Formation Damage During CO2 Storage: Analytical Model, Field Cases

This study develops analytical models and explicit formulae to characterize well injectivity and reservoir behavior during CO2 injection in layer-cake aquifers and depleted gas fields, while considering formation damage. The methodology involves deriving 2-phase flow equations incorporating permeability damage mechanisms and upscaling. While formation damage reduces injectivity, in situ permeability decreases in swept areas redirect gas to unswept zones, enhancing storage capacity. The developed models are also applied to three real reservoirs—A, B, and C located in the formation L in Malaysia. The results indicate that as the damage factor d transitions from 1, representing a damage-free reservoir, to the critical value dc where the well impedance remains constant during injection, there is a notable increase in sweep efficiency for reservoir A, rising from 3% to 53%. Similarly, in the case of reservoir B, the sweep shows a significant increase from 7% to 50%. Additionally, for reservoir C, the sweep undergoes a substantial rise from 1% to 52%. The study introduces explicit formulae reflecting these processes and contributes novel insights by creating a fast-analytical tool, providing a valuable addition to understanding CO2 injection processes in diverse geological settings.