7222/6-1 S

General

The 7222/6-1 S Obesum well was drilled on the Bjarmeland Platform, south of the Swaen Graben, east of the Loppa High in the Barents Sea. The objective was to prove hydrocarbons in the Snadd Formation of Carnian age (B1 and B2 prospects) and in the Kobbe Formation of Anisian age (B3 and C4 prospects).

Operations and results

A pilot hole, 7222/6-U-1, was drilled 15 m east of the main well location. No shallow gas was found in the pilot hole. Wildcat well 7222/6-1 S was then spudded with the semi-submersible installation Polar Pioneer on 7 January 2008 and drilled to TD at 2895 m (2848 m TVD RKB) in the Early Triassic Havert Formation. The well was designed as an S-shaped well due to shallow gas warning, with a simplified casing design including a 30" casing at 452 m, a 20" casing set at 599 m and a 9 5/8" casing at 1050m. The 9 5/8" casing was set above the reservoir intervals that could have a pressure increase. At 1321 m the drill line snapped out of drum and DDM bails and elevator slid down maximum 1m and stopped on rig floor. Totally 6.2 days were lost to repairing of the damage done in this incident. The well was drilled with Seawater down to 604 m and with FormPro mud from 604 m to TD.

The Obesum well penetrated a short Quaternary section and then rocks of Triassic age. The observed stratigraphy was close to the prognosis, except for the reservoir levels in Snadd formation, which came in at 484 m (ditto TVD RKB), much shallower than expected. The Kobbe Formation came in at 1890 m (1843.2 m TVD RKB). Hydrocarbons were proven in channelized sandstones of Ladinian age (Snadd Formation) and in thin sandstone stringers in the Kobbe Formation. Moveable hydrocarbons were proven in this interval by MDT sampli