RP riser platform (Ekofisk 2/4 G)
The History
But the existing 2/4 R riser platform at the Ekofisk centre was not strong enough to take the extra pipelines carrying oil and gas from Valhall and Hod. A new structure was required.
To speed things up and achieve a relatively low-cost solution, Amoco’s Asbjørn Tansø proposed copying the jacket supporting the quarters platform – the smallest of Valhall’s installations.
That approach was approved by the Norwegian Petroleum Directorate (NPD), and Ekofisk operator Phillips Petroleum Company Norway undertook to run the platform for a fee.[REMOVE]Fotnote: Rasen, Bjørn (2007): LF6A. Valhall at 25 … and it’s only the beginning , 72.
Aker Verdal built the module support frame for this Ekofisk 2/4 G facility and a bridge to carry piping systems to the Ekofisk tank, known as 2/4 T. Heerema/Seaway was the main contractor for the steel jacket, with DeGroot as the fabricator.[REMOVE]Fotnote: Kostnadsanalysen norsk kontinentalsokkel , volume II, 277.
The platform was installed in 1981 and became operational the following year. Two pipelines, each 36.8 kilometres long, for oil and gas respectively were laid from the Valhall process and compression platform (PCP) to 2/4 G. From there, the oil was piped on via the Ekofisk facilities to Teesside in the UK while the gas travelled to Emden in Germany.
As part of a major conversion project on Ekofisk in 1998, the transport system was restructured and 2/4 G ceased operation. Its bridge to the Ekofisk tank was removed in 2014, and plans call for topsides and jacket to be dismantled in a few years time.
Technical details
The steel jacket was 90 metres tall, had four legs and weighed 2 600 tonnes – including the piles holding it to the seabed. With modules, the topside came to 3 400 tonnes and measured about 35 x 21 x 10 metres. Topside equipment was integrated in the support frame, which carried no modules on top.[REMOVE]Fotnote: Kostnadsanalysen norsk kontinentalsokkel , volume II, 230. A large crane was positioned at the northern corner, and a bridge about 50 metres long ran to the Ekofisk tank.
Process
The platform was intended to receive and send on oil and gas from Valhall, which was merged with output from the Ekofisk area. Equipment was accordingly limited metering to facilities for monitoring and checking these flows.