6407/5-2 S

General

Well 6407/5-2 S was drilled on the eastern side of the Gimsan Basin on the Halten Terrace in the Norwegian Sea. Nearest discoveries are the Mikkel Sør gas wells, 2-3 km to the east. The main objective of the well was to drill and evaluate the Late Cretaceous Lysing Formation in the Chamonix Prospect. The deeper Jurassic reservoirs of the Garn, Ile, Tofte and Tilje Formations were seen as secondary targets.

Operations and results

Due to presence of cold water corals and sponges in the region, identified during the site survey, the spud location for Chamonix was moved 500m SE from its original planned position. This prevented any negative effects on the cold-water corals and sponges during anchor laying and drilling operations. In order to penetrate all targets vertically, the well was drilled with an S-shaped trajectory.

Wildcat well 6407/5-2 S was spudded with the semi-submersible installation Borgland Dolphin on 28 July 2011 and drilled to TD at 3545 m in the Early Jurassic Tilje Formation. Due to potential shallow gas a 9 7/8" pilot hole was drilled from 332 m to 545 m. No shallow gas was observed. No significant problem was encountered in the operations. The well was drilled with spud mud down to 545 m and with Carbo-Sea synthetic oil-based mud from 545 m to TD.

No movable hydrocarbons were discovered in the prognosed Late Cretaceous Lysing Formation. Post-well biostratigraphic evaluation of the well assigned these sand intervals to the Lange Sandstone Member. A non commercial gas discovery was made in Jurassic sandstones where a ca 40 m gross gas column was penetrated from top Rogn Formation at 3109.5 m (2986.4 m TVD), through a thin Melke Formation sandstone and