Middle Jurassic, Upper Jurassic and Lower Cretaceous of the UK Central and Northern North Sea Continental Shelf and Margins Programme Research Report RR/03/001 BRITISH GEOLOGICAL SURVEY RESEARCH REPORT RR/03/001 Middle Jurassic, Upper Jurassic and Lower Cretaceous of the UK Central and Northern North Sea The National Grid and other Ordnance Survey data are used with the permission of the Authors Controller of Her Majesty’s Stationery Office. Licence No: 100017897/2005. H Johnson, A B Leslie, C K Wilson, I J Andrews and R M Cooper Keywords Contributors Central and Northern North Sea, Middle Jurassic, Upper Jurassic, P Egerton, E Gillespie, A F Henderson, S Jones, M F Quinn and J B Wild Lower Cretaceous Front cover Glacial till overlying Oxfordian sedimentary rocks at Filey Brigg, North Yorkshire. Bibliographical reference JOHNSON, H, LESLIE, A B, WILSON, C K, ANDREWS, I J, and COOPER, R M. 2005. Middle Jurassic, Upper Jurassic and Lower Cretaceous of the UK Central and Northern North Sea. British Geological Survey Research Report, RR/03/001. 42pp. ISBN 0 85272 509 4 Copyright in materials derived from the British Geological Survey’s work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail [email protected]. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract. Maps and diagrams in this book use topography based on Ordnance Survey mapping. © NERC 2005. All rights reserved. Keyworth, Nottingham British Geological Survey 2005 BRITISH GEOLOGICAL SURVEY British Geological Survey offices The full range of Survey publications is available from the BGS Sales Desks at Nottingham, Edinburgh and London; see contact Keyworth, Nottingham NG12 5GG details below or shop online at www.geologyshop.com ຜ 0115–936 3100 Fax 0115–936 3200 e-mail: sales @bgs.ac.uk The London Information Office also maintains a reference www.bgs.ac.uk collection of BGS publications including maps for consultation. Online shop: www.geologyshop.com The Survey publishes an annual catalogue of its maps and other Murchison House, West Mains Road, Edinburgh EH9 3LA publications; this catalogue is available from any of the BGS ຜ 0131–667 1000 Fax 0131–668 2683 Sales Desks. e-mail: [email protected] The British Geological Survey carries out the geological survey London Information Office at the Natural History Museum of Great Britain and Northern Ireland (the latter is an agency (Earth Galleries), Exhibition Road, South Kensington, London service for the government of Northern Ireland), and of the SW7 2DE surrounding continental shelf, as well as its basic research ຜ 020–7589 4090 Fax 020–7584 8270 projects. It also undertakes programmes of British technical aid ຜ 020–7942 5344/45 e-mail: [email protected] in geology in developing countries as arranged by the Department for International Development and other agencies. Forde House, Park Five Business Centre, Harrier Way, Sowton, Exeter, Devon EX2 7HU The British Geological Survey is a component body of the ຜ 01392–445271 Fax 01392–445371 Natural Environment Research Council. Geological Survey of Northern Ireland, Colby House, Stranmillis Court, Belfast BT9 5BF ຜ 028–9038 8462 Fax 028–9038 8461 Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB ຜ 01491–838800 Fax 01491–692345 Columbus House, Greenmeadow Springs, Tongwynlais, Cardiff, CF15 7NE ຜ 029–2052 1962 Fax 029–2052 1963 Parent Body Natural Environment Research Council, Polaris House, North Star Avenue, Swindon, Wiltshire SN2 1EU ຜ 01793–411500 Fax 01793–411501 Foreword The North Sea Oil Province comprises the Central and Graben rift systems. During Early Cretaceous times, much Northern North Sea and is one of the world’s major oil- of the pre-existing rift topography continued to exert a producing regions. For the past 30 years this province has strong influence on sedimentation, though tectonism and been a very important part of Britain’s resource base and a halokinesis were also locally important. Syn-rift organic- major contributor to the Nation’s wealth. The private rich marine mudstones are the source for virtually all of the sector’s success in vigorously exploring and developing the region’s hydrocarbons and are mature for hydrocarbon oil province has been supported and stimulated by the generation throughout most of the rift system. Though the regulatory activities of the Department of Trade and Central and Northern North Sea is now considered to be Industry, and by the complementary work of the British mature for exploration, plays such as the Upper Jurassic Geological Survey (BGS), which has published an syn-rift play and the deep basin-axis high pressure/high extensive