The Atlantic has a look at the stalling price of petrol in the US - Why Are Gas Prices Falling?.
During the big run up in oil and gas prices that you can see in the charts above, some analysts contended that we were up against a geophysical limit on how much oil could be produced. It wasn't that we were running out of oil, but that we wouldn't be able to produce more, even if demand went up.
So far, however, that has not proven to be the case ...
That said, oil is getting harder to find and extract, requiring greater and greater investments of time, money, and energy. That's why, despite the relatively sunny outlook in latest edition of the IEA's World Energy Outlook, the agency cautioned that the "new oil resources" do not "mean the world is on the verge of an era of oil abundance."