2/8-3

General

Well 2/8-3 is located in the Feda Graben, ca 2 km north-east of the Valhall Field in the southern North Sea. The primary objective was to test the Jurassic hydrocarbon potential. The secondary objective was the chalk of the Shetland Group.

The well is reference well for the Haugesund and Farsund Formations.

Operations and results

Wildcat well 2/8-3 was spudded with the jack-up installation Zapata Explorer on 16 June 1972 and drilled to TD at 4115 m in Late Jurassic shales of the Haugesund Formation. The well took 48 days to complete and was drilled with unical/lignosulphonate/caustic based mud.

Reservoir quality rock was absent throughout the well. The first signs of oil were seen in Palaeocene tight siltstones with poor porosities. These were described as bright gold yellow fluorescence with a bright white streaming cut. Gas levels in the Shetland Group were low and no shows were seen in this group. A DST was run over part of this section but yielded only drilling mud. From 3267.3 m, within the Early Cretaceous, gas levels rose significantly and were associated with fair to poor shows in the Marls. The fluorescence was described as gold in colour with a slow pale yellow cut. From 3444 m, gas and shows increased and were contained in slightly argillaceous, hard limestone. Oil staining was seen and the fluorescence described as dark yellow gold with a pale yellow to very light brown cut. Mandal Formation shale was the first Jurassic age rocks seen. Gas levels were very high through these shales and the shows were described as bituminous with no direct fluorescence and a pale yellow cut. Between 3578 - 3600 m a gross sandstone unit was indicated by the gamma ray log. In rough