range of offshore geological maps and reports. temperature gas condensate play are expected to be the This report summarises much that is known about the focus of much future activity. For example, the recent giant tectono-stratigraphic development, palaeogeography and ‘Buzzard’ discovery in Upper Jurassic sandstones of the petroleum geology of the Middle Jurassic, Upper Jurassic Central North Sea may have oil in place ranging from 800 and Lower Cretaceous rocks within the province. The to 1100 million barrels, making it one of the largest report text and figures presented here are complemented by discoveries on the United Kingdom Continental Shelf in three 1:1 000 000 map enclosures that illustrate the the last 25 years. The Lower Cretaceous succession has distribution and thickness of the Middle Jurassic, Upper also been a recent exploration target, and significant Jurassic and Lower Cretaceous lithostratigraphical discoveries have been reported within the Moray Firth successions as defined by the BGS on behalf of the United Basin. Kingdom Offshore Operators Association. The Middle Jurassic development of the province was dominated by an episode of transient thermal doming. A David A Falvey subsequent, Late Jurassic, phase of crustal extension Executive Director developed the Viking Graben, Moray Firth and Central British Geological Survey iii Acknowledgements This report was compiled by H Johnson, A B Leslie, C K Wilson and I J Andrews, with editorial advice from D Evans and J Thomas. Figures were prepared by J Bain, M Cherrie and A Stewart. iv Contents Foreword iii along the axis of the Viking Graben (after Underhill Acknowledgements iv and Partington, 1993) 12 9 Middle Jurassic palaeogeography (after Mitchener et 1 Introduction 1 al., 1992) 13 1.1 Structural development 1 10 Simplified map of the Rattray Volcanics Member of 1.2 Stratigraphic templates 8 the Forties Volcanic Province; numbers refer to UK 2 Brent and Fladen Groups (‘Middle Jurassic’) 9 quadrants (after Smith and Ritchie, 1993) 14 2.1 Introduction 9 11 Depositional model for the Rannoch, Etive and Lower 2.2 Lithostratigraphy 9 Ness formations (after Budding and Inglin, 1981) 14 2.3 Sequence stratigraphy 10 12 Depositional setting of the Brent and Fladen groups 15 2.4 Palaeogeography 10 13 Summary of diagenetic and burial history of the Brent 2.5 Depositional environments and reservoirs 12 Group (after Giles et al., 1992) 16 2.6 Source rocks 14 14 Structure of the Murchison Oilfield (after Warrender, 2.7 Traps 14 1991) 16 15 Structure of the Brent Oilfield (after Struijk and Green, 3 Humber Group (‘Upper Jurassic’) 18 1991) 17 3.1 Introduction 18 16 Structure of the Bruce Oilfield (after Beckly et al., 3.2 Lithostratigraphy 18 1993) 17 3.3 Sequence stratigraphy 19 17 Humber Group (Upper Jurassic) lithostratigraphy (after 3.4 Palaeogeography 19 Richards et al., 1993; Andrews et al., 1990; Wignall 3.5 Depositional environments and reservoirs 22 and Pickering, 1993) 19 3.6 Source rocks 23 18 Genetic stratigraphy template for the Late Jurassic of 3.7 Traps 25 the UK Central and Northern North Sea (after 4 Cromer Knoll Group (‘Lower Cretaceous’) 27 Partington et al., 1993b and Fraser et al., 2003) 20 4.1 Introduction 27 19 Upper Jurassic palaeogeography (after Rattey and 4.2 Lithostratigraphy 27 Hayward, 1993) 21 4.3 Sequence stratigraphy 28 20 Depositional setting of the Humber Group 22 4.4 Palaeogeography 30 21 Depositional model for the Fulmar Formation (after 4.5 Depositional environments and reservoirs 32 Gowland, 1996) 23 4.6 Traps 35 22 Schematic block-diagram of the depositional setting of References 38 Upper Jurassic sediments in the Brae Oilfield area (after Stoker and Brown, 1986) 24 23 Approximate thermal maturity at top Kimmeridge Clay FIGURES Formation (after Cayley, 1987; Field, 1985; Goff, 1983) 25 1 Structural framework of the Central and Northern 24 Structure of the South Brae Field (after Roberts, 1991) 26 North Sea. Approximate locations of cross-sections in 25 Structure of the Clyde Field (after Smith, 1987) 26 Figure 5 as well as Figures 14, 15, 16, 24, 25, 32, 33, 26 Cromer Knoll Group (Lower Cretaceous) 34 and 35 are shown 2 lithostratigraphy (after Johnson and Lott, 1993) 28 2 Location of Central and Northern North Sea hydrocarbon 27 Generalised Early Cretaceous sequence stratigraphy fields in the Middle Jurassic, Upper Jurassic and Lower (after Oakman and Partington, 1998; Copestake et al., Cretaceous (after Brooks et al., 2002) 3 2003) 29 3 Generalised tectonic phases of the Central and 28 Chronostratigraphic distribution of Early Cretaceous Northern North Sea