Hey dude, I never said or implied it was a terrorist attack! I think it might be a possibility, but the simplest solution is usually the best. The Occam Razor principle states that one should not make more assumptions than the minimum needed. Base on all available data this appears to be an accident.
It seems quite unlikely that we're looking at terrorism here. Terrorists want large numbers of casualties, much more than structural damage, so blowing up an oil refinery is not really their style.
There are reports that the fire broke out on a barge that was refueling at the refinery. I'm betting that this was an accident, just like the fire in Rhode Island.