Nansen Formation (elevated)

(From NPD Bulletin no. 1)

Statfjord Group


After the Norwegian polar scientist, explorer and statesman, Fridtjof Nansen.

Well type section

UK well 211/24-1 (Conoco/Gulf/NCB) (Figure 17) from 3112 m (10,209 ft) to 3158 m (10,361 ft) below KB.

Well reference section

Norwegian well 33/12-2 (Mobil), Figure 17.


46 m (152 ft) in the type well and 19 m (59 ft) in the reference well.


In the type well the formation consists of medium- to coarse-grained, fairly well sorted, homogeneous, white sandstones with a calcite cement and a subordinate kaolinite matrix. Occasional horizons with granules or pebbles are present. Carbonaceous material and mica are rare but glauconite is quite common. Thin shale beds containing marine fossils are present.

At the top of the formation, from 3112 m (10,209 ft) to 3135 m (10,283 ft) in the type well is a more prominent calcareous horizon defined informally as the calcareous sandstone bed. This may grade locally into a sandy limestone, for example, in the Brent Field.

The Nansen Member thins towards the east and passes laterally into calcareous siltstones and shales in the Norwegian sector (Figure 17). Although these siltstones and shales are lateral equivalents of the Nansen Formation they are placed in the overlying Dunlin Group on lithological grounds.


The lower boundary is marked by the change from the non-calcareous sandstones of the Eiriksson Formation to the cleaner, generally calcareous sandstones of the Nansen Formation. The upper boundary is marked by the change from calcareous sandstone to the argillaceous sediments of the Dunlin Group. Both boundaries are well marked on gamma ray and sonic logs particularly in the UK sector where the member is best developed. The calcareous sandstone bed at the top of the member is normally reflected by a distinctive sonic log response (Figure 17). However as this passes laterally into calcareous siltstones and shales the sonic log still responds to the calcareous nature of the sediments.


The formation is well developed in the Brent Field area. The lower part of the member overlaps westwards to the Cormorant Field area where it is probably the only representative of the Statfjord Group. The calcareous sandstone bed at the top does not extend as far west as the lower part of the formation.


Probably Hettangian to Early Sinemurian.

home previous page