Cairn Energy has bought a 50% stake in the Agar-Plantain oil fields in the British North Sea from Azinor Catalyst, the companies said June 14.

The investment by Cairn is another sign that North Sea assets are becoming attractive again to oil producers, which sold assets in the past few years, often to private equity investors, and cut costs after oil prices collapsed.

Azinor, which is backed by private equity firm Seacrest Capital and owns a portfolio of North Sea assets, discovered the Agar-Plantain fields in 2014 and said on June 14 that it expected to start drilling in the third quarter, pending regulatory approval.

Agar and Plantain have “estimated combined mid-case resources of 60 million barrels oil equivalent, with an upside case of 98 million barrels oil equivalent,” Azinor said.

The companies did not say how much Cairn Energy paid for its stake.

Renewed interest in North Sea assets was highlighted last month when Royal Dutch Shell, BP and Norway’s Equinor as well as smaller independent oil producers including Siccar Point, Chrysaor and Premier Oil awarded 229 blocks in the British North Sea.