The Troll field lies in the northern part of the North Sea, around 65 kilometres west of Kollsnes, near Bergen.

The field comprises the main Troll East and Troll West structures in blocks 31/2, 31/3, 31/5 and 31/6.

Containing about 40 per cent of total gas reserves on the Norwegian continental shelf (NCS), it represents the very cornerstone of Norway’s offshore gas production.

Troll is also one of the largest oil fields on the Norwegian continental shelf. In 2002 the oil production was more than 400,000 barrels per day.

Statoil operates the Troll A, B and C platforms and the landfall pipelines, while Gassco is operator for the gas processing plant at Kollsnes on behalf of Gassled. Statoil is technical service provider for Kollsnes operations.

The enormous gas reservoirs lying 1,400 metres below sea level are expected to produce for at least another 70 years.

Proven in 1979

Norske Shell was chosen as operator when block 31/2 was awarded in April 1979. A large gas find with an underlying oil zone was proven later that year. The block was declared commercial in 1983.

The neighbouring blocks were awarded to Statoil, Norsk Hydro and Saga Petroleum in 1983.

Block 31/2 contains 32 per cent of the Troll field’s reserves, while the remaining 68% lies in the three other blocks.

The licence terms for block 31/2 specified that Statoil could take over as operator for this acreage eight to 10 years after a discovery had been declared commercial.

In 1985, the two licences were unitised so that Troll could be developed as a single field.

Statoil took over as production operator for Troll Gas on 19 June 1996, while Hydro started production from Troll Oil in the fall of 1995.