Equinor has announced a new oil discovery at the Polynya Tubåen prospect in the Barents Sea, with estimated recoverable reserves of between 14 and 24 million barrels of oil equivalent (mboe).
The company will connect this discovery to the existing Johan Castberg field infrastructure. The COSL Prospector rig conducted the drilling operation at the 7220/7-5 wildcat well.
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Located in production licence 532, the well was drilled roughly 16km south-west of Johan Castberg discovery well 7220/8-1, around 210km north-west of Hammerfest.
Well 7220/7-5 intersected hydrocarbons in the Tubåen Formation, including a 26m gas column overlying a 26m oil column. The reservoir section comprises 39m of reservoir-quality rock, described as good to very good, within a total Tubåen Formation thickness of 125m.
The gas-oil contact was identified at 972m below sea level and the oil-water contact at 998m below sea level.
The Polynya Tubåen discovery follows the identification of oil in the Drivis Tubåen structure in the same area in June 2025, with estimated recoverable volumes of 13–20 million barrels (mbbl).
Equinor plans to continue its efforts to expand reserves, with a view to increasing Johan Castberg’s resource base by a further 200–500mbbl beyond its original estimate of 500–700mbbl.
Development activities are also under way following last week’s commencement of well frame construction for Isflak, which will be the first additional discovery linked to Johan Castberg.
Aker Solutions is responsible for building facilities for two more wells, which will connect to current subsea installations.
The Johan Castberg field is situated 220km north-west of Hammerfest and around 100km from the Snøhvit field in water depths of around 370m.
The field includes three discoveries, Skrugard, Havis and Drivis, made between 2011 and 2013. Authorities approved the development plan in 2018, leading to a project comprising a production, storage and offloading vessel (FPSO) supported by additional subsea templates with 18 horizontal production wells and 12 injection wells.
Production at Johan Castberg began on 31 March 2025.
Equinor exploration and production north area director Grete Birgitte Haaland said: “With Johan Castberg, we opened a new oil province in the Barents Sea one year ago. It is encouraging that we are now making new discoveries in the area.
“We plan to drill one to two exploration wells annually in this region going forward to increase the resource base and maintain plateau production for a longer period.”
The reservoirs contain oil with gas caps located within three separate sandstone formations, the Tubåen, Nordmela, and Stø, which date from the Late Triassic to Middle Jurassic periods and range from depths of 1,250–1,900m.
Equinor operates Johan Castberg with a 46.3% stake, while Vår Energi holds 30% and Petoro owns 23.7%. The first discovery at Johan Castberg occurred in 2011.
Earlier this month, Equinor made two new commercial hydrocarbon discoveries in the Norwegian North Sea, with oil found near the Troll area and gas and condensate discovered in the Sleipner area.
