It's an interesting perspective, and looking back at history I'm inclined to believing that. A question about those refineries for heavy crude oil: isn't that possible to adapt the oil plants to lighter oil? Or would that mean rebuilding the whole facility?

You end up with useless processors, and you are working against the market. Converting increases the demand for light and decreases the demand for heavy, which will at least directionally improve the supply cost advantage of the heavy.