35/12-2

General

Well 35/12-2 is an exploration well on the Grosbeak prospect. The Grosbeak prospect is located on the Ryggsteinen Ridge on the East flank of the Sogn Graben, with a number of fields and discoveries in the neighbouring blocks (Fram East, Fram West, Gjøa, Troll). The objective was to explore the hydrocarbon potential in sandstones of the Late Jurassic Sognefjord and Fensfjord formations and in the Middle Jurassic Brent Group.

Operations and results

Wildcat well 35/12-2 was spudded with the semi-submersible installation Songa Delta on 30 May 2009 and drilled to TD at 2541 m in the Middle Jurassic Brent Group. The well was drilled without significant operational problems and within pre-drill time schedule. The well was drilled with bentonite mud down to 517 m and with AQUACOL KCl/polymer mud from 517 m to TD.

The Late Jurassic Sognefjord Formation sandstones came in at 1968 m. Clear hydrocarbon shows and increased gas values were seen on penetrating this formation. The sandstones had an average porosity of 11.7 % when using a 10 % cut-off and contained gas to their base. The Heather Formation came in at 2030 m and consisted of very fine sandstones and siltstones with hydrocarbon shows throughout. Approximately 6 m of logs are missing in the top section of the Heather Formation. The Fensfjord Formation came in at 2100 m with oil encountered in a two-metre sandstone at the top of the formation. The Fensfjord Formation then passed into 13 m of shale, then into water-bearing sandstones. The sandstones had an average porosity of 19.4 % when using a 12.5 % cut off. Below the Fensfjord Formation was 291 m of non-hydrocarbon-bearing Heather Formation including 5 m of water-bearing Krossfjord Formation sandstone.

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