Last checked at 
* Chrysaor hires Jefferies, BMO to advise
* Chevron assets include central North Sea, Clair stake
* Entire deal value expected at around $2.5 billion
* Bids due in before Christmas -sources
By Ron Bousso and Shadia Nasralla
LONDON, Dec 13 (Reuters) - Private equity-backed oil firmChrysaor has hired advisers ahead of talks to buy Chevron'sBritish North Sea oil and gas fields for over $2.5billion, industry and banking sources said.
Chrysaor has signed up investment banks Jefferies and BMOfor the discussions as a deadline for bids approaches beforeChristmas, the four sources said.
Chevron said earlier this year it was selling its assets inthe central North Sea, which are expected to fetch around $1.5billion.
Chrysaor and Chevron are also discussing the sale of part orall of the U.S. group's 19.4 percent stake in the BP-operatedClair field, the largest oil field in the British NorthSea, which was not originally up for grabs, the sources said.
The Clair stake could easily fetch $1 billion, they said.
A Chevron spokeswoman said the company does not comment onindustry speculation or commercial matters.
When asked about interest in its Clair stake, she said:"While we continue to evaluate our portfolio we are progressingthe Clair projects."
A spokesman for Chrysaor declined to comment. Jefferiesdeclined to comment. A BMO spokesman was not immediatelyreachable.
Chevron's net daily production in the North Sea in 2017averaged 50,000 barrels of oil and 155 million cubic feet ofnatural gas, according to its website.
The California-based company kicked off in July the sale ofits central North Sea oil and gas fields Alba, Alder, Captain,Elgin/Franklin, Erskine and Jade as well as the Britanniaplatform and its satellites.
On Tuesday, Chevron said that Britain's Oil and GasAuthority approved its development plans for the Captain field.
In October, Chevron sold its 40 percent stake in theRosebank development to Norway's Equinor.
Selling the central North Sea assets as well as the Clairstake would effectively mark Chevron's full exit from the ageingUK North Sea basin after over 50 years.
Chevron has in recent years focused its efforts on rapidlygrowing its shale production in the Permian basin in Texas aswell as the giant Tengiz field in Kazakhstan.
Chrysaor, backed by Harbour Energy, an investment vehicle ofEIG Global Energy Partners, became one of the largest North Seaproducers after buying $3 billion of oil and gas fields fromRoyal Dutch Shell in 2017.
With its current portfolio, Chrysaor expects dailyproduction averaging 120,000-130,000 barrels of oil equivalentuntil 2020.
(Reporting By Ron Bousso and Shadia Nasralla. Editing by JaneMerriman)
