectivity (scenario B). Dynamic compositional simulations using CMG GEM were performed on 3D geological models to assess CO 2 plume migration, pressure evolution, injectivity, and trapping efficiency under single- and multi-well injection scenarios. Results obtained from the study indicate that the reservoir-driven strategy consistently outperforms the source-driven approach, demonstrating higher sustained injectivity, improved pressure management, and more favorable CO 2 trapping mechanisms. While Scenario A benefits from reduced transport distance, the reservoirs in this category exhibit earlier pressure constraints and limited storage efficiency due to suboptimal reservoir properties. In contrast, the reservoirs in Scenario B enable larger storage volumes and enhanced long-term containment, even when located farther from emission sources. This study highlights the trade-off between logistical convenience and storage performance and demonstrates that reservoir quality is a dominant control on CCS viability. The proposed comparative framework provides a practical and transferable methodology for screening and prioritizing CO 2 storage sites in structurally complex basins—such as the Hardeman Basin—thereby supporting more resilient, scalable, and performance-driven CCS deployment strategies.
Understanding gas adsorption in organic-rich shales is critical for evaluating their role in CO 2 sequestration and underground hydrogen storage. In this study, grand canonical Monte Carlo (GCMC) simulations were performed to investigate the adsorption behavior of carbon dioxide (CO 2 ), methane (CH 4 ), and hydrogen (H 2 ) on Type II kerogen at two maturity levels (immature II-A and post-mature II-D) under both dry and moisture-rich conditions. Results show that CO 2 consistently exhibits the strongest adsorption due to its quadrupole moment and interaction with heteroatom functional groups, followed by CH 4 , while H 2 shows the weakest affinity governed by van der Waals forces. Kerogen maturity significantly enhances adsorption, with II-D outperforming II-A due to greater aromaticity and micropore volume. However, pre-adsorbed water sharply reduces adsorption of all gases by occupying polar sites and clustering within pores. Moisture reduces CO 2 capacity by >98%, nearly eliminates CH 4 uptake, and suppresses H 2 to trace levels. Despite these reductions, moisture increases CO 2 /CH 4 and CO 2 /H 2 selectivity, as CO 2 retains minimal residual adsorption while CH 4 and H 2 is almost completely excluded. These findings highlight the role of kerogen maturity and moisture in controlling gas storage, with key implications for optimizing CO 2 sequestration and assessing the feasibility of shale formations for H 2 storage.
