15/9-18

General

Well 15/9-18 is located between the Sleipner Øst and Sleipner Vest Fields in the South Viking Graben in the North Sea.

It was designed primarily to test hydrocarbon accumulations in the Middle Jurassic Hugin Formation. Secondary objectives were Paleocene sandstones in the Heimdal and Sleipner Formations, and sandstones of Triassic age.

Operations and results

Wildcat well 15/9-18 was spudded with the semi-submersible installation Deepsea Bergen on 16 December 1983 and drilled to TD at 3622 m in the Triassic Smith Bank Fm. No major problems occurred while drilling this well, but some tight hole problems were experienced in the 12 1/4" hole section. The well was drilled with seawater gel down to 520 m and with gypsum/lignosulphonate mud from 520 m to TD.

Tertiary sands were penetrated at 866 m (Utsira Formation), 1254 m, and at 2071 m ("Frigg Fm Equivalent"). The Draupne Formation was encountered 105 m thick at 3108 m. The Hugin Formation was encountered at 3237 m. It was found hydrocarbon bearing in a 7.5 m interval from 3237.5 m and down to a coal layer at 3245.0 m but the hydrocarbons were immovable. The well did not encounter other hydrocarbon bearing intervals. Shows were however recorded further down in the Hugin Formation in the interval 3275 m to 3325 m.

Four cores were cut, two in the Paleocene and two in the Middle Jurassic sequence. Segregated FMT fluid samples were taken in the hydrocarbon bearing interval in the Hugin Formation at 3238.3 m, 3239 m, and 3240 m. All samples were reported to recover mud filtrate only, but the samples from 3240 m were analysed to contain 0.2 g petroleum hydrocarbons.<