30/9-23

General

The 30/9-23 Quest well was drilled on the Bjørgvin Arch in the Northern North Sea, between the Oseberg, Oseberg Sør, and the Brage Fields. Four reservoir levels were expected, the Intra Draupne sands, Sognefjord Formation, Fensfjord Formation and Brent Group sands. The main objective of the 30/9-23 well was to prove a commercial hydrocarbon accumulation in any of these levels.

Operations and results

Wildcat well 30/9-23 was spudded with the semi-submersible installation Transocean Winner on 28 July 2009 and drilled to TD at 2873 m in Early Jurassic sediments of the Dunlin Group. A 9 7/8" pilot hole was drilled below the 30" casing from 189 m to 510 m. The hole was opened to 17 1/2" and drilled down to 1007 m before setting the 13 3/8" casing. Returns were to seabed above 13 3/8" casing. No shallow gas was observed by the ROV at the wellhead or by the MWD while drilling the 36" hole, the 9 7/8" pilot hole, and the 17 1/2" hole. The well was drilled with seawater and bentonite sweeps down to 1003 m, and with Glydril mud from 1003 m to TD.

The geological prognosis was relatively accurate. The Base Cretaceous Unconformity, top Draupne Formation, was penetrated at 2214 m. A thin Draupne sand was encountered, although not of the quality expected. Sognefjord sand was present as prognosed. Fensfjord sand was encountered at prognosed depth, but the interval was thicker and more fine-grained than expected. Brent was found as prognosed. The well proved a dry Quest prospect, in all 4 reservoir levels. The pressure measurements showed water gradients in all reservoirs. In the Fensfjord Formation no pressure measurements could be achieved, due to tight formation. Brent was depleted with 50 bars, mo