29/9-1

General

Well 29/9-1 is located on the Hild structure ca 1.5 km west of the UK border on the eastern margin of the East Shetland Basin in the North Sea. The well was drilled to appraise the 30/7-2 discovery. The main objectives were to test the hydrocarbon prospectivity and reservoir parameters of the Middle and Early Jurassic sequence. The well was planned to be drilled 50 m into the Statfjord Formation at a total depth of 4640 +/- 200 m.

Operations and results

Appraisal well 29/9-1 was spudded with the semi-submersible installation Treasure Seeker on 23 September 1983 and drilled to TD at 4703 m in the Early Jurassic Statfjord Formation. During drilling of the 17 1/2" hole, tight hole problems were experienced. The 9 5/8" casing had to be run twice due to problems with the casing hanger seal. Due to high temperature and lack of circulation the mud in the 7" liner gelled up and had to be replaced several times. This caused difficulties operating the testing tool. The well was drilled with seawater and gel slugs down to 1057 m and with KCl/polymer mud from 1057 m to TD. Mud retort test showed 4-5% oil in the mud from top of the 12 1/4" section at 2752 m, declining to traces at 3732 m.

The well encountered oil in the Frigg Formation in the interval 1782 to 1787 m (OWC), and gas in the middle Jurassic Brent Group from 4386.5 m to 4421 m (gas down to top Dunlin Group; no hydrocarbon contact was encountered).

The Frigg Formation (1782-1981 m) consisted of predominantly of fine to coarse grained porous sandstones. The uppermost 2.5 m was tight and calcareous cemented. Net pay was thus 2.5 m with 31% average porosity and 40% average water saturation, based on logs. No