By Dominic Chopping

Norwegian oil-and-gas major Equinor ASA said Friday that it has agreed to sell a 40.8125% stake in the Bressay oil field development on the U.K. continental shelf and transfer operatorship to EnQuest PLC.

The company, which is 67%-owned by the Norwegian state, said the initial consideration is 2.2 million pounds ($2.9 million), payable as a carry against 50% of Equinor's net share of costs, with a contingent consideration of $15 million following authority approval of a field development plan.

"This transaction supports Equinor's strategy to continually optimise our portfolio," said Arne Gürtner, Equinor's senior vice president for U.K. & Ireland offshore.

The Bressay oil field was discovered east of Shetland in 1976 and Equinor became operator in 2007. The concept selection for the field development was deferred in 2016 due to challenging market conditions and the need to simplify the development concept.

The transaction is subject to customary conditions, including partner and authority approval, with an estimated completion date in 4Q 2020.

Following completion, EnQuest will have an 40.8125% interest and operatorship, Equinor will have 40.8125%, with Chrysaor retaining a 18.375% interest.

Write to Dominic Chopping at dominic.chopping@wsj.com