34/4-11

General

Well 34/4-11 was drilled north of the Snorre Field and ca two km northwest of the 34/4-10 R Brent oil discovery in the Marulk Basin in the Northern North Sea. The primary objective was to drill and evaluate the Beta central fault terrace to the northwest of 34/4-10 R. The Beta central fault terrace is situated on the same general structure as in 34/4-10 R, but on a different fault block. Secondary objectives were to evaluate the petroleum potential in the Early Jurassic Dunlin Group and Statfjord Formation.

Operations and results

Wildcat well 34/4-11 was spudded with the semi-submersible installation Songa Delta on 13 October 2009 and drilled to TD at 4327 m in Late Triassic sediments of the Lunde Formation. No significant problems were encountered in the operations. The well was drilled with seawater and hi-vis pills down to 1340 m, with Aqua-Drill mud containing 3.5 - 4.0 % glycol from 1340 m to 2293 m, and with Carbo-Sea oil based mud from 2293 m to TD.

A 51 m thick Brent Group (primary target) was encountered at 3969 m (3938.7m TVD MSL), 18.7 m TVD deep to prognosis. The Brent Group was oil-bearing, but reservoir quality was poor with only 7 m net. The poor reservoir properties resulted in no successful RCI pretests. The Dunlin Group was present as a marginal siltstone facies from 4020 to 4131 m. The Statfjord Formation came in at 4131 m (4100.7 m TVD MSL) with sandstones with oil shows and drill gas peaks with a full C1-C5 chromatograph breakdown. The Statfjord Formation was seen to be an interbedded sequence of sandstone, siltstone and claystone. The Statfjord reservoir was oil bearing down-to at least 4215.7 m (4185.3 m TVD MSL). Petrophysical analyses proved 85 m gross and 22.4 m net oil bearing Statfjord reservoir