The API blogger calls recently discussed that. It is FAR cheaper and years faster to expand existing refineries than to build new refineries. They were saying they added something like the equivalent of 3 new refineries over past ten years by expansion. [check my numbers] Still, I think the point that there will be less oil in the future must play in that. Somewhere I saw an article that oil tankers were not being built for that reason.

cfm in Gray, ME

10 new refineries in 10 years. Total capacity increase of 2 million bpd.