Ensuring legacy wells containment as part of CO2 storage projects is continuous industry challenge, where applying the regulative requirements and industry guidelines with project experience has allowed projects to be realized. In CO2 storage projects, legacy wells, either from exploration or production activities from Oil and Gas operations are commonly exist, presenting integrity questions towards zonal isolation and leakage potential. These boreholes are important to validate and provide a clear rationale and evidence towards integrity in order to validate the containment of the CO2 storage complex. Operators and consultants have developed different methods, practices and risk tools in order to identify key risks and eventually validate projects for CO2 storage. Experience from case studies, where quantitative and qualitative methods have been used to systematically analyze the legacy wells is shared as well as key learnings, opportunities and solutions for projects to come.