FRUHOLMEN FM
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General information
General information Attribute Value Lithostrat. unit The lithostratigraphic unit's official name.FRUHOLMEN FMNPDID lithostrat. unit Norwegian Offshore Directorate's unique id for lithostratigraphic units.46Level 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
Fruholmen Formation
NameFrom a lighthouse on a skerry north of Ingøy in Finnmark. The present formational concept embraces the two units T2-1 and T2-2 (Helgøy and Ytterøy formations) of earlier informal usage.Well type sectionWell 7121/5-1 (Statoil), coordinates 71°35'54.88"N, 21°24'21.78"E, from 2793 m to 2572m (Fig 4.46) .Well reference sectionWell 7120/12-1 (Norsk Hydro), coordinates 71°06'48.7"N, 20°45'20.1"E, from 2535 m to 2337 m (Fig 4.47) .ThicknessLithologyBasal grey to dark grey shales pass gradually upwards into interbedded sandstones, shales and coals. Sand dominates in the middle of the formation in several wells, while the upper part is more shaly, prompting a tripartite subdivision into (ascending order) the Akkar (Squid) Reke (Prawn) and Krabbe (Crab) members. The extent of these members in the type and reference wells are shown in (Fig 4.46 , 4.47).Basal StratotypeThe base of the formation (and of the Akkar Member) is defined by a marked increase in gamma ray and neutron porosity logs, but often more moderate increases in interval transit time and bulk density readings.
The middle Reke Member is characterized by a lower gamma ray response, but its base can be best defined by a carbonate bench above which the separation between density and porosity logs decreases markedly. This separation increases again at the base of the uppermost Krabbe Member . A characteristic feature of the Reke and Krabbe members are funnel-shaped gamma ray responses.Lateral extent and variationNo marked trends in lateral variation are suggested by present data, although few wells have yet penetrated the entire formation; the thickest sequence (262 m) is seen in well 7120/9-2 . The unit may be represented in its entirety further to the north in the Hammerfest Basin by the more shaly marine lithofacties of the Akkar Member passing up into sands of the overlying Tubåen Formation .AgeThe base of the formation is early Norian. The top corresponds in general to the Triassic/ Jurassic transition, but available data indicate that it is somewhat diachronous.Depositional environmentOpen marine shales of the Akkar Member pass up into coastal and fluvial sandstone dominated sequences of the Reke Member . These represent northward fluviodeltaic pro-gradation with a depocentre to the south. As the main deltaic input shifted laterally, most of the central and southern parts of the basin became the site of flood-plain deposition, with more marine environments to the north.SubdivisionPresent information suggests subdivision into three members as described above.Source-
Dalland, A., Worsley, D. and Ofstad, K. (eds.) 1988: A lithostratigraphic scheme for the Mesozoic and Cenozoic succession offshore mid- and northern Norway. NPD-Bulletin No. 4, 65 pp.
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Wellbores penetrating
Wellbores penetrating 25.09.19843185324826.06.19811855190217.02.20112808291715.11.1985692110626.12.1985692110621.07.1986692110628.03.19892506263007.10.2013689110109.07.20112363256306.06.19852648270022.07.20072886314521.08.19832435252310.09.19812462261029.07.19822455259010.12.20072643269726.09.19822077217320.10.19842290255208.09.19841914200012.10.19802337253511.09.19812234235405.05.19832395252303.01.20112407258213.11.198569879223.08.198669879227.10.19842532260914.04.19852737280028.09.19852572279306.07.19862503254309.03.20012034222305.08.19842045216012.08.19862073215615.07.20172039208013.01.19922464263511.11.19872063219119.09.20062113220210.10.20211921201505.10.20001125120219.10.20011196130325.11.20061177124423.12.20061181128113.01.20071218128604.01.20131122120826.12.20181274130628.09.201762069714.05.20082141225921.04.20082139226620.10.19871305143812.10.20111312133030.12.19881521161207.03.2007882100201.12.2008930102608.01.201661262613.05.200588396009.02.201972077907.04.201977987830.09.20133283342525.02.19882305287729.07.20201069133819.01.20171653216928.02.20171907202607.11.20172000210017.01.20182651275010.10.20141113153825.02.20142513299024.03.20121695174026.10.20181692178224.01.20122130223016.12.20131190176905.05.20141858209702.05.20111628212222.05.2022997135007.06.20221288130916.10.20121931230325.05.201852557004.11.200858963627.02.201462867214.01.200954058504.03.201670578321.08.20081064116619.06.1988931102825.09.201177080407.08.201379080719.07.2008950105211.04.19881234129610.11.20141675190926.04.20121034113720.12.19891404152302.02.20011494164210.02.20011494164208.01.20011480159807.05.19901140123215.12.19931323145307.10.20171079121901.10.20181369150622.10.19882039220703.09.19871467162601.07.20201665172828.11.19881424157228.05.202171977618.06.201487189421.11.201890993831.07.201981185403.11.201379989606.07.201473683914.04.20161144137317.09.201373077216.05.201568378017.09.201768880507.08.201471276319.08.198957760621.07.201490595203.08.201779284015.06.201966580101.09.2017682780 -
Wellbores with cores
Wellbores with cores 28.03.1989511.11.19873510.10.2021605.10.20004325.11.20063204.01.20133728.09.20172420.10.198710407.03.20072413.05.20052925.02.19882619.01.20171916.12.201314722.05.2022919.07.2008211.04.19881403.09.19877731.07.20191106.07.20144617.09.20177407.08.20141103.08.201726