Terms of the deal announced late Friday were not disclosed.
State-run Petroleos de Venezuela SA, or PDVSA, said it will now team up with Chevron to exploit the reserves in that area of Venezuela's Deltana Platform.
PDVSA will control 61 percent of the joint venture, and Chevron 39 percent. Some 7 trillion cubic feet of natural gas reserves have been discovered, and the project is expected to produce some 750 million cubic feet per day.
ConocoPhillips spokesman Charlie Rowton at headquarters in Houston confirmed the sale but declined to discuss the price or other terms.
He said the sale is unrelated to separate World Bank arbitration over the nationalization of ConocoPhillips' assets in heavy oil projects.
President Hugo Chavez's government nationalized four major oil projects in 2007, including ConocoPhillips' operations in the nation's heavy-oil-producing Orinoco Oil Belt, after the two parties failed to agree on terms for a minority stake.
But ConocoPhillips continued to explore for offshore natural gas deposits and had worked with Chevron since 2003 in the Deltana Platform.
Chevron spokesman Scott Walker said the San Ramon, California-based company is pleased with the deal.
"We look forward to working with PDVSA on developing this project," Walker said in an e-mailed statement.
Chavez's government said last week that it may sue ConocoPhillips for exercising an option to purchase PDVSA's 50 percent stake in a joint refinery in Sweeny, Texas.
ConocoPhillips says PDVSA has failed deliver heavy crude as required under contract to the refinery since the beginning of the year, while PDVSA says it stopped shipping 166,000 barrels of oil a day to comply with OPEC production cuts.
Rowton declined to comment Friday on a possible lawsuit.