Diagenetic influences on reservoir properties of the Sherwood Sandstone (Triassic) in the Marchwood geothermal borehole, Southampton, UK

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Authors:Knox, R. W. O'B.; Burgess, W. G.; Wilson, K. S.; Bath, A. H.
Author Affiliations:Primary:
Br. Geol. Surv., Keyworth, United Kingdom
Univ. London, Queen Mary Coll., Dep. Geol. Sci., United Kingdom
Volume Title:Patterns of mineral diagenesis on the NW European continental shelf and their relations to facies and hydrocarbon accumulation
Volume Authors:Morgan, D. J., editor; Rawson, P. F.
Source:Clay Minerals, 19(3), p.441-456; Joint meeting of the Clay Minerals Group of the Mineralogical Society and the Petroleum Exploration Society of Great Britain ; Patterns of mineral diagenesis on the NW European continental shelf and their relations to facies and hydrocarbon accumulation, Cambridge, United Kingdom, April 7-8, 1984, edited by D. J. Morgan and P. F. Rawson. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0009-8558
Publication Date:1984
Note:In English. 14 refs.; illus. incl. 2 tables, strat. col., sketch map
Summary:Petrological studies of the Sherwood Sandstone of the Marchwood Borehole show that the formation is made up of two units of differing primary lithological character: a lower unit with lithic sandstone and conglomerate, and an upper unit with arkosic sandstone. A combination of compaction and calcite cementation (early and late) has severely reduced porosity and permeability in the lower unit. In the upper unit compaction is again important, but several beds have largely escaped cementation, and their primary porosity has been enhanced by leaching of feldspars. The secondary porosity reaches 7% in some samples. Oxygen and carbon isotope data for the early (calcrete) cements indicate isotopic equilibrium with typical freshwater compositions. The later cements yield more variable values, indicating precipitation under a wider range of conditions. [D.J.M.]
Subjects:Boreholes; C-13/C-12; Calcite; Calcrete; Carbon; Carbonate rocks; Carbonates; Cement; Cementation; Clastic rocks; Compaction; Conglomerate; Controls; Cores; Diagenesis; Geothermal energy; Isotopes; Materials; Mesozoic; O-18/O-16; Oxygen; Porosity; Precipitation; Properties; Reservoir rocks; Sandstone; Secondary porosity; Sedimentary petrology; Sedimentary rocks; Sherwood Sandstone; Stable isotopes; Triassic; England; Europe; Great Britain; United Kingdom; Wessex Basin; Western Europe; Marchwood geothermal borehole; Ratios; Southampton
Abstract Numbers:85M/2026
Record ID:1985033741
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
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