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Description
Carbon dioxide sequestration in post-burn Underground Coal Gasification (UCG) cavities is a complex process involving disparate flow regimes. To accurately capture the physics of CO2 injection into a water-saturated cavity, this study constructs a sophisticated multi-region geometric model considering both the open-void space and the surrounding porous boundaries.
We implement a comprehensive mathematical framework where fluid dynamics are governed by the Brinkman equations, bridging the gap between free flow and seepage. The model incorporates Henry’s Law for phase equilibrium and an advection-diffusion system for component transport. A fully implicit, monolithic solver based on the Finite Element Method (FEM) is employed to ensure numerical stability and handle the strong non-linear coupling of the physical fields.
Our research highlights that the CO2 injection process is not a simple displacement but a structured evolution governed by specific hydrodynamic mechanisms. We systematically classify the injection process into three distinct evolutionary stages: Pre-vortex Momentum Accumulation Stage, characterized by the formation of an asymmetric momentum reservoir and boundary-induced velocity gradients; Stagnation-Induced Redirection Stage, where the conversion of kinetic energy into a stagnation pressure field dictates the plume's trajectory; Structural Maturation Stage, involving the formation of a nested dissipative structure that enables stable CO2 trapping.
By characterizing these transitions, this work offers a theoretical framework for understanding fluid distribution in large-scale underground openings. The proposed modeling approach and the identified mechanism stages provide critical insights for optimizing injection protocols and assessing the long-term stability of CO2 storage in UCG cavities.
| Country | China |
|---|---|
| Green Housing & Porous Media Focused Abstracts | This abstract is related to Green Housing |
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