Houston-based Marathon Oil Corp. (NYSE: MRO) is selling its Norwegian business to Norwegian oil company Det Norske Oljeselskap for more than $2 billion cash, as part of its shift to sell North Sea operations and focus on U.S. operations.

"The sale of our Norway assets advances one of our key 2014 priorities and further demonstrates our commitment to rigorous portfolio management to simplify and concentrate our business," Marathon Chief Executive Lee M. Tillman announced Monday.

The company said in December that it would increase capital spending to lift output and shareholder returns with $2.5 billion in buybacks.

The Norwegian deal was worth $2.1 billion after adjustments, and the cash will be used to fund share buybacks and promote organic growth, the company said. Marathon Oil has sold $6.2 billion in assets since 2011.

The company also said it is no longer trying to sell its U.K. North Sea business after failing to secure an acceptable offer.

"Accordingly, we will continue to operate this business as we always have, with a focus on our company's long-held values and commitment to safe and responsible operations," Tillman said.

Det Norske Oljeselskap ASA said it expects the deal to be completed in the fourth quarter of 2014. The plan for development and operation of the Johan Sverdrup field is scheduled for submission in February 2015.