Billions of barrels of Venezuela’s oil claimed by major state-owned Chinese and Russian companies under current deals are now in doubt following the U.S. capture of Nicolas Maduro, according to investment bank Morgan Stanley. Oil giant and top Asian refiner China Petroleum & Chemical Corporation, or Sinopec, is entitled to as many as 2.8 billion of barrels under current agreements with Venezuela’s state oil firm PDVSA, per a note by Morgan Stanley Research cited by Bloomberg. That’s the single biggest clam by a…