CHARACTERIZATION OF UPPER PALAEOZOIC ORGANIC‐RICH UNITS IN SVALBARD: IMPLICATIONS FOR THE PETROLEUM SYSTEMS OF THE NORWEGIAN BARENTS SHELF. (10th December 2018)

• Record Type: Journal Article
• Authors: Nicolaisen, J. B.; Elvebakk, G.; Ahokas, J.; Bojesen‐Koefoed, J. A.; Olaussen, S.; Rinna, J.; Skeie, J. E.; Stemmerik, L.
• Is Part Of: Journal of petroleum geology. Volume 42:Number 1(2019)
• Page Start: 59
• Page End: 78
• Publication Date: 2018-12-10
• Subjects: Norway -- Barents Sea -- Svalbard -- Spitsbergen -- Upper Palaeozoic -- source rocks -- petroleum -- geochemistry -- gammacerane index -- biomarkers -- isotope ratios; Petroleum -- Geology -- Periodicals; Aardolie; Electronic journals; 553.28
• DOI: 10.1111/jpg.12724
• Languages: English
• ISSNs: 0141-6421

Abstract

Abstract : 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.