Crude prices are low. Companies are being cautious. But huge reserves — particularly of the heavy, viscous oil Venezuela has in abundance — remain appealing.

Shares in Chevron, Exxon and other energy companies climbed, while oil prices jumped, on Monday after Maduro's ouster.

Exxon’s CEO says the South American country is currently “uninvestable” and plans to send a technical team to assess the situation.

Trump said on Saturday that the oil embargo on Venezuelan exports remained in full effect. If the U.S. government loosens the embargo and allows more Venezuelan crude exports to the U.S. Gulf, there are refiners there that previously processed the country's oil.

US energy secretary Chris Wright said on Thursday that Big Oil’s arrival in Venezuela could push up its output as much as 50 per cent to 1.2mn barrels a day within 12 months. “I think you’ll see more downward pressure on the price of gasoline,” he told Fox News.

President Donald Trump’s push to unlock Venezuelan crude is strengthening the political case for a proposed pipeline that would allow Canada to ship more oil to China and other Asian markets. Refineries in the American Midwest are configured to process Canada’s heavy crude.

Venezuela's state-run oil company PDVSA said on Wednesday it is progressing in negotiations with the United States for oil sales, as a board member for the company told Reuters the U.S. will need to buy cargoes at international prices.

Oil stocks were soaring early Monday even as crude prices were largely unmoved following the surprise U.S. operation to capture Venezuelan President Nicolás Maduro.