7125/4-1

Wellbore history

General

Wildcat well 7125/4-1 was drilled on the Måsøy Fault Complex in the Barents Sea. The primary objective was to prove commercial hydrocarbon resources within the Nucula prospect, a 4-way structural closure dependent on sealing faults. The structure comprises the Middle Jurassic - Late Triassic Realgrunnen Group, the Late - Middle Triassic Snadd Formation and the Middle Triassic Kobbe Formation reservoirs.

Operations and results

Well 7125/4-1 was spudded with the semi-submersible installation Polar Pioneer on 17 January 2007 and drilled to TD at 1615 m in the Early Triassic Klappmyss Formation. The well was drilled without significant technical problems. It was drilled with sodium chloride brine down to 465 m and with potassium formate mud from 465 m to TD. No shallow gas was observed.

The Kapp Toscana Group, penetrated at 872 m, proved movable gas and oil in the Nordmela and Fruholmen Formations with a GOC at 894 m and an ODT at 939 m. Gas and oil samples were recovered at 951.8 m and 967 m respectively, suggest a separate reservoir at this level, but tight formation makes it difficult to evaluate, and these samples may represent a continuation of the reservoir above. The reservoir had a considerably poorer net/gross than expected. The underlying Snadd Formation was encountered at 1002 m. It was water bearing in the upper part where some sandstone intervals with very good reservoir quality were penetrated. Traces of oil and gas were described in the lower part of Snadd. The Kobbe Formation was encountered at 1206 m. It had a few good reservoir sandstones, especially in the upper part, and some residual oil was proven