Swedish oil firm Lundin Petroleum said today that drilling had commenced on the Alta discovery in the southern Barents Sea.
Alta was discovered in 2014 and three successful appraisal wells have been completed to date.
The nearby Gohta discovery could be developed alongside Alta, Lundin said. They could contain 115-390million barrels of oil.
The Leiv Eiriksson semi-submersible drilling rig is working on the well, which will be used to test production rates.
The well will be tested for about two months.
At the end of the test, the produced oil and water will be delivered to the Mongstad oil terminal on the west coast of Norway.
The results will help guide plans for appraisal drilling and field development activities.
Drilling and testing is expected to take 140 days.
Operator Lundin has a 40% stake in the licence.
The partners are Dea and Idemitsu with 30% each.