Abstract Reservoir engineering is an important factor in the planning and execution of a CO 2 sequestration project. Site characterization concerns issues such as the integrity of the top seal, the depth of the storage formation, the storage capacity, and the use of history matching in depleted oil and gas reservoirs. Numerical modeling of the CO 2 injection and migration helps in the design of the injection plan, predicting the CO 2 migration path, determining the amount of CO 2 that can be safely injected, and performing risk assessment. In the long term, various trapping mechanisms are involved in securing the CO 2 in place. We briefly review related studies in these areas, present some results of the reservoir engineering modeling work of a pilot project, and use generic models to illustrate the concepts, approaches, and considerations in reservoir engineering aspects in CO 2 sequestration processes.