Reliable estimation of CO₂–water relative permeability is essential for predicting injectivity and storage performance in saline aquifers. Yet, standard laboratory protocols are often complicated by mineral reactions and fines migration. In this study, we combine controlled coreflooding experiments, porous plate desaturation, and microscopic visualisation to evaluate how CO₂–water–rock interactions alter flow functions.

For Berea sandstone, the injection of CO₂-saturated water triggered mineral dissolution and fines mobilisation, confirmed by ICP–OES analysis (Ca²⁺, Fe³⁺, Mg²⁺ release) and SEM–EDS imaging of pore alteration and fines precipitation. These reactions produced a 21–48% reduction in CO₂ relative permeability and significant injectivity decline with increasing pore volumes of CO₂-saturated water injected. By contrast, experiments on sintered glass cores showed negligible changes, underscoring the mineralogical control. 

A porous plate method was applied to carefully desaturate cores at constant pressure, reducing water saturation in a controlled manner and enabling direct measurement of maximum CO₂ relative permeability under drainage conditions. This approach was coupled with conventional unsteady-state flooding. The porous plate desaturation technique also demonstrated that at water saturations below ~0.34, experimental limitations arise; however, it provides a more representative upper bound for CO₂ flow capacity than conventional extrapolations. Taken together, our results show that coupling visualisation with refined saturation control reveals how pore-scale reactions govern injectivity and relative permeability.

This integrated workflow advances laboratory protocols by mitigating artefacts, improving the reliability of relative permeability functions, and informing the design of CO₂ geostorage projects.