Troll gas field
Troll is a natural gas and oil field in the Norwegian sector of the North Sea, one of the biggest in the North Sea, holding 40% of Norway’s gas[1] – it also possesses significant quantities of oil, in thin zones under the gas cap, to the west of the field. The field as a whole consists of the main Troll East and Troll West structures in blocks 31/2, 31/3, 31/5 and 31/6,[2] about 65 kilometres (40 mi) west of Kollsnes, near Bergen.[3] Most of the gas lies in Troll East.[4]
| Troll field | |
|---|---|
 Troll A platform in the Troll gas field | |
  | |
| Country | Norway |
| Region | North Sea |
| Location | North Sea |
| Blocks | 31/2, 31/3, 31/5, 31/6 |
| Offshore/onshore | offshore |
| Coordinates | 60.645556°N 3.726389°E |
| Operator | Equinor |
| Partners | Equinor, Petoro, Shell, ConocoPhillips, TotalEnergies |
| Field history | |
| Discovery | 1979 |
| Start of production | 1995 |
Operators
The field is operated by Equinor, which has a 30.58% interest. The other partners are Petoro (56%), Shell plc (8.1%), ConocoPhillips (1.62%) and TotalEnergies (3.69%).[3]
Platforms
Gas and oil from the field is extracted via three platforms – Troll A, B and C.[3]
The Troll A platform, based on the Condeep technology, is the tallest structure ever to be moved. Total weight is 656,000 tons and the total height is 472 metres (1,549 ft). The legs extend 303 metres (994 ft) below sea level.[5] This platform came into production in 1996 after being towed out from Rogaland in May 1995 [6]
The Troll B Platform is a semi-submersible designed by Doris and fabricated from concrete; thought to be the only concrete semisubmersible. This platform came into production in 1995.
The Troll C Platform is a conventional steel hull semi-submersible designed by GVA Consultants. This platform came into production in 1999.
Area
Extending across four North Sea blocks, the whole field covers just over 700 square kilometres, corresponding to about 100 000 football pitches.[7]
Geology
The reservoir is located in three eastward-tilted fault blocks 1500 m subsea and consists of cyclic shallow-marine sandstones from the Fensfjord, middle Heather, Sognefjord and upper Heather formations in the Jurassic Viking Group, and are overlain by Upper Jurassic to Paleocene clays.[2] Located in the eastern margin of the Viking Graben, water depths range from 300–355 m.[2]
References
- Equinor webpage Troll area
- Bolle, L., Troll Field, 1992, in Giant Oil and Gas Fields of the Decade, 1978-1988, AAPG Memoir 54, Halbouty, M.T., editor, Tulsa: American Association of Petroleum Geologists, ISBN 0891813330, pp. 447-458
- "Statoil". Archived from the original on 2014-09-25. Retrieved 2013-11-27.
- Offshore Technology Website Troll Archived 2009-09-30 at the Wayback Machine
- Troll A Platform at Structurae
- Eide, Ole Jone. "Troll A – giant move from fjord to field". Equinor 50 years. Norsk Oljemuseum. Retrieved 21 November 2022.
- Lindberg, Björn. "How large is a troll?". INDUSTRIMINNE.NO. Norwegian Petroleum Museum.
