RAUDE FM
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General information
General information Attribute Value Lithostrat. unit The lithostratigraphic unit's official name.RAUDE FMNPDID lithostrat. unit Norwegian Offshore Directorate's unique id for lithostratigraphic units.127Level Indicates the lithostratigraphic unit's level. Legal values: GROUP, FORMATION, MEMBER.FORMATIONLithostrat. unit, parent The parent lithostratigraphic unit's official name. See also level. Will be empty if Level = GROUP. -
Level below
Level below Lithostrat. unit -
Description
Raude Formation
NameThe formation is named after Eirik Raude (Raude=Red), the Viking discoverer of Greenland.Well type sectionWell reference sectionThicknessIn the type well the formation is 161 m thick and in 211/24-1 it is 119 m.LithologyIn the type well the basal part of the formation consists of a coarsening upward sequence of grey, green, and red-brown silty claystones, grey arkosic sandstones and white, pink and grey-brown dolomitic limestones. This basal part of the section is often difficult to recognise away from the type well and is locally absent. Above 2905 m in the type well the formation consists of approximately equal amounts of sandstone and silty shale. These sandstones are fine to medium grained and poor to moderately sorted with subangular grains. They are generally micaceous and have a kaolinitic matrix. The silty shales are grey and light green or occasionally red-brown in colour, and micromicaceous. Carbonaceous debris, sometimes in thin laminae, is present but distinct lignite beds are absent. Away from the type well the sandstone percentage in the upper part of the formation may vary from about 15 to about 75. In the area of the Brent and Statfjord fields the average sandstone bed thickness is about 2.5 m and shale beds average about 4 m in thickness. Correlation of individual beds from well to well is virtually impossible.
In well 33/12-5 the Raude Formation consists of alternating, 5 to 10 m-thick, red claystones and sandstones, except for the lowermost 25 m of claystone, while in well 30/6-5 a similar pattern as in the type well is observed.BoundariesThe originally Raude Member of the Statfjord Formation was elevated to formation level by Lervik, 2006. The base of the formation is the base of the Statfjord Group . The change from the underlying more argillaceous sediments to the more sandy Statfjord Group via the transitional coarsening-upward units is clearly defined on the gamma ray and sonic logs. The top of the formation is the base of the first massive sandstone of the overlying more arenaceous formation. This boundary is normally clearly marked by a change from irregular to a blockier log response, particularly in the gamma ray log. Individual sandstone beds in the overlying Eiriksson Formation are more laterally extensive. The base of the lowermost sandstone can be well correlated which will generally indicate the top of the Raude Formation.DistributionThe formation can generally be recognized wherever the Statfjord Group is well developed. The basal coarsening upward unit is thought to have a more limited distribution but this cannot be defined as many wells terminated in or just above this basal unit.AgeRhaetian. The top of the formation may approximate to the Rhaetian – Lower Jurassic boundary in the type well but is probably older to the west (Fig 1.18) .Depositional environmentThe Raude Formation was interpreted as a braided-stream, based on the lithological content and sedimentary structures in the upper part of the formation, particularly large cross-bedding, scour and fill, Deegan and Scull (1977), Røe and Steel (1985) interpreted the few component sandstones within Raude Formation as distal alluvial-fan stream deposits in a flood-basin environment. Mudstones of reddish-brown or mottled colours with palaeosols may represent a subaerial, well-drained floodplain environment (Nystuen and Fält, 1995). Carbonate nodules, root structures and dessication cracks are abundant in the palaeosols.Compiled from-
Deegan, C. E. and Scull, B. J. (compilers) 1977: A standard lithostratigraphic nomenclature for the Central and Northern North Sea. UK Institute of Geological Sciences, Report 77/25. The Norwegian Petroleum Directorate, NPD-Bulletin No. 1, 36 pp.
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Goldsmith, P. J., Hudson, G. and Van Veen, P. Triassic. 105 – 127 in: Evans, D., Graham, C., Armour, A. and Bathurst, P. (editors and coordinators) 2003: The Millennium Atlas: petroleum geology of the central and northern North Sea. The Geological Society of London, 389 pp.
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Lervik, K.-S. 2006: Triassic lithostratigraphy of the Northern North Sea Basin. Norwegian Journal of Geology, Vol. 86, pp. 93-116.
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Wellbores penetrating
Wellbores penetrating 31.07.20212316238309.01.20203067312016.02.19813394356722.09.19792959300316.12.19823334338912.05.19903332338708.02.19842855290020.05.19844161424926.12.20144411445924.07.20124332437723.08.19742790295108.05.19813957407419.05.20154723475406.03.20222918304530.05.19852586265416.12.19852629267829.10.19862620268308.09.19782329236708.12.19783497354007.06.19792677271510.10.19872674271215.10.19792458248102.01.19802732276423.03.19802140218014.07.19832137217705.03.19812000208922.10.19843930400513.07.19873488353810.08.19873488353811.04.20014165437008.07.20013982420018.04.20144635465626.03.201772747390 -
Wellbores with cores