2/2-3

General

The wildcat 2/2-3 was drilled on a domal structure, south of the Ula-Gyda fault zone. Main objective was Late Jurassic sandstone in the Vestland Group. Secondary target was Middle Jurassic and Late Triassic sandstones.

According to the license agreement the well should be drilled into the Triassic, salt, or a maximum depth of 5000 m whatever came first

Operations and results

The well was spudded with the semi-submersible rig Treasure Saga on 4 February 1983 and drilled to TD at 4100 m, 170 m into the Triassic Smith Bank Formation. At 3286 m the string was lost after a wiper trip. The well had to be plugged back to 3053 m and sidetracked from this point. At 3420 m the string was again lost but was recovered. The well was drilled using water-based mud. The well was drilled with seawater and bentonite down to 655 m, with polymer/gypsum/"SST 202" mud from 655 m to 1910 m, with lignite/Drispac/gypsum mud from 1910 m to 3523 m, and with lignite/lignosulphonate mud from 3523 m to TD.

The well penetrated 2998 m of Cenozoic sediments represented by the Nordland, Hordaland and Rogaland Groups. The sequence was mainly composed of argillaceous deposits. The Oligocene Sand Unit (Vade Formation) recognized in well 2/2-1 and 2/2-2, was not established in this well. The Cretaceous sequence consisted of two lithostratgraphic units, the Chalk and Cromer Knoll Group. They were separated by an unconformity ranging from Santonian to Middle Albian. The Early Cretaceous and upper part of the Late Jurassic (Ryazanian-Middle Volgian) are highly condensed. The Late Jurassic predominantly consists of claystones of the Mandal (4m) and Farsund Formations. The Ula Formation is present from 3880 m in the bottom part of the Late Jurassic as a sandstone sequence of Early Kimmeridgian - Late Oxfordian age. The formation is resting unconformably on sediments of the Triassic Group.

The Shetland Group chalk, 2965 m to 3494 m, has