Peer Hoth, BGR (Germany)
Saulius Sliaupa, Institute of Geology and Geography (Lithuania)
Herrmann Wehner, BGR (Germany)
Joachim Piske, Petrobranch (Germany)
The petroleum system of the Baltic region is formed by Cambrian siliciclastic, Ordovician and Silurian carbonate reservoirs and organic rich shales of the same age. Burial and temperature conditions as well as lithofacies vary significantly across the basin.
Source rock and oil samples were collected from several offshore and onshore wells. Two types of oils from Cambrian reservoirs were identified based on their chemical composition. Differences between the oils from the Polish offshore area and the central parts of the basin are mainly caused by variances of the sedimentary environment during source rock deposition in the different basin parts. The investigation of the maturity of the organic matter in the shales indicates that some areas still have good source rock potential. In contrast, this potential is nearly or totally exhausted in large areas and especially in the deepest part of the basin. Maturity of the organic matter increases to the west pointing to increasing maximum burial depth in the past.
Subsidence modelling of wells from the Ruegen sector (NE-Germany) across the Baltic Sea to the eastern part of Lithuania was performed in order to reconstruct oil generation as well as subsidence history of the basin. Modelling results show, that the western part of the basin was placed in the oil window during the Late Silurian, whereas oil started to generate in the central part during the Middle-Late Devonian.