2/6-3

General

Well 2/6-3 is located on the north western flank of the Mandal High between the Søgne Basin and the Central Graben in the North Sea.It was drilled to test possible hydrocarbon accumulations in Late and Middle Jurassic sandstones. A third objective was to reconnoitre below base Permian.

Operations and results

Wildcat well 2/6-3 was spudded with the semi-submersible installation Byford Dolphin on 9 November 1982 and drilled to TD at 4060 m, 270 meter into pre-Late Devonian basement rock. Technical problems occurred in the 12 1/4" section due to twist-off of Kelly saver, loss of 2700 m logging cable in hole, and 9 5/8" casing hanger collapse, causing a total of 203 hrs lost time. In the 8 1/2" section an anchor chain parted during a storm and four days were lost waiting on weather and re-anchoring. The well was drilled with water based mud.

In the Late Jurassic only marine shales were encountered. At 3545 m, 200 m higher than prognosed a Middle Jurassic, fluvial sandstone of Bajocian age (Bryne Formation) was found water bearing. A sequence of anhydrite, dolomite and pure anhydrite was found below the Triassic red-shales, but no salt or Rotliegendes reservoir rocks were encountered. The Permian anhydrite was followed by a series of slated shales and phyllitic rocks, getting progressively more and more deformed, and with an introduction of metamorphism towards TD. Rb-Sr dating on 1-micron fraction material from 3875 m gave an age of 376 Ma in the Late Devonian. No oil shows were reported from the well. Background gas was recorded down to top Permian. No gas was recorded below top Permian.

Three cores were cut. K1was cut at 3551 - 3560 m in Bryne Formation sandstone with 85% recovery. K2 was cut at 3886 - 3895 m in basement rock with 11% recovery (one meter, presumed to be from the top of the interval), and K3 was cut in basement at TD with 58% recovery. RFT pressure points were obtained but no wire l