“..Refineries in the US are optimized to handle a mixture of light and heavy crude....”
Generally speaking; yes.
However, the two that I mentioned were/are designed specifically to handle the heavy, nasty, dirty crap that’s considered oil out of Venezuela. I believe they’re even owned by Venezuela’s oil company.
Rosneft and PetroChina are doing just fine in Venezuela.
No one seems to have asked Maduro if he’s interested in Chevron.