Norway’s Equinor said it agreed to buy Chevron’s 40% stake in the Rosebank oilfield west of Scotland’s Shetland Islands for an undisclosed sum.

Rosebank is one of the largest undeveloped fields on the UK Continental Shelf (UKCS).

The project is currently estimated to cost about $6 billion, according to WoodMackenzie.

The Rosebank field was discovered in 2004 and lies about 130 km northwest of the Shetland Islands in water depths of approximately 1,110m.

The other partners in the field are Suncor Energy (40%) and Siccar Point Energy (20%).

“With Rosebank, a standalone development in the underexplored West of Shetland region, we strengthen our upstream portfolio, which also includes Mariner, one of the largest investments on the UKCS in over a decade,” said Hedda Felin, Equinor’s senior vice president for UK & Ireland offshore.

“As we have done with other projects in our portfolio, such as Johan Castberg and Bay du Nord, we intend to leverage our experience and competence to create further value in Rosebank, in alignment with the UK Government’s priority of maximising the economic recovery of the UKCS.”