This section aims at defining some of the key terms and concepts used in the study.
- Abandoned: relatively to Storage projects, stands for a project declared as being dropped
- Bankability: following the wording of the Invitation to Tender IEA/CON/10/180, a bankable site is a storage site that has been evaluated such that sufficient confidence exists in technical and cost elements, to support for commercial-scale projects.
- Commercial Scale project: stands for a project that is beyond bankability, and for which final investment for injection above 1 million tonnes of CO2 per year has been made, and that is ready to inject
- Currency: All costs are expressed in Euros. M€ stands for Million Euros (106 Euros) and bn€ stands for billion Euros (109 Euros). A conversion rate of 1.3 US dollar/Euro was used.
- Deep saline formation: water bearing formation whose salinity is exceeding sea water salinity
- Deep water: stands for sea water thickness of more than 300m
- Depleted hydrocarbon field: an hydrocarbon (either oil or gas) field that has reached the end of its lifetime
- EOR – EGR: enhanced hydrocarbon (either oil or gas) recovery
- Exploration: stands for phase of Storage project development which includes proper site characterization and validation through well drilling, 2D and/or 3D seismic, injection test, and corresponding engineering studies
- Failure cost: stands for the cost distribution of the storage part of a Storage project that has failed reaching bankability for technical (not financial nor administrative) reasons
- Failure ratio: stands for the probability of the storage part of a Storage project to fail reaching bankability for technical (not financial nor administrative) reasons
- Geological Province: stands for a spatial entity with common geologic attributes. A province may include a single dominant structural element such as a sedimentary basin, or a number of contiguous related elements. Adjoining provinces may be similar in structure but be considered separate due to differing histories.
- GIS: stands for Geographical information System
- IEA 2020/2050 Recommendation: Stands for the analysis and recommendation of International Energy Agency over the number of CCS project to be deployed by 2020 and 2050 respectively to achieve climate change mitigation objectives (450ppm blue map)
- Injection test: stands for a CO2 injection in a very limited quantity (up to 50,000 tonnes). Such injection test leads to bankability of a Storage project
- Jack-up rig: stands for a mobile bottom-supported offshore drilling structure with columnar or open-truss legs which can only be used in relatively shallow water depth (up to about 120m)
- Licensing: stands for the filing of an application to given national authorities for granting of an exploration license, or an injection test authorization
- MAGT: Migration Assisted Gravity Trapping, which stands for the counter effects of upward migration of gaseous carbon dioxide inside a dipping sedimentary formation, while the heavier density of carbon saturated brine balances this effect by downward migration of the same.
- Mobilization / Demobilization: stands for all operations related to bringing to site the required equipments (seismic equipments, drilling rig, logging tools…)
- OGIP: stands for originally gas in place. For a given gas field, it gives the amount of hydrocarbon contained inside a given trap.
- OOIP: stands for original oil in place. For a given oil field, it gives the amount of hydrocarbon contained inside a given trap.
- Probabilistic distribution: stands for a function of a discrete random variable (cost or time) yielding the probability that the variable will have a given value.
- Sedimentary Basin: stands for an area in which sediments have accumulated during a particular time period at a significantly greater rate and to a significantly greater thickness than surrounding areas.
- Semi-submersible (semi-sub) rig: stands for a floating offshore drilling unit that has pontoons and columns that when flooded cause the unit to submerge in the water to a predetermined depth
- Shallow water: stands for sea water column of less than 300m
- Stand-by: relatively to storage projects, stands for a project declared as being on hold
- Success cost: stands for the cost distribution of the storage part of a storage project that has reached bankability
Suitability: qualitative ranking (highly suitable, suitable, possible, unproven, unsuitable) of geological formations that is based upon the prospectivity for CO2 sequestration as defined by IPCC , crosschecked with geological world map, and history of exploration (mining or oil and gas). The higher the ranking of suitability, the higher the success ratio of a given storage project is, to reach bankability
- Highly suitable stand for areas where geological knowledge is very good and where, at regional level, major geological characteristics seem well appropriate for CO2 storage
- Suitable stand for areas where geological knowledge is good and where, at regional level, major geological characteristics seem appropriate for CO2 storage
- Possible stand for areas where geological knowledge is poor and where, at regional level, major geological characteristics could be appropriate for CO2 storage provided new data or information confirm it.
- Unproven stand for areas where geological storage of CO2 storage could occur according to present laboratory tests, but where no field test has yet confirmed it (case of ultrabasic and volcanic rocks).
- Storage complex: stands for the sedimentary column which includes the in which CO2 is injected, its caprock, and related upper geological formations, among others upper used for control.
Storage resource: characterized storage resource as defined in by IEA Figure 5). Coping with timelines for storage site injection start-up, requires that such resource identification process is compared with capacity estimates. Recent work by IEA GHG  has established a classification system in order to provide a set of definition for the CCS industry. This classification is shown on the following Figure 5.
- Storage capacity: practical storage capacity as defined in by IEA GHG  (Figure 5). Storage capacity are expressed in Million tonnes (1Mt = 106 metric tons) or Giga tonnes (1Gt = 109 metric tons)
- 2D and 3D seismic surveys: stands for surface seismic operations either onshore or offshore. They are divided in acquisition, processing, and interpretation.
- Well drilling: stands for all operations from rig-up to rig-down, including all appropriate data and samples collection.
- Workover: stands for any kind of operation on an existing well aimed at verifying its compliance for CO2 injection.