Indicators of hot fluid migration in sedimentary basins: evidence from the UK Atlantic Margin

Wycherley, H.L., Parnell, J., Watt, G.R., Chen, H. and Boyce, A.J. (2003) Indicators of hot fluid migration in sedimentary basins: evidence from the UK Atlantic Margin. Petroleum Geoscience, 9(4), pp. 357-374.

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Abstract

Microthermometric, petrographic and isotopic methods have been used to detect evidence for hot fluid flow in Mesozoic and Tertiary sediments from the NW UK continental margin, West of Shetland. New data presented here show that temperatures are hotter by c. 40°C in Tertiary samples than in the underlying Jurassic and Cretaceous sediments in wells 204/28-1, 206/5-2, 208/27-1, especially in cements from samples as young as mid–upper Eocene in age. Paleocene samples can be discriminated from older (Jurassic and Cretaceous) and younger (Eocene) sandstones on the basis of silica cement morphology and cathodoluminescence zonation. Jurassic, Cretaceous and Eocene quartz cements show oscillatory zoning as a consequence of relatively slow burial cementation. In direct contrast, rapid precipitation of silica cements from the cooling of hot fluids has produced unzoned cements in all but one Paleocene sample. No evidence for unzoned quartz cements was noted in any pre-Paleocene or Eocene samples. The restriction of hot fluid inclusions and unzoned cements to the Paleocene and post-Paleocene is consistent with lateral focusing of hot fluids. Isotopic data from kaolinites indicate that these fluids are best represented by mixtures of Mesozoic or Tertiary meteoric waters and marine porewaters that have undergone isotopic alteration through interaction with volcanic material. Our results indicate that hot fluid flow occurred over a relatively long time-scale (i.e. several million years), which may have important consequences for the degradation of reservoired hydrocarbons in West of Shetland Paleocene plays.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Boyce, Professor Adrian
Authors: Wycherley, H.L., Parnell, J., Watt, G.R., Chen, H., and Boyce, A.J.
Subjects:Q Science > QE Geology
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Petroleum Geoscience
Publisher:Geological Society of London
ISSN:1354-0793
Copyright Holders:© 2003 The Geological Society of London
First Published:First published in Petroleum Geoscience 9 (4):357-374
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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