NEW YORK (Reuters) -U.S. oil and gas producer ConocoPhillips ( COP ) is in advanced talks to sell assets in Oklahoma to privately owned Stone Ridge Energy for around $1.3 billion, three people familiar with the matter told Reuters on Tuesday.

Oklahoma City-based Flywheel Energy, a private oil and gas company backed by Stone Ridge Energy, will operate the assets on its backer's behalf, one of the sources said.

The sources cautioned that no deal is guaranteed and talks could still end without an agreement. They also spoke on condition of anonymity to discuss private deliberations.

ConocoPhillips ( COP ) declined to comment. Stone Ridge Energy, the energy-focused arm of New York-based Stone Ridge Asset Management, did not immediately respond to a request for comment.

Flywheel, which also counts commodities trader Gunvor among its investors, did not immediately respond to requests for comment.

Reuters reported in April that ConocoPhillips ( COP ) had hired investment bank Moelis & Co to manage an auction of the assets, which are comprised of operations in the Anadarko basin inherited by the energy producer as part of its $22.5 billion takeover of Marathon Oil last year.

As part of the deal, Stone Ridge Energy will acquire 300,000 net acres (121,406 hectares) in the Anadarko shale formation, which produce about 39,000 barrels of oil equivalent per day, of which about half is natural gas.

If completed, the asset sale would help ConocoPhillips ( COP ) surpass a target to raise $2 billion from divestments. Conoco set that target after it took on about $5.4 billion of Marathon's debt as part of that acquisition.