7120/12-5

General

Well 7120/12-5 was drilled on the Lunde prospect next to the 7120/12-3Alke North discovery in the Hammerfest Basin of the Barents Sea. The main targets were the Stø Formation sandstones in the top of the Kapp Toscana Group, Intra Carnian sandstones of the Snadd Formation and Kobbe Formation sandstones. These formations were expected to be gas bearing.

Operations and results

Wildcat well 7120/12-5 was drilled with the semi-submersible installation Polar Pioneer. Drilling started on 3 January 2010 with a 9 7/8" pilot hole 51.5 m from the main well position to check for shallow gas. No shallow gas was observed. The rig was then moved to the planned position, where it was spudded and drilling commenced to 1761 m where the initial 16" hole was abandoned owing to hole instability. A new 16" hole was sidetracked from 533 m and drilling then proceeded without significant problems to final TD at 3630 m in the Middle Triassic Kobbe Formation. The well was drilled with Seawater and hi-vis sweeps down to 510 m, with K-Format mud from 510 m to 1761 m in the primary well bore and to 1591 m in sidetrack, and with KCl/GEM/Polymer mud from 1591 m to TD.

Sandstones of reservoir quality were penetrated in all three targets, but all were found to be water wet. Based on 12 valid XPT-MDT pressure points a water gradient of 0.101 bar/m was established from the Stø Formation at 2150 m to the Snadd Fm (Intra Carnian sand) at 3100 m. The Stø Formation was encountered at 2165 m, 26.5 m higher than originally prognosed. The Stø sandstones were generally very fine to fine, well sorted and poorly cemented with occasional kaolinite matrix. Top Snadd Formation was encountered at 2582 m with the secondary target Intra Carnian sandstones a