The largest oil and gas fields on the Norwegian continental shelf

How the size of a field is measured

A field can be large in two ways: it can produce a lot now, or it can have a lot left. Oseberg is still among the biggest producers but has recovered 90 % of what it is expected to yield. Johan Castberg, on stream since 2025, has recovered 7 %.

• Annual production is what a field delivered in a calendar year. The figures here are marketable production from the Norwegian Offshore Directorate (Sodir), meaning oil and gas delivered for sale, summed from the monthly figures for 2025, the last full year in the data.
• Remaining reserves are what is left of the volumes the licensees have decided to produce, not everything in the subsurface. The difference is explained in the guide to the Norwegian shelf.
• Oil equivalents (o.e.) let oil, gas, NGL and condensate be added together. Sodir counts 1,000 Sm³ of gas as 1 Sm³ o.e., so 41 billion Sm³ of gas becomes 41 million Sm³ o.e. A standard cubic metre (Sm³) is a volume at fixed pressure and temperature, and 1 Sm³ of oil is about 6.29 barrels.
• NGL (natural gas liquids) are heavier components such as ethane, propane and butane, separated from the gas. Condensate is light hydrocarbons that are gas in the reservoir but turn liquid on the way up.

Which field is the “largest” therefore depends on the yardstick. In oil equivalents Troll comes first, because its gas is counted. On oil alone, Johan Sverdrup leads by a wide margin.

The 20 fields that produced the most in 2025

According to Sodir's monthly figures, the Norwegian shelf produced 240.5 million Sm³ o.e. in 2025 from 96 fields and discoveries. Gas made up 50.7 % of that, oil 44.4 % and NGL and condensate together 4.9 %.

Output is heavily concentrated. Troll and Johan Sverdrup alone accounted for 35.7 % of everything produced, the ten largest fields for 60.8 % and the 20 in the table for 76.2 %. The other 76 fields and discoveries shared the remainder, just under a quarter.

The figures were retrieved from Sodir on 7 October 2026. norskpetroleum.no gives 239.2 million Sm³ o.e. for 2025 because it converts the gas to a fixed calorific value of 40 megajoules per Sm³; the monthly field figures behind the table measure gas by volume, 121.8 billion Sm³. The field overview is sorted by the last twelve months, so its order can differ slightly.

The largest oil fields

Johan Sverdrup is Norway's largest oil field. In 2025 it produced 40.07 million Sm³ of oil, 37.5 % of all the oil from the shelf, or roughly 690,000 barrels a day. In second place came Johan Castberg in the Barents Sea with 6.31 million Sm³, even though it only started up at the end of March.

The list mixes new fields with old ones. Johan Sverdrup started in 2019, Breidablikk in 2023 and Johan Castberg in 2025, while Ekofisk has been producing since 1971 and Eldfisk since 1979. In total the shelf produced 106.8 million Sm³ of oil in 2025, about 1.84 million barrels a day.

The table covers oil only; condensate and NGL count in the first table but not here. Barrels per day is a full-year average, so it understates Johan Castberg's daily rate after start-up.

The largest gas fields

Troll is Norway's largest gas field by a long way. It lies in the North Sea and is operated by Equinor. In 2025 Troll delivered 41.00 billion Sm³ of gas, 33.6 % of all the gas from the Norwegian shelf. Ormen Lange and Oseberg followed with about 7.7 billion Sm³ each. Equinor operates eight of the ten largest gas fields; the exceptions are Ormen Lange, operated by Shell, and Skarv, operated by Aker BP.

The gas travels by pipeline, often through a processing plant on land: Troll gas is processed at Kollsnes, and the gas from Ormen Lange and Aasta Hansteen goes to Nyhamna. Snøhvit is the odd one out, as its gas is liquefied at Melkøya near Hammerfest and shipped as LNG. The pipelines and the buyers are covered in the guide to gas from the Norwegian shelf to Europe.

