It signalled this morning it is ready to begin the process of disposing of its non-core assets.
Chief executive Aiden Heavey said: "Active portfolio management is a key part of Tullow's exploration-led strategy.
“These transactions are part of an ongoing process of carefully refocusing our business and ensuring efficient allocation of capital by monetising non-core assets and re-investing the proceeds in high potential oil exploration."
Spring holds 28 offshore licences across Norway's continental shelf in the North Norwegian and Barents Seas covering just over 18,000 square kilometres.
It has a track record of exploration success, having made six commercial discoveries from 12 wells drilled since 2008.
In 2013-14, it plans to drill up to 16 exploration wells and operate three of them.
Tullow reckons Spring's exploration portfolio contains in excess of 230 million barrels of oil equivalent of risked prospective resources while the company has existing reserves and resources of 24 million barrels.