The Tern oil field is among seven transferred to TAQA Bratani
Several Shell operated North Sea fields have been formally transferred to an Abu Dhabi company.
TAQA Bratani, which has a base at Westhill, has bought the Tern, Kestrel, Eider, Cormorant and Pelican Fields as part of a deal worth $631m.
It has also acquired a quarter share in the Sullom Voe oil terminal.
The company has pledged to invest £500m over the next three years to prolong the life of the fields and safeguard jobs.
Peter Barker-Homek, TAQA's chief executive officer, said the transfer was a milestone for the company.
He said: "These assets are undoubtedly a great addition to our existing operations and provide TAQA with scale.
"However, the value of the people we now have within our group as a result should not be underestimated.
"More than three decades of the North Sea oil and gas industry has created a concentrated workforce with world class skills and a depth of experience which we intend to draw from as we seek to increase our European asset base and workforce."
The fields will be taken over by TAQA, with services provided by Aberdeen-based Wood Group.