Pore-scale dynamics of multiphase reactive transport in water-wet carbonates under co₂-acidified brine injection: dissolution patterns and reaction rates
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Depleted carbonate reservoirs are promising sites for geological CO₂ storage, yet the presence of residual
hydrocarbon introduces complex pore-scale interactions that influence the dynamics of solid dissolution.
We combined time-resolved X-ray microtomography (micro-CT), core-flooding experiments, and pore-scale
modeling to investigate how residual hydrocarbon affects dissolution patterns and effective reaction rates
during CO₂ -acidified brine injection into Ketton limestone under reservoir conditions. We find that the pore structure and fluid distribution control flow heterogeneity, reactive surface accessibility, dissolution patterns and the reaction rates. At low injection rate, two distinct dissolution patterns were observed: 1) a positive
feedback loop of channel widening that efficiently enhanced transport properties; and 2) a suppressed regime in which heterogeneity and hydrocarbon blockage resulted in only a modest increase in permeability. At high injection rates, a more uniform dissolution occurred caused by re-mobilization of hydrocarbon that initially blocked the flow of brine. Effective reaction rates in two-phase flow were lower than in the equivalent single phase case and up to two orders of magnitude lower than the batch rates due to persistent transport limitations. These findings provide mechanistic insights into multiphase reactive transport in carbonates and highlight the importance of accurately understanding the impact of the residual phase on reactions to improve predictions
of CO₂ storage efficiency.
hydrocarbon introduces complex pore-scale interactions that influence the dynamics of solid dissolution.
We combined time-resolved X-ray microtomography (micro-CT), core-flooding experiments, and pore-scale
modeling to investigate how residual hydrocarbon affects dissolution patterns and effective reaction rates
during CO₂ -acidified brine injection into Ketton limestone under reservoir conditions. We find that the pore structure and fluid distribution control flow heterogeneity, reactive surface accessibility, dissolution patterns and the reaction rates. At low injection rate, two distinct dissolution patterns were observed: 1) a positive
feedback loop of channel widening that efficiently enhanced transport properties; and 2) a suppressed regime in which heterogeneity and hydrocarbon blockage resulted in only a modest increase in permeability. At high injection rates, a more uniform dissolution occurred caused by re-mobilization of hydrocarbon that initially blocked the flow of brine. Effective reaction rates in two-phase flow were lower than in the equivalent single phase case and up to two orders of magnitude lower than the batch rates due to persistent transport limitations. These findings provide mechanistic insights into multiphase reactive transport in carbonates and highlight the importance of accurately understanding the impact of the residual phase on reactions to improve predictions
of CO₂ storage efficiency.
Date Issued
2026-02-01
Date Acceptance
2025-12-26
Citation
Advances in Water Resources, 2026, 208
ISSN
0309-1708
Publisher
Elsevier BV
Journal / Book Title
Advances in Water Resources
Volume
208
Copyright Statement
© 2025 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
License URL
Publication Status
Published
Article Number
105202
Date Publish Online
2026-01-05