A numerical analysis of background flow velocity effects on long-term post-injection migration of CO2 plumes in tilted storage aquifers

Mawda Awag*, Eric Mackay, Saeed Ghanbari

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Even though groundwater flow exists in many saline aquifers, very few studies have investigated its significance on the injected CO2 migration and trapping processes. Here, a numerical simulation approach is used to study the late post-injection migration and trapping of CO2 injected into a tilted aquifer. The analysis highlights that although the migration of the CO2 and its dissolution in brine is induced by buoyancy, the existence of background flow can further affect the plume velocity, convective dissolution, the dissolved CO2 flux and its distribution in the storage complex. Our analysis shows that the background flow removes the residual CO2, by dissolution, before the convective dissolution of the mobile part becomes dominant. The plume decelerates during its vertical migration by a factor of 6.5; then, its height increases with time to more than 15% as background flow velocity increases, hence reducing its rate of deceleration. However, when the plume reaches its maximum height, it migrates with a constant velocity. Greater background flow velocity not only allows the plume to migrate further, but it may hinder CO2 dissolution. This is because it can transport the dissolved CO2 underneath the plume for a long time, thus slowing down the interaction at the CO2-brine interface. The weak and strong background flows can impact the tendency of the dissolved CO2 to persist underneath the caprock. Our results indicate the existence of a critical background flow velocity which can control the distribution of the dissolved CO2 at the bottom of the aquifer, further away from the caprock.

Original languageEnglish
Pages (from-to)103-114
Number of pages12
JournalAdvances in Geo-Energy Research
Volume11
Issue number2
Early online date24 Dec 2023
DOIs
Publication statusPublished - Feb 2024

Keywords

  • background flow velocity
  • CO plume migration
  • plume distribution
  • plume instantaneous velocity
  • tilted aquifer

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Geotechnical Engineering and Engineering Geology
  • Mechanics of Materials

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