Electromigration effects on subsurface ionic transport: Numerical modeling and its implications for geological carbon storage

Reactive transport modeling is essential for the analysis and description of modern surface energy systems. Applications such as geological carbon storage and geothermal energy production often involve ionic species in transport processes and chemical reactions. However, current modeling frequently neglects the electromigration effect, which can significantly influence ionic transport. In this dissertation, a computational framework is developed to incorporate electromigration effects into reactive transport modeling, with a particular focus on its application in geological carbon storage. Major effects include the Coulomb effects due to electroneutral diffusive flux and electrical double layer effects in charged nanopores are investigated. For Coulomb effects, the electroneutral Nernst–Planck formulation is employed. Despite its successful application, this formulation lacks a rigorous theoretical basis and introduces great numerical complexity. Therefore, a novel dimensionless number is proposed to quantify its deviation from traditional Fickian diffusion, and thermodynamic consistency is proved through the analysis of the extended diffusion coefficient matrix. To address computational challenges, a numerical scheme that ensures stability and maintains linear efficiency is proposed. discussing both temporal and spatial discretization strategies. With the proposed scheme, numerical results considering Coulomb effects show distinct deviations from current simulations in convective dissolution modeling. For electrical double layer effects, a linear, unconditionally energy-stable numerical scheme for the Poisson-Nernst-Planck equations is proposed. This scheme, derived from a gradient-flow formulation and energy factorization approach, offers a promising method for simulating complex transport phenomena in charged systems. By integrating this scheme with the conventional reactive transport model, the impact of the electrical double layer on transport processes associated with geological carbon storage is examined at the pore scale.


ErSE Ph.D Candidate Tian Qiao, Supervised by Prof. Shuyu Sun

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08 Sep, 2024
04:00 PM - 05:00 PM
Al-Jazri Building (Bldg. 4), Room 5220