30/5-3 S

General

Well 30/5-3 S was drilled on the Corvus prospect in the northern part of the Viking Graben at the edge of the Horda Platform in the Northern North Sea. The objective of the well was to prove commercial amount of hydrocarbons in the prognosed Statfjord Fm in the Corvus prospect and to collect all data needed for development of the prospect. Well 30/5-3 S would also serve as kick-off well for a geological sidetrack to a Cretaceous target in the Corvus structure.

Operations and results

Wildcat well 30/5-3 S was spudded with the semi-submersible installation Transocean Winner on 6 February 2009 and drilled to TD at 4335 m (3863 m TVD) in Triassic shales of the Teist Formation. No shallow gas was observed by the ROV or by the MWD while drilling the 36" hole and the 26" hole. The well was vertical down to ca 2550 m and drilled deviated from there to TD. No significant problems were encountered in the operations. The well was drilled with seawater and bentonite sweeps down to 205 m, with seawater/ bentonite sweeps/ Glydril from 205 m to 1004 m, with Glydril mud from 1004 m to 2335 m, and with Versatec oil based mud from 2335 m to TD.

The well penetrated the Triassic at 3396m MD, at the prognosed Jurassic target depth and proved more erosion than expected in the area. The expected Jurassic sediments of the Statfjord Formation were not present; instead the formations of the Hegre Group were encountered directly below the base Cretaceous unconformity. Wire line logs proved a gas bearing interval throughout the drilled Triassic interval with no indication of a GWC encountered. Weak oil shows were recorded in the Triassic sands; otherwise no shows were reported from the well.

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