30/9-22

General

Well 30/9-22 (Katla) was drilled on the edge of the Horda Platform in the northern part of the Viking Graben, south of the Oseberg Sør field. The objective was to prove the presence of commercial hydrocarbons in the Middle Jurassic Tarbert Formation and to collect all data needed to assess the development of the prospect.

Operations and results

Wildcat well 30/9-22 was spudded with the semi-submersible installation Polar Pioneer on 29 January 2009 and drilled to TD at 3255 m in the Early Jurassic Dunlin Group. No shallow gas was observed by the ROV at the wellhead or by the MWD while drilling the 26" hole or the 17 1/2" hole. No significant problems occurred in the operations. The well was drilled with seawater and CaCl2 /polymer down to 339 m and with Glydril water based mud from 339 m to TD.

The well penetrated rocks of Quaternary, Tertiary, Cretaceous, and Jurassic age. The Heather Formation (Intra-Heather Formation Sandstone) was encountered at 2828 m, 44 m shallower than prognosed. The Tarbert Formation was encountered at 2866 m, 55 m shallower than prognosed. The Intra Heather Formation sandstone was gas filled, and the Tarbert Formation sandstone contained both gas and oil. Pressure measurements indicated a higher gas gradient and a pressure regime that was ca one bar lower in the Intra-Heather reservoir compared to the Tarbert Formation. The Tarbert Formation had a gas-oil contact at 2874 m and an oil-water contact at 2911 m. No oil shows were recorded outside of the target reservoir sections.

Two cores were cut; the first one started in the Heather Formation and continued in the Tarbert Formation, core #2 was cut in the Tarbert Formation only. MDT fluid sa