The Norwegian Petroleum Directorate (NPD) has completed the mapping of possible CO 2 storage sites on the Norwegian shelf, and will publish an atlas of the southern part of the Barents Sea today.
The atlas was prepared on request from the Ministry of Petroleum and Energy, and completes the evaluation of the Norwegian Continental Shelf. The first CO2 storage atlas for the Norwegian part of the North Sea was launched two years ago, followed by an atlas of the Norwegian Sea earlier this year.
The mapping comprises the part of the Barents Sea that has been opened for petroleum activities, and shows that it is theoretically possible to store 7.2 billion tonnes (Gt) of CO2 in the reservoir rocks in the central part of this area. The sites in which it is possible to store CO2 are located in areas where petroleum activity is presumed to continue for many years to come. Potential future storage of CO2 on a large scale in the Barents Sea must therefore be viewed in the context of the interests of the petroleum industry.
It is possible to store approx. 70 million tonnes (Mt) of CO2 in structures with proven non-viable hydrocarbons. This is in addition to an estimated storage capacity of 200 Mt in the smaller structures in the Snøhvit development area. This may be relevant in the future, once gas production has been concluded and the structures abandoned.
In comparison, the Norwegian part of the North Sea is estimated to have a storage capacity of about 70 Gt, and the Norwegian Sea 5,5 Gt.
The atlases are based on information from seismic surveys and well and production data from the petroleum activities, but the Barents Sea is much more of a frontier area, compared with the North Sea and Norwegian Sea.
“A large part of the possible CO2 storage sites we have evaluated are considerably less mature than in the two other regions we’ve mapped,” says project manager Eva Halland.
In the work on the three atlases, the NPD has mapped aquifers (water bearing formations) and structures in the subsurface, and has then evaluated whether they are suitable for long-term, safe storage. One of the criteria is that the potential storage sites cannot have a negative impact on the current or future oil and gas activities.
“The Barents Sea is a frontier petroleum province, and oil and gas activities are ongoing in the entire area. It has therefore not been possible to delimit potential CO2 disposal areas against petroleum activities, as we have been able to do for the other regions,” says Halland.
Natural gas produced from the Barents Sea also contains CO2. This has been proven by several exploration wells drilled in the area. When the oil and gas fields are developed, there could be a need to remove this CO2.
During the work on the atlas, small and large structures that can be used to store CO2 from future field developments have therefore been evaluated.
Halland references the experiences from the Snøhvit field, where CO2 has been removed from the gas and deposited in the subsurface since 2007.
“This has provided us with a good understanding of how CO2 can be stored in the area,” she says.
An updated version containing all atlases is scheduled for publication next year.