2/11-1

General

Exploration well 2/11-1 is located on the southern periphery of the Valhall Field in the North Sea. The objective of this early wildcat was to test all horizons down to the Rotliegendes, estimated at 14100 ft (4298 m). Top Permian was expected at 10300 ft (3139 m). Planned TD was at 15000 ft (4572 m).

The well is Reference Well for the Åsgard, Sola, and Rødby Formations.

Operations and results

Well was spudded with the semi-submersible installation on and drilled to TD at 4691 m in the Late Jurassic Tyne Group. The well started to build angle from below ca 3500 m with maximum 11 deg deviation at 4444 m. Otherwise no significant drilling problems were reported from this deep well. The well was drilled water based down to 3432 m and with an invert oil mud (Vertoil) from 3432 m to TD.

Top Paleocene, Balder Formation, was encountered at 2590 m. Top chalks of the Shetland Group (Tor Formation) was encountered at 2635 m. In addition to shows from the gas detector, free oil was seen floating on the mud pits and samples showed good fluorescence and cut through the interval 2585 m to 2633 m (Balder, Sele, and Lista Formations). Post-well geochemical analyses reported significant oil staining down to 2776 m. By testing live oil was confirmed in the uppermost Tor Formation. The tests were inconclusive with regard to an OWC, but the logs indicated that the contact was at 2655 m. Base Cretaceous was at 3555 m. The well did not reach Permian sediments; in stead the well drilled 1136 m in Late Jurassic shale (Mandal, Farsund and Haugesund Formations) before final TD was set. One conventional core was cut from 3864 to 3878 m in the Farsund formation.No wire line fluid samples were taken.

The well was permanently abandoned on 3 October 1969 as a minor discovery. After the 2/8-6 Valhall Discovery well was drilled 6 years later well 2/11-1 was re-classified to oil appraisal well for the Valhall Field.

Test