5. Burgan
> Country: Kuwait
> Est. Total Resource: 150 billion barrels
> Est. Remaining: 6-25 billion barrels
> Discovery Date: 1938

Burgan, Kuwait’s largest field, resembles the number four field on our list, Ghawar, in its massive size. But unlike Ghawar, it fails the longevity test. Production from Burgan has fallen since the 1991 Gulf War ended, when retreating Iraqi troops set fire to some 700 wells in the field and an estimated 600 million barrels of oil went up in smoke. The field has never recovered and officially entered depletion in late 2005. The fires, coupled with the feckless Kuwaiti government, likely will have the second largest conventional field ever found dry in the next decade or so. Accurate and independently verified numbers on Burgan are not available.

4. Ghawar
> Country: Saudi Arabia
> Est. Total Resource: 162 billion barrels
> Est. Remaining: 11-45 billion barrels
> Discovery Date: 1948

Ghawar is the undisputed heavyweight champion of conventional oil fields. Since beginning production in 1951, the field has given up an astounding 55 billion barrels or so, and still produces at around 5 million barrels/day. Production is enhanced by water-flooding, with about 7 million barrels of seawater pumped into the field every day to force the oil out. The Saudis believe that Ghawar can produce another 125 billion barrels, more than twice its total production after 60 years. There has been no independent verification of any Saudi field since the country fully nationalized its oil resources in 1975, and there is a lot of skepticism over the Saudis’ claims for Ghawar. Still, it could easily rank as the eighth wonder of the world.

3. The Alberta Oil Sands
> Country: Canada
> Est. Total Resource: 173 billion barrels
> Est. Remaining: 169 billion barrels
> Discovery Date: 1980

The Western Canada Sedimentary Basin covers about 540,000 square miles and contains a total of 173 billion barrels of resource in what are called oil sands. Unlike the shales in the American Piceance and Uinta Basins, the Canadian oil sands are already being mined and refined into conventional oil. There are more than 20 active projects in the province of Alberta, most located near Fort McMurray, site of the largest of the three oil sands deposits in the WCSB.

2. The Orinoco Belt
> Country: Venezuela
> Est. Total Resource: 1.3 trillion barrels
> Est. Remaining: 530 billion barrels
> Discovery Date: 1930s

The Orinoco Belt in Venezuela is estimated to hold some 1.3 trillion barrels of oil in place, according to a recent survey by the U.S. Geological Survey. Venezuela now claims it has 297 billion barrels of total reserves, putting it ahead of Saudi Arabia, which is estimated to hold reserves of 265 billion barrels. The Orinoco Belt contains both a heavy sulfurous oil and deposits of tarry oil sands similar to the Canadian variety, though somewhat less viscous. It is nasty stuff, but there is lots of it. In fact, only a bit more than a third of the total is recoverable by today’s technology and economic requirements.

1. The Piceance & Uinta Basins
> Country: USA
> Est. Total Resource: 2.855 trillion barrels
> Est. Remaining: 2.855 trillion barrels
> Discovery Date: 1912

The Piceance and Uinta Basins in western Colorado and eastern Utah are estimated to hold oil shale in place of 1.525 trillion barrels and 1.32 trillion barrels, respectively. The catch is that the stuff is not really oil at all, but rock containing kerogen, a precursor to oil. In a few hundred million years the rock would be converted to flowing oil naturally, if it were left alone. These basins, along with another in southern Wyoming, were added to the U.S. Naval Petroleum and Oil Shale Preserves in 1912, although Native Americans had used the flammable rocks for centuries. The total area covered by the deposits is about 16,000 square miles, an area larger than the states of New Jersey and Connecticut combined. Whether the oil shales are ever developed depends largely on the price of crude and how much environmental impact people are willing endure.

Paul Ausick