Oil producer Chevron is in talks with the U.S. government to expand a key license to operate in Venezuela so it can increase crude exports to its own refineries and sell to other buyers, four sources close to the negotiations said on Wednesday. The talks come as Washington and Caracas progress in talks to supply up to Rs 50 million barrels of Venezuelan oil to the United States and President Donald Trump presses American oil companies to invest in the South American country's energy sector.