Stratigraphic framework for Zechstein carbonates on the Utsira High, Norwegian North Sea

Lars Stemmerik, Kasper H. Blinkenberg, Ingrid P. Gianotten, Malcolm S.W. Hodgskiss, Aivo Lepland, Päärn Paiste, Israel Polonio, Nicholas M.W. Roberts, Niels Rameil

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The preserved Zechstein succession on the Utsira High in the NE part of the Norwegian North Sea is 25-100 m thick and is dominated by shelf carbonates. Internal subdivision of the succession is based on the recognition of key surfaces in petrophysical logs and cores, and suggests that the carbonates mainly consist of ZS2 and ZS3 deposits and that younger ZS4 and ZS5 deposits are only locally preserved. The carbonates have undergone early, syn-depositional dolomitization followed by later dolomite recrystallization and calcitization. Calcitization, interpreted as dedolomitization, is restricted to the upper part of the ZS3 carbonate unit and based on U/Pb dating took place during the Triassic, with a later phase of recrystallization linked to mid-Jurassic uplift. Both dedolomitization and dolomite recrystallization relate to fresh-water infiltration with the resetting of δO18 values prior to the Late Jurassic drowning of the Utsira High. The reservoir quality of the carbonates is directly linked to post-depositional meteoric diagenesis, and the best reservoir properties are recorded in intervals dominated by recrystallized dolomites in ZS2 and lower ZS3 carbonates. Dedolomitization significantly reduced porosity in the upper ZS3 carbonates.

Original languageEnglish
Pages (from-to)257-274
Number of pages18
JournalJournal of Petroleum Geology
Volume46
Issue number3
DOIs
Publication statusPublished - Jul 2023

Keywords

  • carbonate-evaporite systems
  • dedolomitization
  • Norwegian North Sea.
  • reservoir potential
  • U/Pb geochronology
  • Upper Permian
  • Utsira High
  • Zechstein Supergroup

Programme Area

  • Programme Area 3: Energy Resources

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