The acquisition by Norwegian energy giant Statoil of a minority stake is a vote of confidence for regional operations, Lundin Petroleum's CEO said Thursday.

Statoil said it spent $538 million to acquire an 11.9 percent stake in Lundin Petroleum, describing it as a way to add value to its position on the Norwegian continental shelf.

Alex Schneiter, Lundin's chief executive officer, said the acquisition was a common-sense strategy that would encourage momentum in the region.

"I see this as a vote of confidence in Lundin Petroleum and a further sign of us being one of the most attractive players on the Norwegian continental shelf," he said in an emailed statement.

Lundin has struggled through the market downturn, trimming its production guidance lower last year to 32,000 barrels of oil equivalents per day as a result of less than expected output from the Brynhild filed off the coast of Norway and infrastructure delays for its Edvard Grieg rig. It left 2014 with $758.2 million in revenue, 33 percent less than the previous year. Revenues for the first half of 2015 were down nearly 40 percent year-on-year.

Biraj Borkhataria, an analyst with RBC Capital Markets, said the main attraction for Statoil was the proved plus probable reserves of 790 million barrels of oil equivalents held by Lundin. Long-term, the deal makes sense, but it may carry some short-term risk.

"We are surprised by this move," Borkhataria said in an emailed statement. "Lundin is one of the more expensive stocks in the International exploration and production universe."

Statoil echoed that rationale, saying the acquisition would increase its exposure to Edvard Grieg and the giant Johan Sverdrup field, a field that should generate $200 billion in revenues over the next 50 years. The investment in Lundin, the company said, underpins its long-term interests in the Norwegian continental shelf.

"We consider this a long term shareholding," Statoil CEO Eldar Saetre said in a statement. "The Norwegian continental shelf is the backbone of Statoil's business."

Shares in Lundin (LUPE) were up more than 10 percent while Statoil (STO) shares fell 2 percent following the announcement of the deal.