We are expanding more than one, and have been for a while. Refineries have been expanding within and around their existing locations, and efficiency is also up. As Fig. 5 shows, refining "capacity," however defined, has been trending upward nicely over the last 15 years.
Longer than that.
We hear pundits harping about no new refineries all the time, usually right before they start calling for some goofy new federal energy "solution". We only seem to hear about the rest of the refinery story on the Freerepublic.
No new refineries have been built because they haven't been needed. The oil price shock of the late '70's made a big change in the worlds oil usage. So much so that OPEC doesn't even want to think about pulling a stunt like that again.
A quarter century later we're barely back up to where we were as far as using what was there. We've got a long way to go before new refineries are needed, if ever.