Micro-CT-based pore-network analysis of carbonate rock dissolution: Linking microstructural evolution to permeability enhancement

Understanding how carbonate rock microstructure evolves during dissolution is essential for optimizing acid stimulation and assessing the integrity of carbon dioxide storage reservoirs. In this study, four carbonate core samples subjected to hydrochloric acid flooding were analyzed using micro-computed tomography and pore-network modeling to quantify changes in pore geometry and transport properties. Three-dimensional digital reconstructions of pre- and post-dissolution volumes revealed significant restructuring of the pore system, including the coalescence of small pores and the formation of new flow channels. Quantitative analysis showed that the mean pore and throat radii increased substantially, accompanied by a marked rise in connected porosity. These morphological changes led to a substantial enhancement in absolute permeability, while hydraulic tortuosity generally decreased. The extent of microstructural restructuring varied markedly among the analyzed sub-samples, reflecting differences in their initial pore architecture and dissolution patterns. Changes in pore-network topology and throat connectivity exerted a stronger control on permeability than uniform pore-size enlargement alone. Higher injection rates promoted the formation of localized preferential flow pathways by enhancing advective transport, which strongly influenced the resulting permeability evolution. The results highlight the critical role of dissolution heterogeneity and injection rate in controlling permeability evolution, providing pore-scale insights. The results provide pore-scale insights primarily applicable to carbonate acidizing processes, while also offering qualitative implications for carbon dioxide-brine – carbonate systems. Document Type: Original article Cited as: Bolysbek, D. A., Kuljabekov, A. B., Uzbekaliyev, K. Sh., Assilbekov, B. K. Micro-CT-based pore-network analysis of carbonate rock dissolution: Linking microstructural evolution to permeability enhancement. Capillarity, 2026, 18(3): 96-105. https://doi.org/10.46690/capi.2026.03.02