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

J. B. Nicolaisen,L. Stemmerik,J. Rinna,J. E. Skeie,G. Elvebakk,S. Olaussen,J. Ahokas,J. A. Bojesen‐Koefoed

doi:10.1111/jpg.12724

J. B. Nicolaisen, L. Stemmerik + Show 6 more

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https://doi.org/10.1111/jpg.12724

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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, δ13C of the aromatic fraction and/or the Pr/Ph ratio. Relatively heavy δ13C values, a low gammacerane index and high Pr/Ph ratios characterize Lower Carboniferous non‐marine sediments, whereas evaporite‐associated facies have lighter δ13C, a higher gammacerane index and lower Pr/Ph ratios.

Highlights

The Norwegian part of the Barents Shelf covers an area of more than 300,000 km2 and is still considered a frontier petroleum province, with only 145 exploration wells drilled and two fields in production
The Upper Palaeozoic succession in the western Barents Sea consists of four second-order depositional sequences, each corresponding to a group in the lithostratigraphic scheme for the Norwegian Barents Sea (Figs 1, 2; Larssen et al, 2005)
The total organic matter (TOC) values range between 1 and 75 wt.%, and the organic-rich section has a cumulative thickness of more than 100 m. It can be distinguished from other Upper Palaeozoic source rocks in Svalbard by its high Pr/Ph ratios, heavy δ13C signatures and low gammacerane ratio

Summary

Introduction

The Norwegian part of the Barents Shelf covers an area of more than 300,000 km and is still considered a frontier petroleum province, with only 145 exploration wells drilled and two fields in production. The Norwegian authorities estimated that more than 60% of the undiscovered petroleum resources aNatural History Museum of Denmark, University of Copenhagen, Denmark. * corresponding author, email: The Upper Palaeozoic succession in the western Barents Sea consists of four second-order depositional sequences, each corresponding to a group in the lithostratigraphic scheme for the Norwegian Barents Sea (Figs 1, 2; Larssen et al, 2005). Upper Palaeozoic organic-rich units on Svalbard BFZ W2 W1 W3 G1 Greenland B1 E2 E3

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