Equinor and its partners are moving forward with plans for a fourth development phase at the giant Johan Sverdrup field after recent appraisal drilling confirmed additional recoverable resources in the North Sea.

The company said discoveries at the Tonjer West, Tonjer East, and Geitungen prospects will form the basis of Johan Sverdrup Phase 4, a proposed subsea development tied back to the field's existing infrastructure. Preliminary estimates place the combined resource potential at between 20 million and 30 million barrels of oil equivalent.

The project is being matured toward a final investment decision, with production startup targeted for 2029. By utilizing existing Johan Sverdrup facilities, the partners aim to bring the resources online quickly while keeping development costs and emissions relatively low.

"These are important and profitable volumes for Johan Sverdrup," said Kjetil Hove, Equinor's executive vice president for Development and Production Norway. He added that the discoveries would help sustain production and value creation from one of Norway's most important oil assets.

Located on the Norwegian Continental Shelf, Johan Sverdrup has been the country's largest producing oil field since coming on stream and remains a cornerstone of Norwegian crude output. The new discoveries are expected to help offset natural production declines and extend the productive life of the field.

The development also aligns with Equinor's broader strategy of accelerating subsea projects and maximizing recovery from existing infrastructure. The company has increasingly focused on tieback developments, which can often be sanctioned and executed faster than standalone offshore projects while requiring lower capital investment.

The announcement follows a recent redetermination of ownership interests in the Johan Sverdrup Unit, which slightly increased Aker BP's stake to 31.7163% from 31.5733% after an updated assessment of reserves and production data. The adjustment highlighted the continued importance of resource optimization at the field as partners seek to unlock additional value from one of Europe's most prolific offshore assets.

Johan Sverdrup is also a significant contributor to European energy supplies. As Europe continues to prioritize energy security amid shifting global energy markets, maintaining production from large, low-cost North Sea fields remains strategically important for regional oil supply.

The Johan Sverdrup partnership consists of Equinor (42.62%), Aker BP (31.57%), Petoro (17.36%), and TotalEnergies (8.44%).