Molecular-scale insights into nanoconfined water-CO2 interactions in geological carbon storage.

• Molecular modelling of complex nanoconfined water-CO 2 interactions in porous media. • In-depth analyses of water film and water bridge's generation and evolution. • Implications for complex nanoconfined water-CO 2 dynamics and geological carbon storage and utilization. Understanding the nanoconfined water-CO 2 interactions at the molecular scale is of great importance for the fluid transport in confined porous media. Here, a series typical water film and water bridge scenarios are determined, and the associated impacts on nanoconfined water-CO 2 interactions as well as the geological hydrocarbon recovery and CO 2 storage are investigated in nanopores. Our results confirm either in water film or water bridge scenarios, the competitive adsorptions of nanoconfined water and CO 2 reduce the adsorbed water amount and derive the new water bridge with CO 2 additions. Such a phenomenon indicates the substrate surface shifts from water-wet to partially CO 2 -wet, with lower fluid molecule diffusions and illite-water-CO 2 sandwich-structured adsorption layer. Overall, our work investigates the mechanism of CO 2 effects on distributions and aggregations of nanoconfined water molecules in nanopores, which also provides molecular-scale insights into the nanoconfined water-CO 2 interactions in the processes of geological CO 2 storage and utilization. [ABSTRACT FROM AUTHOR]