3.2.2.1. Deep Saline Formation Suitability

The process of map building is detailed in Appendix A. Once the prospectivity map was updated with recent regional studies, information was challenged with the exploration status of the various basins [25]. The map of exploration status edited in 2000 does not correspond to the current exploration status. Consequently the map was updated (Figure 13) with Geogreen internal knowledge.

This updated exploration status was used to specify the suitability of the basins at world scale where there was a lack of information. Indeed, when an area has not been heavily explored, the knowledge over its geology is supposed to be poorer than in heavily explored areas. This information about exploration status was used only in countries and areas where no public information is available about CO2 capacity. For instance, the map of exploration status was used for Russia and not for Australia, Europe nor USA.

Figure 13: Exploratory Status of World Basins (modified from Halbouty, 2000)

Furthermore, the world natural seismicity map was used to discriminate seismic active zones that storage projects must avoid as much as possible, for storage safety achievement.

The map of storage suitability proposes a ranking in four levels for sedimentary basins: highly suitable, suitable, possible, and unsuitable. The ranking “unproven” is used for basaltic formations, and extrusive volcanic rocks.

The rankings “Highly suitable” and “suitable” stand for areas where geological knowledge is good and where, at regional level, major geological characteristics seem appropriate for CO2 storage.

Similarly, areas labelled as “possible” are areas where the geological knowledge is limited and where the basin might have the necessary characteristics to host storage projects. It means that exploration is needed to increase knowledge over the area in order to confirm its potential for CO2 storage.

The higher the ranking of suitability, the higher the success ratio of a given storage project is to reach bankability. However, a project can fail to reach bankability in a highly suitable area, and succeed in reaching it in a possible area.

The following map (Figure 14) gives the world geological storage suitability as proposed by Geogreen in March 2011:

Figure 14: World Geological Storage Suitability