Its not a supply problem. There is plenty of oil.
Its a speculation problem cause there is plenty of money to be made in the price of oil. There are very few parts of the market that have turned a profit all time for the last 10 years. So people are turning away from bond and mrtg back securities and are investing in oil futures. Thats where the price increase is.
Think about it. Our demand has been shrinking in the US since this spring. This is not the heating season and the US has had the biggest drop in highway miles driven since the 70s. But the price per barrel has still increase cause there are people willing to bid it up to get in on the action. Same as our housing bubble, etc. As long as there maybe a profit to be turned people will buy in.