ExxonMobil is negotiating to return to Venezuela and has shown interest in the large Petromonagas heavy oil project in the Orinoco Belt - where the US energy major previously had a stake - as well as in areas in the neighboring Carabobo block, according to people familiar with the matter. A reentry into Venezuela by Exxon, if finalized, would mark a staggering reversal for the company after it exited the OPEC country nearly two decades ago amid a dispute triggered by the nationalization of its oil projects by the government of former President Hugo Chavez.