Carbon Capture and Storage (CCS) is a solution to mitigate emissions from large-scale fossil energy and industrial sources. However, widespread implementation hinges on overcoming significant challenges. The global landscape of CCS has experienced notable growth in the past five years, driven by private sector response to public demands for a transition to a net-zero emissions future, as well as shifts in government policies and increased investments worldwide. For many regions, particularly in Europe, offshore storage emerges as the preferred choice, with transportation by ship offering compelling advantages, including reduced capital expenditure, lower financial risk, and heightened flexibility. A critical aspect of ship-based CO2 transport is the extremely low temperature required (-53°C at 7 bar) to maintain it in a liquid state. Injecting such a cold fluid into a reservoir with temperatures typically between 70°C and 200°C raises serious challenges, particularly for ensuring the well integrity, notably its main sealing element—the cement sheath. Identified risks include casing debonding, thermal fracturing, and the potential formation of CO2 hydrates and ice within the reservoir rock, cement, or caprock. The current project is dedicated to advancing the understanding and conducting a quantitative analysis of wellbore integrity during cold CO2 injection into a high-temperature reservoir. A multidisciplinary and multi-scale research program covering various methods and tools has been established. These range from thermodynamics and molecular dynamics simulations addressing CO2 hydrate formation to laboratory experiments characterizing casing/cement/rock interfaces, along with developing a laboratory-scale physical model of the well structure and numerical simulations at the wellbore scale.