Screening of prospective sites for geological storage of CO₂ in the Southern Baltic Sea

The BASTOR project focuses on identifying and characterising potential sites for CO₂ storage in the southern Baltic Sea region. A compilation of available digital data from well logs, seismic line data interpretations, mapped structure outlines and published material from existing hydrocarbon fields and identified and mapped structures from Sweden, Poland, Latvia, Lithuania and Kaliningrad have been incorporated into a regional GIS for the Baltic Sea region. A detailed screening of regional sedimentary basins identified the Slupsk Border Zone as having suitable structures for storage of CO₂ in depleted oil and gas fields or saline aquifers. Cambrian sandstone saline aquifers below 900 m have been identified as the principal regional potential storage target with the Dalders Monocline as the most promising area. Eight individual structures were identified as having greatest potential. Detailed 3D geological static models were developed for three of these structures located in offshore Latvia (E6 and E7) and one cross-border structure (Dalders Structure). A theoretical regional CO₂ storage capacity calculation based on the GeoCa-pacity methodology was undertaken. A regional storage capacity for Cambrian sandstones below 900 m was estimated at a total of 16 Gt, with 2 Gt for the Dalders Monocline. Theoretical storage estimates for individual structures for the Baltic Sea regions includes 760 Mt for the Latvian structures and the Dalders Structure, 9.1 Mt for the structures located in Poland, 31 Mt in Lithuania and 170 Mt in Kaliningrad. These estimates are based on the best available data at the time of writing. However these estimates will be improved upon as new data becomes available from other sources.