* U.S. firm considering selling all or part of its UK assets
* British North Sea portfolio valued at up to $2 bln
* Exxon focusing on U.S. shale and new projects(Adds analyst comment)
By Ron Bousso
LONDON, Aug 13 (Reuters) - Exxon Mobil isconsidering a sale of its assets in the British North Sea aftermore than 50 years in the oil and gas basin as it focuses onU.S. shale production and new projects.
The world's largest publicly traded energy company has heldtalks with a number of North Sea operators in recent weeks togauge interest in some or all of its assets, which could fetchup to $2 billion, according to three industry sources withknowledge of the matter.
Exxon declined to comment.
Leaving the British North Sea would mark a major retreatfrom Europe for Irving, Texas-headquartered Exxon, which hasalready put its Norwegian offshore assets on the block.
It would follow similar moves by U.S. rivals Chevron andConocoPhillips which earlier this year sold the bulk of theirNorth Sea operations.
Most of Exxon's operations are managed through a 50-50 jointventure with Royal Dutch Shell, known as EssoExploration and Production UK, and include interests in nearly40 oil and gas fields.
Shell declined to comment.
Exxon produces around 80,000 barrels of oil and 441 millioncubic feet of gas a day in the British North Sea, according toits website.
Potential buyers could include large private equity-backedNorth Sea producers such as Chrysaor or Neptune which haveacquired portfolios from veteran producers in recent years.
Assigning a value to oil and gas assets in the North Sea iscomplicated because many fields and infrastructure are nearingthe end of their lives and require dismantling, ordecommissioning, an expensive process which can offset years ofproduction revenue.
Neivan Boroujerdi, North Sea analyst at consultancy WoodMackenzie, said an Exxon exit was expected, valuing it at around$2 billion.
“Combined with its Norwegian assets, which ExxonMobilrecently announced its intention to market, could see thesupermajor reach one-third of the way to meeting its $15 billiondivestment target," Boroujerdi said.
Exxon’s UK business “is attractive. It is highly cashgenerative, with operating costs around half of the UK average.”
The North Sea has seen a revival in production in recentyears due to new fields coming on line and improved performanceby operators following the 2014 oil price collapse.
Still, the basin's production is expected to decline overthe next decade, according to the UK Oil and Gas Authority.
Should the direct discussions with potential buyers notyield a result, Exxon will consider appointing an external bankto run a formal sale process, two of the sources added.
It was unclear if a sale of assets would require breaking upthe Esso joint venture.
Esso has been producing gas since 1968 and oil since 1976,including from the Brent field, which is eponymous with theglobal crude benchmark and is now being decommissioned.
Exxon's operational focal point in recent years has turnedto the United States, where it is rapidly ramping up oilproduction in the Permian Basin, as well as in Guyana, where itis developing huge, untapped fields.
(Additional reporting by Gary McWilliams in Houston; Editing byJason Neely and Mark Potter)
