NC starts work on Statfjord C GBS
Norwegian Contractors (NC) began work on building the concrete gravity base structure (GBS) for Statfjord C on 10 November 1980, before the contract had officially been signed. The sheet pile retaining wall was re-established to be ready by 1 December, and notifications issued to shipping in the Gands Fjord. NC took the chance of starting up on its own account in order to provide work for personnel it wanted to retain.
The Statfjord B platform
Statfjord B is an integrated production, drilling and quarters (PDQ) platform which stands in 145 metres of water at the southern end of the field. The installation comprises a four-shaft Condeep concrete gravity base structure (GBS), built by Norwegian Contractors, and a steel topside assembled and outfitted by Moss Rosenberg Verft’s yard.
A discovery was made five kilometres north-east of the present site of Statfjord C in 1976, and another the following year 22 kilometres to the north. Dubbed the Statfjord satellites, their development represented a departure from the Condeep platforms used on the main field.
The Snorre licensees resolved in 1987 to develop this North Sea field with a tie-in to Statfjord for final processing, storage and export of the oil. On behalf of the partners in production licences 057 and 089, operator Saga Petroleum submitted a plan for development and operation (PDO) of Snorre to the Ministry of Petroleum and Energy that August. The proposed Snorre A production platform would have process facilities to part-stabilise the oil and gas through pressure and temperature reductions. Associated gas would be sold to the Statfjord group for use as fuel and to replace that field’s own production.
The Statfjord satellites
The Statfjord satellites is a collective term for three different reservoirs which have each been developed with their own solution, and tied back to the main field nearby. Statfjord North and East were developed as a single project, while Sygna forms part of the same licences as Statfjord East. The Statfjord north flank is regarded as part of the main licence. The satellites collectively increase reserves in the overall Statfjord area by about 15 per cent.
Geology and reservoir
The Statfjord reservoir lies 2 330-2 830 metres down, and measures six kilometres wide by 24 long. It comprises two large sandstone structures – the Brent group and the Dunlin formation – and a smaller one – the Statfjord formation.
The Statfjord C platform
Statfjord C is an integrated platform standing 5.5 kilometres north of Statfjord A. Built as a virtual copy of Statfjord B, it rests on a Condeep concrete gravity base structure (GBS) with four shafts. It began production on 2 July 1985.
Naming ceremony and an inconvenient rope
The Statfjord development was virtually over in 1984, and this was to be celebrated with the naming of the C platform by Crown Princess Sonja as the proud lady sponsor. Construction of this facility had gone entirely according to plan, without delays, cost overruns or accidents. But the ceremony was dogged with mishaps.
Building Statfjord C
The Statfjord licensees appointed an action team in the early summer of 1978 to assess possible options for building the planned C platform. Completed in 1979, this study concluded that none of the options on offer provided a financially acceptable solution.
Tow-out of Statfjord B
Statfjord B began its journey out to the field from the mating site at Vats north of Stavanger early on 1 August 1981. The world’s biggest tow to date moved silently through the darkness and rain clouds. The voyage began an hour ahead of schedule because the mooring chains were cut more quickly than expected.
“I name you Statfjord B …”
The weather in Stavanger on 17 June 1981 was misty and overcast, but the sun shone over the smooth sea at Vats further north. Early that morning, 60 guests had arrived there by sea for the naming of Statfjord B.
A giant mated
The last mooring was cut. That signalled the start to the tow of the concrete gravity base structure (GBS) for Statfjord B to Vats at 07.07 on 24 February 1981, one hour ahead of schedule.
The dispute over the loading buoy
The loading buoy for Statfjord B was to be built by the Aker group at its Tangen Verft and Vindholmen yards. Both had experience in platform building, with Vindholmen constructing the Beryl A topside for Mobil and both yards delivering modules to Phillips and Mobil.
Building the topside
Moss Rosenberg Verft (MRV) secured Norway’s largest industrial assignment until then when it was awarded the contract for building the topside for Statfjord B and for mechanical outfitting in the shafts of its concrete gravity base structure (GBS).
Building the concrete GBS
Statfjord B represented a new generation of Condeep gravity base structures (GBS). When built, it was the world’s largest human construction in history and much bigger than the Statfjord A concrete support structure.
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