Exxon Mobil and Shell are in advanced talks with several potential firms to divest their stakes in oil and gas joint venture (JV) Aera Energy, reported Reuters, citing three people with knowledge of the matter.

The sale forms part of the two firms’ efforts to focus on larger-scale oil fields and liquefied natural gas (LNG) projects by exiting older operations to reduce greenhouse gas emissions.

California-based oil producer Aera Energy has a production capacity of 125,000 barrels of oil and 32 million cubic feet of natural gas per day.

Last year, Reuters reported that Shell was considering the sale of its stake in Aera Energy, which has assets primarily in the San Joaquin Valley, to shift its focus towards clean energy and reduce carbon emissions.

Exxon has now joined Shell in the stake sale effort.

With assistance from financial adviser JPMorgan Chase, Exxon and Shell have been in talks with several potential buyers, including solo and consortia, according to sources.

Exxon and Shell have been offloading older properties to reduce debt and invest in new areas.

A potential deal could allow Exxon to reach its $15bn assets sale target, which was set four years ago.

The company intends to shift its focus to Guyana and Brazil offshore and LNG projects.

Last month, Reuters reported that Shell appointed investment bank Jefferies to run the sale of its 30% stake in the Cambo oil prospect in the British North Sea.

The Cambo oil field is expected to yield up to 170 million barrels of oil equivalent over a period of 25 years, and 53.5 billion cubic feet of gas.