If Maduro offered you a boat load of oil in exchange for you buying some over priced Petros, it might make sense.  For instance, lets say you value the oil at $100K, and Maruro values it at $60K.  You buy $80k of BTC, then exchange them all for petros through Maduro and he gives you a free boat load of oil.  Masduro gets 80K of BTC, you get worthless petros and oil you value at $100k.  You saved $20K and Maduro made $20K over his expected value of Oil.  If the petros become worth anything someday, you made even more.

Why offer Petros at all?  Can't he just sell the oil for $80K BTC?  Maduro benefits by showing that you bought 80K of petros, not 100K of oil.  The oil purchase doesn't have to be logged at all.

Why wouldn't Maduro just charge $100K USD for the oil and make more?  Because of the embargo.  Somehow he has to exchange the 100K USD back to gold or BTC or whatever he holds his assets in.  I'm sure he holds lots of USD, but he's already having trouble spending that.