Seismic Characterization of Lower Cretaceous Clinoform Packages in the Fingerdupet Sub-basin, Southwestern Barents Sea
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The three wells drilled in Fingerdjupet Sub-basin during the late 1980’s were abandoned as dry holes, resulting in little exploration interest in the sub-basin. This leaves the depositional history poorly understood, and this study aims to give a better understanding of the infill history by studying different depositional styles on new seismic data. In 2013 and 2014, these new seismic surveys with high resolution were acquired, making it possible to investigate clinoforms in detail. This data allows investigation of low relief clinoforms geometry and size, and possibility to predict lithology based on outcrop analogues, which has not been possible with the previous datasets. Estimated porosity values are included for the different types of clinoforms and lithologies, resulting in a prediction of reservoir potential. This study is a part of a larger project, LoCrA (locra.ux.uis.no), which investigates the Lower Cretaceous basins in the Arctic. Seven sequences in the southwestern Barents Sea were already defined in this project, however only four of them are present in Fingerdjupet Sub-basin. The four seismic sequences within the Lower Cretaceous unit are described and interpreted in the north-south trending Early Cretaceous extensional basin: (1) Latest Hauterivian - Early Barremian age, consisting of mass transport complex, (2) Late Barremian - Early Aptian age, consisting of clinoforms, (3) Aptian age, consisting of local slumps, and (4) ?Albian age, consisting of clinoforms. In addition, three sub-sequences are interpreted within the second sequence (2), which are characterized by: (a) clinoform sets with a height of > 150 m and dip angles of around 3-6 degrees, interpreted as shelfal clinoforms, (b) clinoform sets with a height of < 40 m and dip angles of around 12 degrees, interpreted as shallow marine deposits due to observations of shingled progradational pattern, and (c) clinoforms with a height of < 80 m and dip angles of around 10 degrees, interpreted as deltaic clinoforms. The classification of the clinoforms indicates that the shallow water clinoforms observed in Sequence 2b, and c, have the geometry of sand-prone depositional systems, with an estimated average porosity of ~ 18 % for the compacted sediments.
Master's thesis in Petroleum geosciences engineering