15/9-10

General

Wildcat well is located between the Sleipner Vest and Sleipner Øst Fields. The well was designed to test possible hydrocarbon accumulations in the Upper Middle Jurassic sands and secondary test Heimdal Formation Sand of Paleocene age.

Operations and results

Wildcat well 15/9-10 was spudded with the semi-submersible installation Neptuno Nordraug on 15 September 1981 and drilled to TD at 3289 m in the Triassic Smith Bank Formation. Drilling the 26" hole section complete loss of returns occurred at 186 m and a cement plug was set. Drilling out of the cement returns were again lost, at 178 m, requiring a further cement plug. Total losses due to this loss zone were well in excess of 10 000 bbls. After this operations went without significant problems. The well was drilled with seawater and hi-vis pills down to 172 m. The next section, the 26" section, was drilled down to 472 m with seawater/bentonite and quantities of Mica Fine, Nutplug, Kwikseal, and other additives. From 472 m to TD m the well was drilled with polymer/Drispac.

The well encountered Tertiary sands in the Utsira Formation at 884 - 1102 m, Grid Formation at 2049 - 2079 m, Heimdal and Ty Formations at 2547 m to 2667 m. An RFT run in the Heimdal sand indicated a water gradient, 1.02 g/cm3. The primary target Jurassic sandstones was encountered at 3070 m in the Hugin and Sleipner Formations. Some shows were recorded in the Hugin Formation, but from the logs the formations were all water-wet. Possible source rocks were encountered in a comparatively thick and marly Blodøks Formation from 2871 m to 2924 m, and in the Late Jurassic Draupne and Heather Formations from 3004 m to 3070 m. Four conventional cores were cut. Core 1 was cut from 3061 m to 3062.4 m in the Heather Formation, core 2 was cut from 3082 m to 3100 m in the Hugin Formation, and cores 3 and 4 were cut from 3137 m to 3171 m in the Sleipner Formation. No fluid sample was taken.

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