Following the unexpected arrest of Venezuelan President Maduro in the United States, U.S. oil stocks extended their gains from Monday, as investors closely monitor whether and how U.S. companies will be granted access to Venezuela’s oil reserves.Chevron, currently the only U.S. oil company operating in Venezuela, rose another 0.7% in premarket trading after surging on Monday. According to NBC, President Donald Trump said on Monday that the U.S. might subsidize oil companies’ investments in the country.Other oil giants seen as potential entrants into the country also rose in premarket trading, with ExxonMobil up 0.5% and ConocoPhillips jumping 0.8%. Oilfield services giants Schlumberger and Halliburton rose 2% and 0.2%, respectively.