Oil migration makes the difference; regional distribution of carbonate cement δ13C in northern North Sea Tertiary sandstones

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doi: 10.1180/000985500546738
Authors:Macaulay, C. I.; Fallick, A. E.; Haszeldine, R. S.; McAulay, G. E.
Author Affiliations:Primary:
Scottish Universities Research and Reactor Centre, Isotope Geosciences Unit, East Kilbride, United Kingdom
University of Edinburgh, United Kingdom
University of Glasgow, United Kingdom
Volume Title:Mineral diagenesis and reservoir quality, the way forward
Volume Authors:Bain, D. C., editor; Hall, P. L.; Shaw, H. F.; Spears, D. A.
Source:Clay Minerals, 35(1), p.69-76; Sixth Cambridge conference on Mineral diagenesis and reservoir quality, the way forward, Cambridge, United Kingdom, March 26-27, 1998, edited by D. C. Bain, P. L. Hall, H. F. Shaw and D. A. Spears. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0009-8558
Publication Date:2000
Note:In English. 18 refs.; illus., incl. sketch map
Summary:Carbonate cements in Tertiary reservoir sandstones from the northern North Sea have distinctive carbon isotopic compositions (δ13C). Oil migration up faults from deeper structures and biodegradation of oil pools are factors of particular importance in influencing the δ13C of carbonate cements in these sandstones. As a result, δ13C can be used as an exploration guide to locating the positions of vertical leakoff points from the Jurassic source rocks. The histogram distribution of δ13C in these carbonate cements is trimodal, with peaks at around -26, -3 and +12 per mil (ranges -22 to -30, +2 to -10 and +8 to +18 per mil, respectively). Bacterial processes played major roles in determining this distribution, with oxidative biodegradation of oil resulting in carbonate cements with very negative compositions and bacterial fermentation resulting in the positive δ13C cements. δ13C distribution patterns may be used to differentiate Tertiary reservoir sandstones from Jurassic in the northern North Sea, and these regional carbonate cement δ13C datasets allow geologically useful inferences to be drawn from δ13C data from new sample locations.
Sections:Clay minerals
Subsections:Petrology; weathering; soils
Subjects:Biodegradation; C-13/C-12; Carbon; Carbonates; Cement; Cenozoic; Clastic rocks; Distribution; Geochemical indicators; Geochemistry; Isotope ratios; Isotopes; Migration; Petroleum; Petroleum exploration; Reservoir rocks; Sandstone; Sedimentary rocks; Stable isotopes; Tertiary; Atlantic Ocean; North Atlantic; North Sea; Northern North Sea
Coordinates:N573000 N590000 E0010000 E0000000
Abstract Numbers:01M/115
Record ID:2000057284
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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