New Delhi, Sept. 1 -- One thing is clear from U.S. President Donald Trump's oracular Aug. 28 announcement of "the biggest oil deal in world history" with Venezuela and Venezuelan counterpart Delcy Rodriguez's sketchy clarifications: The two leaders are doubling down on each other.

That won't necessarily facilitate the $100 billion of U.S. investment in Venezuelan hydrocarbons that Trump promises.

Oil drilling generally involves daunting capital expenditures that pay back over years if not decades. That's particularly true in Venezuela, whose "super heavy" crude reserves require a very expensive "upgrading" process before refining into fuels and petrochemicals, says Clayton Seigle, a senior associate at the Center for Strategic and Inter...