The Significance of δ13C of Carbonate Cements in Reservoir Sandstones: A Regional Perspective from the Jurassic of the Northern North Sea

  1. Sadoon Morad
  1. C. I. Macaulay1,
  2. A. E. Fallick1,
  3. O. M. McLaughlin2,†,
  4. R. S. Haszeldine2 and
  5. M. J. Pearson3

Published Online: 17 APR 2009

DOI: 10.1002/9781444304893.ch17

Carbonate Cementation in Sandstones: Distribution Patterns and Geochemical Evolution

Carbonate Cementation in Sandstones: Distribution Patterns and Geochemical Evolution

How to Cite

Macaulay, C. I., Fallick, A. E., McLaughlin, O. M., Haszeldine, R. S. and Pearson, M. J. (1998) The Significance of δ13C of Carbonate Cements in Reservoir Sandstones: A Regional Perspective from the Jurassic of the Northern North Sea, in Carbonate Cementation in Sandstones: Distribution Patterns and Geochemical Evolution (ed S. Morad), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304893.ch17

Author Information

  1. 1

    Isotope Geosciences Unit, Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow G75 0QF, Scotland, UK

  2. 2

    Department of Geology and Applied Geology, University of Glasgow, Glasgow G12 8QQ, Scotland, UK

  3. 3

    Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen AB9 2UE, Scotland, UK

  1. Exxon Production Research Company, PO Box 2189, Houston, TX 77252-2189, USA

Publication History

  1. Published Online: 17 APR 2009
  2. Published Print: 29 MAY 1998

ISBN Information

Print ISBN: 9780632047772

Online ISBN: 9781444304893

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Keywords:

  • carbonate cements in reservoir sandstones, Jurassic of northern North Sea;
  • carbon isotopic compositions;
  • oxygen isotopic compositions;
  • Kimmeridge Clay Formation;
  • carbonate cements in submarine fan sandstones;
  • Tertiary sandstones of Texas Gulf Coast oil province

Summary

Diagenetic carbonate minerals in Jurassic reservoir sandstones from 13 oilfields of the northern North Sea record predominantly negative carbon isotopic (δ13C PDB) compositions. δ13C values range from +15.8‰ to −28.8‰ (358 analyses), but show a strong mode at −9 to −11‰. This observation indicates a very significant contribution of isotopically negative carbon derived from organic material, most likely the regional source rocks of the Kimmeridge Clay Formation. The strong mode in the δ13C data is significant because these diagenetic carbonate minerals could have grown in the reservoir sandstones from mixtures of carbon from many sources as different fluids passed through the sandstones during burial, and as hydrocarbons were generated during thermal maturation of the adjacent organic-rich mudrocks.

Upper Jurassic marine sands enclosed within organic-rich mudstones contain diagenetic carbonates with a much smaller range of δ13C than that observed for Middle Jurassic deltaic sands, although both data sets have strong modes around −10‰. We suggest that this −10‰ mode in carbon isotopic compositions may represent carbon derived from the decomposition of organic acids, rather than from the mixing of two or more isotopically different sources. The wider range in δ13C seen in carbonates from the Middle Jurassic deltaic sands reflects the wider range in fluid and CO2 sources available in such settings.