how much is left?
More than 70 percent of world oil comes from fields discovered before 1970. Simply put, there is a gap between what is being extracted (a lot) and what is being discovered (not a lot). Though production isn’t falling off a cliff, the climax in conventional (easy to extract) oil production is no secret. Unconventional sources like the Oil Sands can help, but their extraction is punishing to the environment, and costly.

global demand
Global demand for oil, now at 84 million barrels daily, continues to grow relentlessly. The US has a voracious appetite for oil, which is predicted to grow nearly 50 percent in 20 years. China is also learning to drink deep, and may be using 10 million barrels a day by 2025. Many energy analysts (Goldman Sachs, CIBC World Market )
are predicting a super-spike that could drive oil prices well over $100/barrel, and “this time there won’t be any tap that some appeased mullah or sheik can suddenly turn back on” said Jeffrey Rubin at CIBC World Markets (September 8, 2005). Though he spent some time in sensitivity training as a result.

OPEC
US consumption has climbed 25 percent since the mid-1980s, to its highest level ever. The gap between domestic production of crude oil and the consumption of products made from it is steadily widening. Imports have surged to 54 percent of the country’s oil needs. Despite growth in non-conventional crude sources in Russia, Mexico and Canada, the US government’s Energy Information Administration projects that in 20 years, the Persian Gulf will supply between one-half and two thirds of the oil on the world market. Whether or not this precipitated US incursions in Afghanistan and Iraq, US planners ostensibly believed that it would lay the groundwork for a stable, democratic Middle East perhaps putting the world’s oil supply in more trustworthy (or at least, friendly) hands. For further thought provoking material, please read Rebuilding Americas Defenses.

links
The Future of Oil
Winning the Oil Endgame
Medium-Term Oil Market Report
The End of Cheap Oil
Oil: Where It Is and How Much is Left
Plunging Into Deep Water