Egersund Formation
(From NPD Bulletin no. 3)
Boknfjord Group
Name
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).
Well reference section
17/12-1 (Phillips)
from 2215 m, to 2290 m, coord N58°ll'15.4", E03°56'22.2" (Fig. 35).
Thickness
37 m in the type well and 75 m in the reference well.
Lithology
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.
Boundaries
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.
Distribution
The formation is distributed throughout the
Fiskebank and Egersund Sub-Basins.
Occurrences of formation tops in wells
Age
Callovian to Kimmeridgian.
Depositional environment
The Egersund Formation was deposited in an open marine, generally low energy basinal environment.
