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

Published online by Cambridge University Press:  09 July 2018

R. W. O'B. Knox
Affiliation:
British Geological Survey, Keyworth, Nottingham NG12 5GG
W. G. Burgess
Affiliation:
Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OXI0 8BB
K. S. Wilson
Affiliation:
Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OXI0 8BB
A. H. Bath
Affiliation:
British Geological Survey, Keyworth, Nottingham NG12 5GG

Abstract

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.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1984

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References

Bird, M.J. (1981) Hydraulic properties of core samples from the Marchwood geothermal borehole. Institute of Geological Sciences Hydrogeology Unit Report WD/ST/81/6.Google Scholar
Burgess, W.G., Burley, A.J., Downing, R.A., Edmunds, W.A. & Price, M. (1981) The Marchwood geothermal borehole—a preliminary assessment of the resource. Unpubl. Inst. Geol. Sci. Report. Google Scholar
Burley, S.D. (1984) Patterns of diagenesis in the Sherwood Sandstone Group (Triassic), United Kingdon. Clay Miner. 19, 403440.Google Scholar
Colter, V.S. & Havard, D.J. (1981) The Wytch Farm Oil Field, Dorset. Pp. 494503 in: Petroleum Geology of the Continantal Shelf of North-West Europe (Ming, L. V. & Hobson, G. D., editors). Institute of Petroleum, London.Google Scholar
Edmunds, W.M. & Wright, E.P. (1979) Groundwater recharge and palaeoclimate in the Sirte and Kufra Basins, Libya. J. Hydrol. 40, 215241.Google Scholar
Fatt, I. (1956) The network model of porous media. Trans. Am. Inst. Min. Metall. Petrol. Engrs (Petroleum Transactions) 207, 144159.Google Scholar
Irwin, H., Curtis, C. & Coleman, M. (1977) Isotopic evidence for the source of diagenetic carbonates formed during burial of organic-rich sediments. Nature 269, 209213.Google Scholar
Lott, G.K. & Strong, G.E. (1982) The petrology and petrography of the Sherwood Sandstone (?Middle Triassic) of the Winterborne Kingston borehole, Dorset. Pp. 135142 in: The Winterborne Kingston borehole, Dorset, England (Rhys, G. H., Lott, G. K. & Calver, M. A., editors). Rep. Inst. Geol. Sci. 81/3.Google Scholar
Morton, A.C. (1982) Heavy minerals from the sandstones of the Winterborne Kingston borehole, Dorset. Pp. 143148 in: The Winterborne Kingston borehole, Dorset, England (Rhys, G. H., Lott, G. K. & Calver, M. A., editors). Rep. Inst. Geol. Sci. 81/3.Google Scholar
Price, M. & Allen, D.J. (1984) The use of pumping tests to evaluate a geothermal reservoir—the Triassic sandstones at Marchwood, Southampton. Proc. Civ. Eng. (in press).Google Scholar
Rhys, G.H., Lott, G.K. & Calver, M.A. (1982) The Winterborne Kingston borehole, Dorset, England. Rep. Inst. Geol. Sci. 81/3.Google Scholar
Richardson, S.W. & Oxburgh, E.R. (1979) The heat flow field in mainland U.K. Nature 282, 565567.CrossRefGoogle Scholar
Salomons, W., Goudie, A. & Mook, W.G. (1978) Isotopic compositions of calerete deposits from Europe, Africa and India. Earth Surface Processes 3, 4357.Google Scholar
Wardlaw, N.C. & Taylor, R.P. (1976) Mercury capillary pressure curves and the interpretation of pore structure and capillary behaviour in reservoir rocks. Bull. Can. Petrol. Geol. 24, 225262.Google Scholar