Well, oil prices do not exactly subscribe to the basic laws of supply and demand.
First there is OPEC.
Second, for the rest of the world, oil supply is an oligopoly. There is NO price competition per se. We have less than half of the gasoline brands compared to 20 years ago. And even fewer refiners.
Third, we are oil dependent: we screwed ourselves by having no alternatives to a lot of the essential equipment of daily life.
If we all conserve energy: drive less, drive more economically... i.e. consume less oil, then I would imagine the overall oil consumption growth is declining.
For the oil companies to maintain profit levels in a declining market, there is only one way to go -- increase oil prices.
Since there is no immediate effective alternative to oil (for cars, planes, etc.) they can raise the price slowly, until an alternative is available on the market.
(or when there is a revolt, which ever comes first.)