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Numerical simulation of carbon dioxide–nitrogen mixture dissolution in water-saturated porous media: considering cross-diffusion effects

Mahmoodpour, S ; Sharif University of Technology | 2023

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  1. Type of Document: Article
  2. DOI: 10.3390/fluids8010022
  3. Publisher: MDPI , 2023
  4. Abstract:
  5. Highlights: 1. What are the main findings? CO2–N2 mixture dissolution in brine is examined by considering the cross-diffusion effect for CO2 sequestration in a deep storage reservoir. Heterogeneity lowers the average dissolved CO2 and impedes the onset of convection. 2. What is the implication of the main finding? Correlations are developed to predict the transition time between the dissolution regimes. The possibility of impure carbon dioxide (CO2) sequestration can reduce the cost of these projects and facilitate their widespread adoption. Despite this, there are a limited number of studies that address impure CO2 sequestration aspects. In this study, we examine the convection–diffusion process of the CO2–nitrogen (N2) mixture dissolution in water-saturated porous media through numerical simulations. Cross-diffusion values, as the missing parameters in previous studies, are considered here to see the impact of N2 impurity on dissolution trapping in more realistic conditions. Homogeneous porous media are used to examine this impact without side effects from the heterogeneity, and then simulations are extended to heterogeneous porous media, which are a good representative of the real fields. Heterogeneity in the permeability field is generated with sequential Gaussian simulation. Using the averaged dissolved CO2 and dissolution fluxes for each case, we could determine the onset of different dissolution regimes and behaviors of dissolution fluxes in CO2–N2 mixture dissolution processes. The results show that there is a notable difference between the pure cases and impure cases. Additionally, a failure to recognize the changes in the diffusion matrix and cross-diffusion effects can result in significant errors in the dissolution process. At lower temperatures, the N2 impurity decreases the amount and flux of CO2 dissolution; however, at higher temperatures, sequestrating the CO2–N2 mixture would be a more reasonable choice due to enhancing the dissolution behavior and lowering the project costs. The results of the heterogeneous cases indicate that heterogeneity, in most cases, reduces the averaged dissolved CO2, and dissolution flux and impedes the onset of convection. We believe that the results of this study set a basis for future studies regarding the CO2–N2 mixture sequestration in saline aquifers. © 2023 by the authors
  6. Keywords:
  7. CO2 sequestration ; Convection–diffusion ; Dissolution trapping ; Heterogeneity ; Impurity
  8. Source: Fluids ; Volume 8, Issue 1 , 2023 ; 23115521 (ISSN)
  9. URL: https://www.mdpi.com/2311-5521/8/1/22