Upscaling Diffusivity in CO2 Storage Processes in Deep Saline Aquifers

Unofficial AI-generated summary based on the public title and abstract. Not an official translation.

🔬研究者:The paper provides a methodology for upscaling diffusivity measurements from lab to reservoir scale, critical for accurate CCS simulation.

🏢実務担当者:Findings on grid size effects and diffusion coefficient adjustment can improve the reliability of reservoir models used in CCS project design.

🏛政策担当者:Highlights the need for continued research on CCS storage mechanisms to support safe and effective deployment.

Anthropogenic greenhouse gas (GHG) emissions, particularly carbon dioxide (CO2), have been rising drastically, contributing to climate change. One of the key potential solutions to mitigate the rising CO2 concentrations in the atmosphere is to capture and store CO2 (CCS) in underground geological formations, such as depleted oil and gas reservoirs or deep saline aquifers. Saline aquifers are considered to be important in terms of their substantial capacity for CO2 storage and their extensive availability (Bachu et al., 1994), which can play an important role in source and sink match leading to reduced transportation costs. Injection and storage of CO2 in such systems is governed by various physical and chemical processes, leading to the retention and trapping of CO2. Among the various trapping mechanisms, this paper highlights the solubility (dissolution) trapping mechanism, which is a slower process (in the context of injection time-scale) compared to structural/stratigraphic and residual trapping; however, it offers more stable and reliable storage in the time-scales aligned with the storage time. The dissolution of CO2 into the aqueous phase, followed by its mineralization into carbonate forms, enhances the permanence and the long-term security of geological storage. The formation of a denser CO2-enriched brine layer near the top of the plume induces gravitational instabilities, which promote density-driven convective fingering. This process enhances vertical mixing and accelerates CO2 dissolution into the formation brine. This study investigates the impact of grid size on CO2 dissolution, diffusion, and convection in brine using high-resolution numerical simulations based on diffusivity measurements in our laboratories. The pressure decay technique used for measurements under high pressure, temperature, and salinity conditions provided experimental data for developing a realistic model that accurately captures the effective diffusivity on dissolution in a bulk medium at a reservoir scale. A physics-based commercial simulator was utilized, with metrics including pressure, CO2 dissolution as a function of time, CO2 flux, as well as CO2 concentration at depth intervals within the brine domain. The pressure decay predicted by the model closely matched the experimental base case, validating the model and increasing confidence for the next stage of this study. The results indicate that the grid size promotes numerical averaging, influencing the evolution of the CO2 concentration within the brine domain and the morphology of the convective fingers. To mitigate the numerical effect during the process of upscaling, the diffusion coefficient must be adjusted to honor the solubility limit under specific conditions. The findings of this research offer valuable insights into the design of large-scale models and the risk mitigation of CO2 storage projects.

• semanticscholar https://doi.org/10.2118/231538-msfirst seen 2026-06-29 09:01:51