Eiriksson Formation (elevated)
(From NPD Bulletin no. 1)
Statfjord Group
Name
Named after Leiv Eiriksson, the discoverer of North America in
the year AD 1000, according to the Norse sagas. He was the son
of Eirik Raude.
Well type section
Norwegian well 33/12-2
(Mobil), from 2719 m (8919 ft) to 2790 m (9153 ft)
below KB.
Well reference section
UK well 211/24-1 (Conoco/Gulf/NCB).
Thickness
71 m (234 ft) in the type well. In the reference well the member is
157 m (514 ft) thick. The thickness is relatively constant over the
area of the Statfjord Field but the member thickens towards the south
and west (Figure 18) where sandstones characteristic of this member
occur at lower levels in the section.
Lithology
In the type well the formation is characterised by massive sandstone beds,
generally correlatable between wells, interbedded with hard grey
shales. The sandstones are white to light grey, medium to very coarse
grained with thin horizons of granules, pebbles, and lignite fragments,
often concentrated in channels and along cross-bedding foresets. They
contain slighly less kaolinite matrix, mica and rock fragments than the
sandstones of the Raude Formation. The shales are
silty and commonly micaceous and carbonaceous.
In the area of the Statfjord Field the sandstone beds average about 5 m
(16 ft) in thickness and the shales average about 2.5 m (8 ft). The
sediments of this formation appear more mature than those of the Raude
Formation, and marine fossils and glauconite are present near the top
of the member in the type well. The data suggest that deposition occurred
in marginal marine environments varying from coastal backswamp and
river mouth situations to coastal barriers.
Boundaries
The lower boundary is formed by the base of the lowest massive sandstone
which is correlatable between wells. The upper boundary is marked by
the base of the distinctive sandstones of the
Nansen Formation which are frequently calcareous. The Eiriksson
Formation has a characteristic 'blocky' gamma ray and sonic log response
but the boundaries may not always be marked by prominent log breaks.
Distribution
The formation can be recognised over an extensive area around the
Brent and Statfjord Fields.
Age
In the type well it is Hettangian, possibly extending into the early
Sinemurian. However, to the west and south the base of the member
appears to be progressively older.
