Speaker
Description
Understanding reactive microscale flows in porous media is essential for managing the geochemical processes involved in subsurface $CO_2$ storage. These processes, including precipitation, crystallization, and dissolution, contribute to the mineral trapping of injected CO2 and govern the evolution of fluid-mineral interfaces. Bridging these pore-scale phenomena with their large-scale implications is critical for assessing storage capacity and ensuring reservoir integrity, thereby facilitating effective risk management of CO2 storage sites.
This work explores the numerical simulation of precipitation and crystallization in realistic porous media geometries obtained by X-ray microtomography. By coupling superficial velocity models with a Lagrangian formulation of the chemistry, the method achieves a high degree of efficiency and accuracy in simulating reactive flows at the pore scale.
We introduce a two-step crystallization model for $CO_2$ mineral trapping, which includes the primary homogeneous nucleation of the dissolved chemical species and crystal growth driven by interactions with the solid interface. The model incorporates a probabilistic reaction rate for the crystal growth, accounting for the geometrical dependency in the aggregation of the precipitate at the interfaces. This approach enables the investigation of flow path restructuring caused by partial or complete clogging of pore throats. This will ultimately impact the prediction of flow and transport in $CO_2$ storage reservoirs.
Numerical simulations reveal distinct clogging and non-clogging regimes, highlighting the importance of both geometrical features and flow parameters in pore-scale mineral trapping. To further characterize these phenomena, we propose an additional dimensionless number that contributes to the identification of clogging patterns based on the adsorption frequency of the precipitates to the mineral interface. Finally, the impact of these microscale interfacial phenomena on macroscale porosity and permeability is investigated across different regimes, with comparisons between clogging and non-clogging configurations.
| Country | United Kingdom |
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