a b s t r a c t CO 2 injection for storage in subsurface geologic medium is one of the techniques developed in the past years to mitigate anthropological CO 2 . Prior to CO 2 injection, it is essential to predict the feasibility of medium in terms of storage capacity, injectivity, trapping mechanisms, and containment. There have been many studies regarding techniques which can be applied to ensure the safety of CO 2 injection. However, there are few studies indicating the importance of capillary trapping during and after CO 2 injection. The aim of this study is to review the fundamentals of injectivity and its relationship with capillary trapping for CO 2 storage in depleted oil and gas reservoirs. Considering the number of effective parameters which are associated with the injectivity and capillary trapping, it is recommended to perform a comprehensive analysis to determine the optimum injection rate and safe storage medium before operation.