Musings: Why is the price of oil so high?

I've been reflecting back to a conversation that I once had with a fellow co worker, a geologist who once worked for Marathon Oil. The conversation was about the price of oil, at the time, he then explained to me that price of oil was not only drive by the demand for fuel for vehicles. Oil is used is so many products plastics, paints, etc. and the price of oil is But it was something that he said that caught me by surprise. He state that Marathon calculated that the worlds oil reserves would be exhausted by the year 2015 or possibly 2020. I asked him to clarify if he meant "oil reserves on hand already extracted from ground?" His reply shocked me he stated no he meant "the entire reserve of oil in and out of the ground." With that rattling around my mind, as I watch the price of oil climb it makes me wonder if there is another reason for the climb in price. I've heard many investment brokers state that correct price of oil, based on supply and demand, should be some where around $80-$90/barrel. My thoughts are this "What better way to make the world shift to alternate fuels then to make fuel so expensive that the public would be willing to except change on a mass scale."