Understanding corrosion and carbonation effects on pore scale properties of geological reservoir rocks during CO2 injection and storage: Insights from X-ray Computed Tomography

Carbon capture and storage (CCS) holds the potential to mitigate carbon dioxide (CO₂) emissions into the atmosphere. However, there is a likely accumulation of impurities generated from the corrosion reaction taking place within the pipelines during the injection process as well as during the transportation phase. Reactions can change the chemistry of injected fluids for storage, which can then react with the adjacent rock formations reservoir, affecting the reservoir porosity, permeability and caprock integrity. These are important parameters that determine the injectivity and storage capacities of deep geological sites for long term CO₂ storage. The study is aimed at evaluating the upstream corrosion of the metallic pipeline materials, correlating their kinetics with changes in the injection fluid chemistry and evaluating the effect of these combined phenomena on the storage capacities of the geological reservoir rocks. The study involves the investigation and characterisation of corrosion and bulk scaling upstream to the deep geological formations of various rock types. Reservoir rock samples are characterised before corrosion and after carbonation reactions using X-ray Computed Tomography and other micro-analytical techniques, to assess the changes in the rock storage capacity properties such as porosity, pore connectivity and permeability. Our preliminary results indicate an increase in porosity, pore size and pore connectivity in pure sandstones compared to impure sandstones, indicating that local rock chemistry in an important factor in controlling dissolution/carbonation kinetics.