1: There was a bubble in oil prices in 2008. The evidence for that is it popped which is a pretty good clue; although so far no one has figured out what drove the bubble. Yes it was probably speculators with access to easy money, but sadly no smoking gun has been found, although one gets the impression no one looked very hard.
2: The bubble popped, like bubbles tend to do, and then the price drifted back to what appears to have been the “equilibrium” at the time of $80 to $90 a barrel if you are talking Brent. Although by that time too Brent and WTI de-coupled so there is a bit of uncertainty about which line you should be following– if either…using your genius model which was based on a history when WTI used to sell at a premium to Brent.