* Deal would make Chrysaor biggest UK oil, gas producer
* Chrysaor backed by private equity firm EIG Global Partners
By Shadia Nasralla and Ron Bousso
LONDON, April 17 (Reuters) - Private-equity backed Chrysaor is near a deal to buy U.S. group ConocoPhillips' British North Sea oilfields, two sources close to the process said, a deal that would make it the basin's biggest producer.
Britain's ageing North Sea has undergone a major transformation in recent years as long-standing producers have sold assets to smaller players such as Chrysaor that say they can squeeze more money out of fields due to nimbler operations.
Chrysaor and Conoco have agreed on the main terms of the acquisition in recent weeks but the deal, expected to be signed in the coming days, could still fall through, the sources said.
Conoco, having entered the British North Sea over 50 years ago, produced around 77,000 barrels of oil equivalent per day (boed) there in 2018, according to its website.
With Chrysaor aiming to produce up to 130,000 boed by next year, the acquisition would catapult it to becoming the British North Sea's largest producer ahead of BP, which is aiming to grow its British North Sea output to 200,000 boed by 2020.
BMO Capital Markets and Jefferies are acting for Chrysaor in relation to the Conoco assets, the sources said.
The value of the deal and how much cash would actually change hands was still unclear.
Parties involved in the bidding process estimated the assets could be worth up to $2.8 billion, depending on which date the sides agree as the start of the deal, which could go back to as early as January 2018.
Chrysaor, backed by private equity firm EIG Global Partners, became one of the biggest North Sea player after acquiring assets from Royal Dutch Shell for $3.8 billion in 2017.
Energy and chemicals firm Ineos, privately owned by British billionaire Jim Ratcliffe, had previously abandoned exclusive talks with the U.S. company over the fields, including a 7.5 percent stake in the Clair project West of the Shetland Islands, whose other owners are BP, Shell and Chevron.
Another bidder was energy-focussed private equity group HitecVision, which has been expanding aggressively in the Norwegian North Sea, partially in partnership with Eni .
Shell has said it produced 140,000 bpd last year , Total around 180,000 boed and smaller companies such as Premier and EnQuest produce less than 100,000 boed in the British North Sea, according to company and Stifel research data.
Chevron, which is estimated to produce around 75,000 bpd in the region, is also in process of selling its British North Sea assets. Israel's Delek via its North Sea unit Ithaca Energy is front-runner for the portfolio, industry sources say.
Chrysaor, Jefferies and BMO declined to comment. A ConocoPhillips spokesman said the group was marketing its British North Sea assets excluding London and Teesside but would not comment further.
Additional reporting by Gary McWilliams in Houston; editing by David Evans