Caprock sealing efficiency is crucial for the safety of CO 2 geological storage, with breakthrough pressure serving as a key parameter. Given the long duration of breakthrough pressure experiments on low-permeability caprock cores and the limited effectiveness of existing prediction models, this study proposes a method to calculate breakthrough pressure based on the material's critical breakthrough pore size. Using a compilation of 54 mercury intrusion porosimetry datasets from mudstone, shale, and tight sandstone, a method to determine the critical breakthrough pore size was developed. For mudstone and shale, the critical pore size is determined by subtracting the immobile water film thickness from the dominant micropore size, whereas for tight sandstone, it is defined as the pore diameter at which the non-wetting phase fully penetrates the macropores. The proposed prediction method demonstrates superior accuracy and reliability compared with existing models.
Lu et al. (Sun,) studied this question.