CHARACTERIZATION OF UPPER PALAEOZOIC ORGANIC‐RICH UNITS IN SVALBARD: IMPLICATIONS FOR THE PETROLEUM SYSTEMS OF THE NORWEGIAN BARENTS SHELF

• Published in: Journal of Petroleum Geology
• Main Authors: Nicolaisen, J. B., Elvebakk, G., Ahokas, J., Bojesen‐Koefoed, J. A., Olaussen, S., Rinna, J., Skeie, J. E., Stemmerik, L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2018
• Subjects: Svalbard
• Online Access: http://dx.doi.org/10.1111/jpg.12724; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjpg.12724; https://onlinelibrary.wiley.com/doi/pdf/10.1111/jpg.12724; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jpg.12724

Recent discoveries of hydrocarbons along the western margin of the Norwegian Barents Shelf have emphasised the need for a better understanding of the source rock potential of the Upper Palaeozoic succession. In this study, a comprehensive set of organic geochemical data have been collected from the Carboniferous – Permian interval outcropping on Svalbard in order to re‐assess the offshore potential. Four stratigraphic levels with organic‐rich facies have been identified: (i) Lower Carboniferous (Mississippian) fluvio‐lacustrine intervals with TOC between 1 and 75 wt.% and a cumulative organic‐rich section more than 100 m thick; (ii) Upper Carboniferous (Pennsylvanian) evaporite‐associated marine shales and organic‐rich carbonates with TOC up to 20 wt.%; (iii) a widespread lowermost Permian organic‐rich carbonate unit, 2–10 m thick, with 1–10 wt. % TOC; and (iv) Lower Permian organic‐rich marine shales with an average TOC content of 10 wt.%. Petroleum can potentially be tied to organic‐rich facies at formation level based on the gammacerane index, δ 13 C of the aromatic fraction and/or the Pr/Ph ratio. Relatively heavy δ 13 C values, a low gammacerane index and high Pr/Ph ratios characterize Lower Carboniferous non‐marine sediments, whereas evaporite‐associated facies have lighter δ 13 C, a higher gammacerane index and lower Pr/Ph ratios.