LOwer CRETAceous project, summary of results

This thematic volume presents results from the LOCRETA project (2017–2021) which addressed some aspects of the Lower Cretaceous Cromer Knoll Group of the North Sea Basin The group includes two chalk formations, which host hydrocarbons in the North Sea and are subject to petroleum production: The Tuxen Formation of Hauterivian (BC 8, diachronic) to Barremian age (partly BC15) and the Sola Formation of Barremian (partly BC15) to Albian (BC23 to BC24, diachronic) age. In the area around the Valdemar field (central parts of the Danish Central Graben, DCG), each formation is up to 100 meter thick and buried to more than 2 km. The chalk is clay bearing and relatively soft, and the mechanical stability is a concern during hydrocarbon production. The interpretation of geophysical surface- and borehole data has also proven challenging, partly due to complex mineralogy and sparse information on pore water composition.
The LOCRETA project was initiated to address these rock mechanical and geophysical issues based on a revised spatial framework involving sedimentology, stratigraphy paleontology and geochemistry. To increase our understanding of the Lower Cretaceous, a study of the nearby and equivalent Vedsted Formations (Valanginian to Aptian/Albian) and Rødby Formation (Aptian/Albian) in the Danish Basin was also included.