Barring major new discoveries, I don't think oil will ever drop below $30 again. Worldwide demand is growing too strongly for that. Oil will hit $60 within two years despite everyone's best efforts to produce more.
I'd agree with that except for one thing. The Chinese economic boom is largely responsible for the increased demand in oil. They really haven't hit their first recession yet but it's inevitable. When they do, the demand for oil will drop sharply and so will prices. Will prices drop below $30? I don't know.