President Donald Trump's call for U.S. oil companies to rebuild Venezuela's energy sector after the overthrow of President Nicolas Maduro is easier said than done. Chevron holds the advantage as the only major U.S. oil company currently operating in Venezuela, according to Wall Street analysts. ExxonMobil and ConocoPhillips left the country after former President Hugo Chavez nationalized the industry and seized their assets in 2007. Venezuela has the largest proven crude oil reserves in the world, at 303 bi ...