Advancing methods of pumping and refining have managed to allow the petroleum industry to keep pace with rising demand over the years. So, although Xcel raises a good point regarding supply/demand, that is not a factor in the recent uptrend in petroleum prices.
The real factor is an administration that has lined it's own pockets at the expense of the average citizen. I'll explain EXACTLY how in a second, but first the setup.
When Presidents and their upper-level administrators take office they are required to disgorge any personal investment holdings or they must turn over their holdings to a third-party administrator who can ensure that there is no conflict of interest in Presidential politics and the President's personal finances (and Vice-President, etc.).
But, when Bush & Co. took office he OVERRULED that Congressional mandate thereby keeping his vast portfolio of Oil and Petroleum Industry stocks. Same holds true for VP Cheney, and most of the administration - in fact, Coldoleeza Rice holds enough Chevron stock to have an oil barge named after her! It's true - it's the "Condoleeza" and it's in Iraq right now.
The Bush administration became the first administration in our nation's history to have a strong financial interest in the petroleum industry - specifically the rise in the price of oil (and gas) equates directly to the rise in the personal net worth of our "leaders".
Even dating back to 2000, conservative (and often Republican-funded) think tanks such as the Brookings Institute and the Carlyle Group cited extreme conflicts of interest by tying the President's pocket to the price of oil.
In fact, according to the Brookings Institute, for every .01 cent rise in the price of regular unleaded gasoline:
President Bush's net-worth increases by $146,000 ANNUALLY
VP Cheney's net-worth increases by $220,000 ANNUALLY
Since the start of Bush's Presidency, his personal net-worth has more than quadroopled to over $2 Billion and VP Cheney's has increased five-fold to over $5 Billion. Since they get paid about $100,000 a year and since the stock market is relatively flat over the same time frame, the enormous growth is directly attributed to the increase in the value of their petroleum industry interests.
Famous economist Adam Smith theorized that wealth is never created, it simply changes hands. So, we as a country have subsized the wealth transfer from our pockets to the Bush Boy's pockets - and we continue to do so.