> An export ban wouldn’t really help much: US oil production is (now) predominantly light crude, while US refinery capacity is oriented towards heavy crude from the gulf or Venezuela.

That's not too much of a problem. A refinery tooled for heavy sour crude technically can process light, heavy, sour and sweet crude - the other way around would be an issue because you'd need to construct hydrocracker and desulfurizer stages first.

The issue is a financial one. A refinery is often a multi-billion dollar asset, and having significant parts of its value sit around unused for prolonged times means write-offs which means stonk number go down, and as we all know there is nothing more important for the economy than the stonk market.

Another, but smaller, problem is that running a refinery on different crude compositions means that the volume ratio of the various oil products changes, and the refinery may find itself sitting on more, say, heavy fuel oil than it can store, sell and ship. And once the tanks are full, production has to stop.