Ness Formation (elevated)
(From NPD Bulletin no. 3)
Brent Group
Name
Named by Deegan and Scull (1977) who gave it "sub-unit" status.
Well type section
UK well 211/29-3 (Shell), from 2633.5 m to 2772 m, coord N 61°08'06", E 01°43'36.5", (Fig. 10).
Well reference sections
Norwegian wells 33/9-1 (Mobil), from 2509 m to 2575 m, coord N 61° 15 '07.5" E 01°50'25.8", (Fig. 11), 30/6-7 (Norsk Hydro) from 2646 m to 2727 m, coord N 60°38' 39.49" E 02°45'21.74", (Fig. 16), and 31/4-4 (Norsk Hydro) from 2695 m to 2721 m, coord N60°40'01.12", E03°06'54.12",(Fig. 17).
Thickness
138.5 m in the type well, 66 m in 33/9-1, 81 m in 30/6-7 and 26 m in 31/4-4.
Lithology
The formation consists of an association of coals, shales, siltstones and very fine to medium grained sandstones. The formation is carbonaceous throughout and contains numerous rootlet horizons. Small scale cross-bedding and horizontal bedding are common. Synsedimentary deformation is frequently observed. The shales are silty, fissile and frequently pyritic. The formation occasionally shows some marine influence. Coarsening and fining upward sequences are common features. The varied lithology produces an irregular but distinctive gamma ray and sonic response.
Boundaries
The lower boundary defines the top of the Etive Formation. The upper contact is marked by the change to the more massive cleaner sandstone of the overlying Tarbert Formation. This upper contact may be a minor disconformity.
Distribution
The distribution of the Ness Formation is essentially the same as that of the Brent Group.
Age
Bajocian.
Depositional environment
The formation is thought to represent delta plain or coastal plain deposition.
