Phase I – first gas from Frigg

Gas flowed from the UK side of the field to TP1 and on through the British pipeline to St Fergus. Phase II, encompassing the platforms on the Norwegian side of the field, came on stream the following year. Plateau production from the whole field was achieved between 1980 and 1986 at 17 billion standard cubic metres of gas per year. This volume corresponded to 30-40 per cent of Britain’s natural gas consumption.

Since Frigg straddled the UK-Norwegian boundary, it had been resolved that the field would be developed in three phase and with Norwegian and British sections. See the unitisation agreement, economics and society.

Phase I involved development of the British side, with concrete drilling platform 1 (CDP1), treatment platform 1 (TP1), the flare platform (FP), the quarters platform (QP), a 32-inch pipeline running for 360 kilometres from TP1 to Scotland, the manifold compression platform 01 (MCP-01) midway between Frigg and the mainland, and the receiving terminal at St Fergus.

The second phase covered the development of the Norwegian share, with drilling platform 2 (DP2) and treatment compression platform 2 (TCP2) and a 32-inch pipeline running for 360 kilometres from TCP2 to Scotland. Phase III was the expansion of TCP2 with compressors to maintain gas pressure from the field.

Phase I

CDP1 was a Doris design. A characteristic feature of this solution was the honeycombed breakwater, also seen on the Ekofisk tank. This platform was built at Åndalsnes by Norwegian Contractors, and was towed from that site to Frigg in September 1965 and installed by being ballasted down on the seabed in 98 metres of water. The topside modules were then installed. The first production well on CDP1 was spudded on 10 November 1976.

Serving as a safety valve, FP burnt off gas if excess pressure arose in the production system. Built at Rouen in France, it was installed on the field in October 1975 and attached to a foundation on the seabed by a universal joint which allowed the column to move horizontally with currents and winds.

QP was the nerve centre for the whole Frigg field, with control room, helideck and telecommunication equipment. This structure was built in France, towed to the field in several sections and installed during the summer and autumn of 1975. It was ready for occupation by the summer of 1977.

Designed by Sea Tank Company in Paris, TP1 was supported by a concrete gravity base structure (GBS) and built at Ardyne Point in Scotland in 1975-76. It was towed from this site around the north of Scotland and Shetland before being installed on the seabed in 104 metres of water on 5 June 1976. It was linked by a bridge with QP and by flowlines with CDP1 and FP.

Total Oil Marine, with its head office in Aberdeen, was operator for both the Frigg UK Pipeline and the Frigg Norwegian Pipeline. These were laid from TP1 and TCP2 respectively to St Fergus between 1974 and 1977.

MCP-01 was installed on the pipeline in 94 metres of water in June 1976, roughly midway between Frigg and St Fergus. Like CDP1, it was a Doris design with a concrete GBS. However, the latter was built at Strömstad in Sweden.

The St Fergus receiving terminal was built to treat gas from Frigg before it was sent on to the British Gas Corporation’s distribution network. This facility stood ready in 1977.[REMOVE]Fotnote: St Fergus-terminalen. Knutepunkt for norsk gass, Total Journal no 1 1993