24/9-3

General

Exploration well 24/9-3 was drilled by Conoco for the Conoco/Statoil/Norsk Hydro/Hudbay PL 039 partnership. The well lies in the west-central part of block 24/9, close to the Norway/UK median line. The location was chosen to test an apparent sand build-up, observable on seismic lines, in the Lower Tertiary part of the section. The sand build-up was thought to correspond to the Lower Eocene Frigg Sand Formation, which forms the reservoir in the Frigg Field.

Operations and results

Well 24/9-3 was spudded with the semi-submersible installation SEDCO 704 on 28 January 1981 and drilled to TD at 3051 m in the Late Cretaceous Jorsalfare Formation. The duration of the well was 81 days, 20 of which were spent testing. A 36" hole was drilled to 207.6 m / 681 ft and 30" casing set to same depth. A 17 1/2" pilot hole was drilled to 518.2 m, logged, and then opened to 26". 20" x-56 casing was set at 503.2 m. A 17 1/2" hole was drilled to 1600.2 m, logged, and 13 3/8" N-80 casing was set at 1587.1 m. A 12 1/4" hole was drilled and cored to 2049.8 m, logged, and 9 5/8" N-80 casing was set then drilled to TD and logged. The well was drilled with spud mud to 518 m, with Dextrid/gel from 518 m to 853 m, with gel/lime from 853 m to 1067 m, with seawater/gel/Dextrid from 1067 m to 1600 m, and with seawater/lime/Dextrid mud from 1600 m to TD.

The Lower Eocene sands (Frigg Formation) were encountered 141 m high to prognosis at 1739 m. This shows that the sands correspond to a higher and less distinct build-up on the seismic. The build-up originally mapped corresponded to the Paleocene Tuff level and contained shales and water-wet Paleocene Sands. A gross interval of 92 m of Early Eocene Sands was penetrated. The uppermost 70 m, from 1739 m, were hydrocarbon bearing down to an OWC at 1809 m, while the lowermost 22 m (1809-1831m) were water bearing. Patchy oil shows were observed down to 1870 m, no sho