16/1-8

General

Well 16/1-8 was drilled on the Luno Prospect on the eastern margin of the South Viking Graben on the south-western part of the Utsira High in the North Sea. The Luno prospect is situated between well 16/1-5 with oil shows in Late Jurassic and 16/1-4 with gas/condensate discovery in fractured basement rocks and up dip from the 16/1-7 Jurassic discovery. The primary objective of well 16/1-8 was to test the hydrocarbon potential in Late Jurassic sandstones of the Viking Group. Secondary objectives were to assess the quality of the Eocene Grid Formation and Permo-Triassic sandstones. Total depth was planned in basement at 2173 +/- 50 m.

Operations and results

Well 16/1-8 was spudded with the semi-submersible installation Bredford Dolphin on 8 September 2007 and drilled to TD at 2200 m in undefined Triassic formations consisting of conglomerates, sandstones and claystone. A shallow gas zone was warned and encountered in a thin sand from 634 - 638 m. Downtime (NPT) for the operations was as much as 33% of total rig time. Forty-four per cent of the total NPT was due to WOW before anchor handling. Another 14 % of NPT was caused by problems with cementing the 13 3/8" casing. In addition formation characteristics in the reservoir made operations challenging, and combined with increased formation evaluation scope; time spent on coring, logging and drilling to TD drastically increased compared to plan. The well was drilled with seawater and hi-vis pills down to 400 m, with KCl/glycol enhanced mud (GEM) from 400 to 1196 m, and with Performadril mud from 1196 m to TD. Performadril may contain up to 5% polyakylene glycols.

The Eocene sandstones of the Grid Formation at 155