Open Access

ARTICLE

Numerical Modelling of CO₂ Plume Evolution and Dissolution in a Stratified Saline Aquifer

Bohao Wu^*, Xiuqi Zhang, Haoheng Liu, Yulong Ji

Marine Engineering College, Dalian Maritime University, Dalian, 116026, China

* Corresponding Author: Bohao Wu. Email:

(This article belongs to the Special Issue: Multiphase Fluid Flow Behaviors in Oil, Gas, Water, and Solid Systems during CCUS Processes in Hydrocarbon Reservoirs)

Fluid Dynamics & Materials Processing 2025, 21(10), 2359-2387. https://doi.org/10.32604/fdmp.2025.067651

Received 08 May 2025; Accepted 29 July 2025; Issue published 30 October 2025

Abstract

Geological sequestration of carbon dioxide (CO₂) entails the long-term storage of captured emissions from CCUS (Carbon Capture, Utilization, and Storage) facilities in deep saline aquifers to mitigate greenhouse gas accumulation. Among various trapping mechanisms, dissolution trapping is particularly effective in enhancing storage security. However, the stratified structure of saline aquifers plays a crucial role in controlling the efficiency of CO₂ dissolution into the resident brine. In this study, a two-dimensional numerical model of a stratified saline aquifer is developed, integrating both two-phase flow and mass transfer dynamics. The model captures the temporal evolution of gas saturation, reservoir pressure, and CO₂ dissolution behavior under varying geological and operational conditions. Specifically, the effects of porosity heterogeneity, permeability distribution, and injection rate on the dissolution process are examined, and sequestration efficiencies across distinct stratigraphic layers are compared. Simulation results reveal that in the early phase of CO₂ injection, the plume spreads radially along the lower portion of the aquifer. With continued injection, high-saturation regions expand upward and eventually accumulate beneath the shale and caprock layers. Pressure within the reservoir rises in response to CO₂ injection, propagating both vertically and laterally. CO₂ migration and dissolution are strongly influenced by reservoir properties, with progressive dissolution occurring in the pore spaces of individual layers. High-porosity zones favor CO₂ accumulation and enhance local dissolution, whereas low-porosity regions facilitate vertical diffusion. An increase in porosity from 0.25 to 0.30 reduces the radial extent of dissolution in the high-permeability layer by 16.5%. Likewise, increasing permeability promotes radial dispersion; each 10 mD increment extends the CO₂ dissolution front by approximately 18 m. Elevated injection rates intensify both vertical and lateral plume migration: every 0.25 × 10⁻⁶ m/s increase in rate yields an average 100–120 m increase in radial dissolution distance within high-permeability zones.

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