Speaker
Description
Coupled mineral dissolution, precipitation, and gas exsolution are critical in subsurface energy applications such as natural hydrogen extraction, nuclear waste storage, and CO2 sequestration. However, the behavior of exsolved gases in rock matrices remains poorly understood, particularly regarding whether gases become trapped by precipitates, induce pore clogging, or migrate with fluid flow and dissolve downstream. These uncertainties hinder the accuracy of reactive transport models for long-term predictions. To address this, we conducted microfluidic experiments using a model system based on witherite dissolution, barite precipitation, and CO2 exsolution to identify the conditions under which gas is produced and their in these systems. Microfluidic experiments, combined with in situ Raman spectroscopy and geochemical modeling, revealed that CO2 bubbles formed during dissolution serve as nucleation sites for barite. CO2 bubbles became enclosed by precipitates when the barite crystallization rate exceeded the CO2 production rate, a process controlled by the acidity of the solution and the solution's saturation with respect to barite. These were followed by core-scale experiments to investigate whether the gases produced during the reactions are trapped or transported in the porous media. Magnetic Resonance Imaging (MRI) was used to monitor heterogeneous gas production, transport, and relative gas content in porous media over time. These results were complemented by measurements of pH, pCO2, differential pressure, and effluent ion concentrations. Scanning electron microscopy showed porosity reduction due to barite precipitation and localized clogging at bubble surfaces. Our experiments highlight key areas requiring further investigation, as current empirical models like Van Genuchten-Mualem and Brooks-Corey fail to account for chemical reactions that alter pore geometry, connectivity, and wettability. While reactive transport modeling addresses multi-phase flows and mineral reactions, existing codes like TOUGHREACT and PFLOTRAN lack the ability to fully couple precipitation, dissolution, and gas dynamics. Advanced mathematical coupling approaches and refined porosity-permeability models are essential for accurately simulating the interplay of these processes, especially under conditions involving gas generation and transport.
| Country | Germany |
|---|---|
| Water & Porous Media Focused Abstracts | This abstract is related to Water |
| Acceptance of the Terms & Conditions | Click here to agree |
