A semi-Lagrangian method for the direct numerical simulation of crystallization and precipitation at the pore scale

2024-09-09

Frontiers in Earth Science

AI Summary

This study addresses the poorly understood pore-scale clogging mechanisms induced by crystallization/precipitation in mineral CO₂ sequestration. We propose a direct numerical simulation method embedded within real rock pore structures reconstructed from X-ray computed tomography (CT). Methodologically, we pioneer the incorporation of adsorption kinetics into a semi-Lagrangian particle framework, coupling a porous-medium apparent velocity model with a Lagrangian chemical reaction description based on transition state theory—enabling unified modeling of both crystallization and precipitation. We innovatively define a dimensionless number characterizing the bistable transition between clogged and unclogged states and quantitatively identify its critical threshold. The simulations successfully reproduce the evolution of pore clogging induced by mineral precipitation during CO₂ mineralization, providing a computationally tractable, pore-scale mechanistic model for predicting storage efficiency and long-term stability.

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Abstract

This article introduces a new efficient particle method for the numerical simulation of crystallization and precipitation at the pore scale of real rock geometries extracted by X-Ray tomography. It is based on the coupling between superficial velocity models of porous media, Lagrangian description of chemistry using Transition-State-Theory, involving underlying grids. Its ability to successfully compute dissolution process has been established in the past, and is presently generalized to precipitation and crystallization by means of adsorption modeling. Numerical simulations of mineral CO2 trapping are provided, showing evidence of clogging/non-clogging regimes, and one of the main results is the introduction of a new non-dimensional number needed for this characterization.

Problem

• Simulates crystallization and precipitation at pore scale.
• Couples porous media velocity with chemical reactions.
• Introduces non-dimensional number for clogging characterization.

Innovation

• Semi-Lagrangian method for pore-scale simulation
• Coupling velocity models with Transition-State-Theory
• Adsorption modeling for precipitation and crystallization