"With daily global demand roughly 85 million barrels per day, the world's oil producers have less than 2 million barrels per day of spare production capacity, and most of that is for Saudi blends of oil that are less ideal for manufacturing transportation fuels.
Oil traders are nervous about geopolitical tensions ranging from violence in Nigeria to the West's nuclear standoff with Iran to the move toward greater nationalization of natural resources in energy-rich Venezuela.
The global economy is expanding, and that means the thirst for oil is only going to grow.
Speculative investors are piling into energy markets as a way to profit from soaring prices and geopolitical turmoil that could potentially be bad for equities prices."
http://www.chron.com/cs/CDA/printstory.mpl/business/energy/3817761
You nailed it. Check the weekly open interest summary. Two weeks ago it was one million contracts.