Palaeohydrodynamic fluid flow regimes during diagenesis of the Brent Group in the Hutton-NW Hutton reservoirs; constraints from oxygen isotope studies of authigenic kaolin and reverse flexural modelling

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Authors:McAulay, G. E.; Burley, S. D.; Fallick, A. E.; Kusznir, N. J.
Author Affiliations:Primary:
University of Manchester, Department of Geology, Manchester, United Kingdom
Other:
Scottish Universities Research and Reactor Centre, United Kingdom
University of Liverpool, United Kingdom
Volume Title:Issue devoted to papers read at a conference on Diagenesis, overpressure and reservoir quality
Volume Authors:Bain, D. C., editor; Hall, P. L.; Shaw, H. F.; Spears, D. A.
Source:Clay Minerals, 29(4), p.609-626; Diagenesis, overpessure and reservoir quality, Cambridge, United Kingdom, March 26, 1993, 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:1994
Note:In English. 51 refs.; illus., incl. sects., 1 table, sketch maps
Summary:Authigenic kaolin is a major occluder of porosity at all depths in the Hutton-NW Hutton Brent Group reservoirs. Two polytypes, kaolinite and dickite, are present. Kaolinite occurs to a depth of ∼10,600 ft and is interpreted to be eogenetic. Dickite increases in abundance with burial depth, concomitant with increasing K-feldspar dissolution. Kaolin petrography indicates that kaolinite transforms to dickite via dissolution-reprecipitation at depths of ∼11,000 ft. Dickite has δ18O values characteristic of modified meteoric water for growth at temperatures of contemporaneous quartz authigenesis. Palaeohydrodynamic models involving meteoric water penetration down to 2 km through faults or Palaeozoic rocks of the East Shetland Platform are unlikely to provide the vigorous fluid throughput required for kaolin precipitation. Reverse post-rift modelling indicates that the crest of the Hutton-NW Hutton fault block was not sub-aerially exposed, precluding meteoric water ingress via this route. Eogenetic kaolinite formed in a meteoric water flush driven by topographic head on the Brent Delta. Dickite is, in part, derived from kaolinite dissolution, with additional sourcing from K-feldspar dissolution and Si-Al in pore-waters expelled from mudstones during burial. This model precludes the need for extensive fluid-flushing at intermediate burial depths.
Subjects:Bajocian; Brent Group; Burial diagenesis; Clastic sediments; D/H; Diagenesis; Flexure; Hydrodynamics; Hydrogen; Isotope ratios; Isotopes; Jurassic; Kaolin; Mesozoic; Meteoric water; Middle Jurassic; O-18/O-16; Oxygen; Petroleum; Pore water; Porosity; Reservoir rocks; Sediments; Stable isotopes; Atlantic Ocean; East Shetland Basin; North Atlantic; North Sea; Hutton Field; NW Hutton Field
Abstract Numbers:95M/3631
Record ID:1995025466
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
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