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Factpages Norwegian Offshore Directorate
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11.12.2024 - 01:27
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FJERRITSLEV FM

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  • General information

    General information
    Attribute Value
    Lithostrat. unit
    The lithostratigraphic unit's official name.
    FJERRITSLEV FM
    NPDID lithostrat. unit
    Norwegian Offshore Directorate's unique id for lithostratigraphic units.
    42
    Level
    Indicates the lithostratigraphic unit's level. Legal values: GROUP, FORMATION, MEMBER.
    FORMATION
    Lithostrat. 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

    Fjerritslev Formation

    Name
    After the village of Fjerritslev, Jutland, Denmark, (Larsen, 1966)
    Well type section
    Fjerritslev No 2 well, Jutland, (Larsen 1966).
    Well reference sections
    In Norwegian waters wells 17/9-1 R (Esso) from 2835 m to 2992 m, coord N 58°28'27.26", E 03°50'16.18" (Fig 3.25) . and 7/9-1 (Conoco) from 2524 m to 2601 m, coord N 57°20'37.10", E02°51'21.4" (Fig 3.24) .
    Thickness
    In the Norwegian reference wells the thickness of the Fjerritslev Formation is 157 m ( 17/9-1 R ) and 77 m ( 7/9-1 ).
    Lithology
    The formation consists predominantly of grey to dark grey or greyish brown marine claystone. It is variably calcareous and pyritic. Silty intervals occur frequently, grading into grey or buff micaceous siltstone. In the Danish area the Fjerritslev Formation is divided into four members according to degree of siltiness (Michelsen, 1978). However, such a subdivision is not merited in the Norwegian sector.
    Boundaries
    The formation is distinguished from the underlying sandy deposits of the Gassum and Skagerrak formations, and from the overlying sands of the Vestland Group , by its higher gamma ray and lower sonic log velocity readings.
    In reference well
    17/9-1 R the Fjerritslev Formation is overlain by a sequence of interbedded lavas and sediments over 500 m thick which are probably of Lower-Middle Jurassic age. This sequence has only been identified in one well. The boundary between the Fjerritslev Formation and the volcanics is again made by an upward change to lower gamma ray readings and higher sonic log velocities, (Fig 3.25) .
    Distribution
    The Fjerritslev Formation is only patchily developed in the Norwegian sector. The developments which are present probably represent those remnants of a once more widely distributed deposit which survived the mid-Jurassic erosional episode. The formation has been penetrated in two distinct and separate areas; around the Southern Vestland Arch (e.g. blocks 7/9 and 7/12) and in the Egersund Sub-Basin (e.g. block 17/9).
    Age
    The formation ranges in age from Hettangian to Pliensbachian. It is approximately equivalent to the Lower Jurassic Dunlin Group of the Northern North Sea, although no direct connection between the two sequences is thought likely.
    In reference well
    17/9-1 R a dyke immediately below the Fjerritslev Formation has been dated as Pliensbachian (Fumes et al., 1982).
    Depositional environment
    The claystones of the Fjerritslev Formation are shallow marine sediments deposited during a widespread marine transgression.
    Remarks
    In block 17/12 (Bream area) a sequence of continental clastics has been dated as Pliensbachian to Toarcian (Olsen and Strass, 1982). They are therefore partially age-equivalent to the Fjerritslev Formation, but cannot on lithological grounds be referred to the latter, (Table 3.4). These deposits have not been named by the present nomenclature group.
    Source
    • Vollset, J. and Doré, A. G. (eds.) 1984: A revised Triassic and Jurassic lithostratigraphic nomenclature for the Norwegian North Sea. NPD-Bulletin No. 3, 53 pp.
  • Wellbores penetrating

    Wellbores penetrating
    Wellbore name
    Wellbore completion date
    Top depth [m]
    Bottom depth [m]
    29.05.1971
    2524
    2601
    07.06.1981
    3901
    3917
    28.04.1987
    3601
    3685
    21.09.1987
    3475
    3498
    09.12.2005
    3068
    3118
    07.02.2011
    2726
    2800
    11.06.1974
    2835
    2992
    10.07.2009
    2398
    2439
  • Wellbores with cores

    Wellbores with cores
    Wellbore name
    Wellbore completion date
    Core length [m]
    07.06.1981
    12