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NORLEX


Frigg Member

Hordaland Group, Horda Formation

Name

English/ Norwegian

Frigg Member / Friggleddet

Derivatio nominis

Named by Deegan & Scull (1977) after a Norse goddess, the wife of Odin.

Original definition

Deegan, C. E. & Scull, B. J. 1977. A standard lithologic nomenclature for the Central and Northern North Sea. Institute of Geological Sciences Report 77/25. Norwegian Petroleum Directorate Bulletin 1, 33 pp.

Lithology

The formation consists of sandstones with some lenses and streaks of silty claystone. The sandstones are poorly consolidated, light brown to buff, micaceous and carbonaceous, and very fine to medium, occasionally coarse grained. Some layers have a calcareous cement. Traces of glauconite are present. The silty claystones are green to grey and carbonaceous.

Thickness

The member has a thickness of 279 m in the type well and 140 m in the reference well. A depocentre with a maximum thickness of approximately 300 m lies in Norwegian block 25/1.

Geographical distribution

The Frigg Member is found in the southwestern part of quadrant 30, the northwestern part of quadrant 25, and in adjacent areas in the UK sector. The Frigg Member sands of the Beryl and Bruce Fields just extend into the Norwegian sector at about 59°30'N.

Occurrences of member tops in wells

Isochore map BALDER-FRIGG

Type well

Well name

25/1-1 .

Location

WGS84 coordinates:
UTM coordinates:
UTM zone:

Drilling operator name

Completion date

Interval of type section (m)

In 25/1-1 the member is from 2115 to 1836 m.

Reference wells

Well name

30/7-6

Location

WGS84 coordinates:
UTM coordinates:
UTM zone:
24/12-2:
WGS84 coordinates:
UTM coordinates:
UTM zone:

Drilling operator name

Completion date

Interval of reference section (m)

From 1923 to 1783 m in reference well 30/7-6.

Boundaries

Lower boundary (basal stratotype)

The lower boundary normally shows a decrease in gamma-ray intensity and an increase in velocity from the Balder Formation into the Frigg Member (Fig. .).

Upper boundary (characteristics)

The top of the member is placed where the sandstones give way to light grey to brown, occasionally green claystone of the Hordaland Group. The boundary is seen on logs as an increase in gamma-ray response and a decrease in velocity (Fig……).

"Reference" seismic sections

Location of section

[figure]

Seismic section

[Colour figure]

Fossil events/zones dating the formation

Age

Early Eocene.

Correlations

[Graph]

Depositional environment

The Frigg Member was deposited as submarine fans, by gravity flows. The mode of deposition led to the formation varying in thickness over short distances. The source was the East Shetland Platform to the west.

Remarks

The Frigg Member here defined in the Norwegian sector is equivalent to the Frigg Sandstone Member in the UK sector.

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