Abstract CO2 Capture and geological Storage (CCS) is a technology that is available today and that can cost-effectively solve up to a quarter of the global Greenhouse gas (GHG) problem. CCS can be applied to any fixed, point-source of CO2, and will likely be most cost-effective when applied to large sources close to large sinks. While CCS has application in the oil and gas sector (both upstream and downstream), the largest sources of CO2 exist in the power sector. Oil and gas sources are typically less than one million metric tonnes per annum (mmtpa) CO2, whereas power sector sources are typically more than 5mmtpa CO2. Hence a large-scale sequestration project should store in the order of lmmtpa CO2. Around 30mmtpa CO2 is being injected into EOR projects, mostly in the USA and Canada. Those EOR projects are being managed to recover and re-inject the CO2 (that they have to buy), rather than sequester it - little or no monitoring is carried out for the purpose of assuring CO2 geological storage As of today, there are only 4 large-scale projects on the planet which sequester anthropogenic CO2 on the lmmtpa-scale: Sleipner (Norway), In Salah (Algeria), Weyburn-Midale (Canada) and Snøhvit (Norway). Of these the two most significant (in terms of cumulative volume injected and experience of CO2 storage) are Sleipner (which has been in operation for 13 years) and In Salah (5 years). Weyburn-Midale is a CO2 EOR project involving CO2 cycling and monitoring. Although a portion of the cycled CO2 will be permanently stored, the primary objective of the project is to recover EOR oil. Snøhvit is relatively new (starting injection in 2008) and has not yet stored a significant volume of CO2. We focus therefore on the experience from the two large and mature projects Sleipner and In Salah. These two projects both capture CO2 produced during natural gas processing and store CO2 in deep saline formations. For both projects, the storage was part of the integrated Field Development Plan. They were both permitted under hydrocarbon law, and they illustrate significantly different aspects of storage: technical and commercial.