Floating drilling units were first introduced in the USA in 1947, with the first well sunk from such a vessel in six metres of water by Kerr-McGee. This small independent oil company became the pioneer in offshore oil drilling. While exploration at sea was pursued only off the USA in 1956, it had spread to continental shelves worldwide by the middle of the next decade.
Norway’s Aker group joined forces with US company Drilling & Exploration Co in the summer of 1966 to establish contractor Sea Drill Associates. Converting the former factory vessel Thorshøvdi into a drill ship was proposed. Some promising model trials were conducted. The total investment would be only a third of that for competing rig types, and operating costs during drilling were also expected to be lower.
Thorshøvdi originally carried about 260 crew and factory workers, with two-berth cabins for the former and four-berth accommodation for the latter. The ship was equipped with a big laundry and washing facilities for personnel. Separate messes were provided for engine room and deck crew, craftsmen, junior officers, galley staff, whaler officers and crews, and factory workers. They had their own electric fridges.
Conversion was completed at Nylands Verksted in Oslo during the autumn of 1967, and the vessel was renamed Drillship. The ship would be able to carry with it much of the equipment and supplies otherwise shipped to drilling rigs by supply vessels, at a great saving in costs.
Aker expected that success with Drillship would give the company a competitive advantage in the fight for similar conversion assignments. Unfortunately, however, interest in the project waned quickly as people learnt of the problems this vessel encountered. A storm hit the Valhall area after less than a week’s drilling in late November 1967, and work had to be suspended.
A full hurricane blew up in the North Sea during mid-January, and Drillship’s mooring chains were snapped in two. The vessel had to spend several weeks in dock for reinforcements and improvements.
Once the vessel was back on the field, it ran into more bad weather. The upgrading work had clearly been of no benefit – half the mooring chains broke and the rest had to be cut.
It subsequently transpired that the well was less than 100 metres from the “black gold” when drilling had to stop because the anchors worked loose and the mooring system proved unable to keep Drillship in place in the rough weather.
The North Sea proved too tough for the old factory ship, which had served well for 17 years in the Southern Ocean, and it spent most of its time in port. But the vessel enjoyed some calmer years in the Mediterranean before ending its days at a scrapyard in Thailand during 1985.
Narve Sørensen/Thor-Glimt, DnV reg 1953, Tormod Ringdal og Oddvar Larsen
Tore Jørgen Hanisch/Gunnar Nerheim: Norsk oljehistorie bind 1, 1992
Bjørn Rasen: LF6A, 2007
Interview with A. Tansøe