OSLO, March 26 (Reuters) - Norwegian oil firm Statoil (STL.OL) said on Friday it was increasing by 10 percent its acreage in the Marcellus Shale, a huge gas formation in the United States, in a deal worth $253 million.
Statoil is adding some 236 square kilometres (59,000 acres) of land to the 2,400 squares kilometres (600,000 acres) it already owns in North-West America.
Norway's largest oil firm has a 32.5 percent interest in the project, after it concluded a deal with Chesapeake Energy Corporation (CHK.N) for the formation in November 2008.
"Statoil has the right to periodically acquire its share of leasehold that Chesapeake continues to acquire in the Marcellus Shale," the firm said in a statement.
"Statoil has now exercised such acquisition rights on a series of Chesapeake Marcellus Shale acquisitions," it said.
The Marcellus Shale formation, which extends across much of Pennsylvania and parts of West Virginia, Ohio and New York, is likely to be the nation's largest shale reservoir.
Statoil's equity production from the Marcellus shale gas play is expected to increase to at least 50,000 barrels of oil equivalent per day in 2012 (around 3 bcm) and at least 200,000 boepd (around 10 bcm) after 2020. (Reporting by Gwladys Fouche; editing by James Jukwey)