Troll, Johan Sverdrup and the other large fields

Troll in the North Sea was discovered in 1979, its development plan was approved in 1986 and production began in 1995. The field has two main structures, Troll Øst and Troll Vest, and about two thirds of the gas lies in Troll Øst. The gas is produced from Troll A, a fixed platform on a concrete substructure that is powered from shore, and processed at Kollsnes. The oil in Troll Vest comes from subsea templates tied back to the floating Troll B and Troll C. It is now a small part of the field, 1.46 million Sm³ in 2025, and drilling of oil wells has ended.

Johan Sverdrup lies on the Utsira High in the central North Sea. It was discovered in 2010; the first phase came on stream in 2019 and the second in 2022. The platforms at the field centre are linked by bridges, and the field is powered from shore. Output was 42.22 million Sm³ o.e. in 2025, slightly below the 43.74 million of 2024, and Sodir estimates that 52 % of the reserves have been produced. Equinor is the operator with 42.63 %; Aker BP holds 31.57 %, Petoro 17.36 % and TotalEnergies 8.44 %.

Oseberg in the northern North Sea was discovered in 1979 and has produced since 1988. It was developed in several phases, and its oil is piped through the Oseberg Transport System to the Sture terminal. The aim now is to take out more and more gas while keeping oil output up, and the first dedicated gas wells were drilled in 2023. In 2025, 77 % of production was gas, and less than 10 % of the reserves remain.

Ormen Lange in the southern Norwegian Sea is, by 2025 output, the largest field not run by Equinor; the operator is Shell. It was discovered in 1997 and has produced since 2007. There is no platform: the wells sit on the seabed and the well stream flows through two pipelines to the processing plant at Nyhamna, from where the gas is exported through Langeled to Easington. Subsea gas compression came into operation in 2025 to extend the field's life.

Gullfaks Sør, just south of Gullfaks, has no platform of its own either. Its deposits are developed with subsea templates tied back to Gullfaks A and Gullfaks C, and production started in 1998. Output rose from 6.64 million Sm³ o.e. in 2024 to 7.84 million in 2025, 73 % of it gas.

Åsgard in the Norwegian Sea was discovered in 1981 and has produced since 1999. Its subsea wells are tied back to the production ship Åsgard A, the semi-submersible gas platform Åsgard B and the storage ship Åsgard C, and the gas goes through Åsgard Transport to Kårstø. Sodir classifies Åsgard as a gas and condensate field, yet it appears in the oil table, because the condensate from Åsgard is sold as oil.

Aasta Hansteen in the northern Norwegian Sea was discovered in 1997 and came on stream in 2018. Its platform is a spar, a floating structure with a tall cylindrical hull, and the gas goes through Polarled to Nyhamna. The field came off plateau in 2024, meaning it no longer produces as much as its facilities can handle, and output fell from 8.47 million Sm³ o.e. in 2024 to 7.19 million in 2025.

Johan Castberg in the Barents Sea, about 100 kilometres north-west of Snøhvit, combines the Skrugard, Havis and Drivis discoveries, made between 2011 and 2013. It is developed with a production ship (FPSO) and subsea wells, and the oil is collected by shuttle tankers. Production began at the end of March 2025, so the field ranked ninth for the year after about nine months of output. Over the last twelve months in the data, August 2025 to July 2026, it ranked third with 10.42 million Sm³ o.e., behind Troll and Johan Sverdrup. Equinor is the operator with 46.30 %; Vår Energi holds 30 % and Petoro 23.70 %.

The ownership shares are from Sodir's licensee table, updated on 20 February 2026 and retrieved on 7 October 2026.

How much is left

Sodir's estimates as of 31 December 2025 put the remaining reserves in the fields on the shelf at 2,165 million Sm³ o.e., the same total as in the resource accounts on norskpetroleum.no. Troll alone holds 26.6 % of that, Johan Sverdrup 9.3 % and Snøhvit 7.6 %.

This is not the production ranking. Snøhvit produced 4.83 million Sm³ o.e. in 2025 but has 165 million left, more than any field apart from Troll and Johan Sverdrup. Munin and Hugin are not yet producing: both are approved for development, with Aker BP as operator. Oseberg and Ormen Lange, by contrast, have recovered more than 80 % of their reserves. The estimates change from year to year as companies learn more about the reservoirs and new projects are approved.

