Egersund Formation

(From NPD Bulletin no. 3)

Boknfjord Group


Named by Deegan and Scull (1977) who gave the unit member status.

Well type section

Norwegian well 9/4-1 (Amoseas) from 2251 m to 2288 m, coord N 57°35'02", E 04°01'13" (Fig. 34, NPD Bulletin no. 3).

Well reference section

17/12-1 (Phillips) from 2215 m, to 2290 m, coord N58°ll'15.4", E03°56'22.2" (Fig. 35, NPD Bulletin no. 3).


37 m in the type well and 75 m in the reference well.


In the type well the formation consists of dark grey micromicaceous shales and siltstones with brownish, locally oolitic, microcrystalline carbonate beds and occasionally sandstone streaks. The latter become more important east and north-east of the type well.


The lower boundary is also the junction of the Boknfjord Group with the Vestland Group and is described above. At the base of the formation a more radioactive part is recognizable in several wells. The upper boundary is marked by the appearance of the dark grey to black organic-rich shales of the overlying Tau Formation. The shales of the Tau Formation have a high radioactivity and a low velocity, and therefore the upper boundary is marked by strong log breaks.


The formation is distributed throughout the Fiskebank and Egersund Sub-Basins.


Callovian to Kimmeridgian.

Depositional environment

The Egersund Formation was deposited in an open marine, generally low energy basinal environment.

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