Where the fields are: North Sea, Norwegian Sea and Barents Sea

The Norwegian shelf is divided into three sea areas, and most of the output comes from the southernmost.

• The North Sea accounted for 73.0 % of production in 2025, from 68 fields and discoveries. The largest are Troll, Johan Sverdrup, Oseberg, Gullfaks Sør, Visund, Snorre, Breidablikk and Ekofisk. Ekofisk, on stream since 1971, is the oldest field still producing.
• The Norwegian Sea accounted for 21.8 % from 25 fields, led by Ormen Lange, Skarv, Åsgard, Aasta Hansteen, Tyrihans and Heidrun.
• The Barents Sea accounted for 5.2 % from three fields: Johan Castberg, Snøhvit and Goliat.

The fields can be shown on the globe on the analysis page, and monthly output for the whole shelf is under Production on the Norwegian shelf.

Who runs the fields

The operator runs a field in practice, with drilling, development and operations, on behalf of all the licensees, that is the owners. It usually holds a share itself, but not necessarily the largest.

Equinor operates 15 of the 20 largest fields. Of the 96 fields and discoveries that produced in 2025, Equinor ran 54, and they accounted for 76.6 % of output. Next come Aker BP with 17 fields and 8.6 %, led by Skarv, Alvheim and Valhall; ConocoPhillips with 5 fields and 4.0 %, among them Ekofisk and Eldfisk; Shell with Ormen Lange (3.4 %); Vår Energi with 6 fields and 3.2 %, led by Balder; and Harbour Energy with 4 fields and 2.7 %.

The owners are a different list. The state holds large stakes directly through Petoro, which manages the State's Direct Financial Interest (SDFI) but operates no field. Petoro owns 55.93 % of Troll and 36.49 % of Ormen Lange. Each field page lists all the licensees, and the company pages calculate how much each listed company produces according to its stakes.

All the fields, companies and sources

• Fields on the Norwegian shelf covers all 141 fields in Sodir's field list, with production per year since 2000, reserves, licensees and facilities.
• The pages for Equinor, Aker BP, Vår Energi, OKEA and DNO show each company's stakes; all the companies are in the overview.
• The guide to offshore installations explains the platform types mentioned here: concrete platforms, production ships, spars and subsea systems.
• The figures come from Sodir's FactPages, and norskpetroleum.no has a page for each field.

Sources

• Field production by month – Norwegian Offshore Directorate, FactPages – marketable production per field in 2025 and over the last twelve months; retrieved 7 Oct 2026
• Fields, reserves and licensees – Norwegian Offshore Directorate, FactPages – sea area, operator and status (retrieved 28 Sep 2026), reserves as of 31 Dec 2025, start-up years and ownership shares (retrieved 7 Oct 2026)
• Production forecasts – norskpetroleum.no – the 2025 total with gas counted as 40 MJ gas; read 24 Oct 2026
• Resource accounts for the Norwegian shelf as per 31.12.2025 – norskpetroleum.no – total remaining reserves; read 24 Oct 2026
• Troll – norskpetroleum.no – structures, facilities, Kollsnes, oil wells
• Johan Sverdrup – norskpetroleum.no – location, phases, field centre, power from shore
• Oseberg – norskpetroleum.no – development, oil transport, gas wells
• Ormen Lange – norskpetroleum.no – subsea development, Nyhamna, Langeled, subsea compression
• Gullfaks Sør – norskpetroleum.no – subsea templates tied back to Gullfaks A and C
• Åsgard – norskpetroleum.no – facilities, Åsgard Transport, condensate sold as oil
• Aasta Hansteen – norskpetroleum.no – spar platform, Polarled, off plateau in 2024
• Johan Castberg – norskpetroleum.no – the discoveries, location, production ship
• Snøhvit – norskpetroleum.no – the LNG plant at Melkøya
• Norwegian Licence for Open Government Data (NLOD)

The guides are written by OESA students to explain concepts and how things fit together. They are not investment advice. Figures that are not definitions carry a source and a date; if you find an error, let us know at philipstave@oesa-global.com.