Figure 5: Worldwide Oil Distribution

Since exploration for oil began during the early 1860s, some 50,000 oil fields have been discovered. More than 90 percent of these fields are insignificant in their impact on world oil production. The two largest classes of fields are the super-giants, fields with 5 billion or more barrels of ultimately recoverable oil, and world-class giants, fields with 500 million to 5 billion barrels of ultimately recoverable oil. Fewer than 40 supergiant oil fields have been found worldwide. The Arabian-Iranian sedimentary basin in the Persian Gulf region contains two- thirds of these supergiant fields. The remaining super-giants are distributed as follows: two in the United States, two in Russia, two in Mexico, one in Libya, one in Algeria, one in Venezuela, and two in China.

The nearly 280 world-class giant fields thus far discovered, plus the super-giants, account for about 80 percent of the world’s known recoverable oil. There are, in addition, approximately 1,000 known large oil fields that initially contained between 50 million and 500 million barrels. These fields account for some 14 to 16 percent of the world’s known oil. Major oil fields are listed below:

♤ Ghawar field – Saudi Arabia

♤ Burgan field – Kuwait

♤ Azeri-Chirag-Guneshli – Caspian Sea, Azerbaijan

♤ Ku-Maloob-Zaap – Mexico

♤ Zakum - UAE

♤ Ferdows field – Iran

♤ Sugar Loaf field – Brazil

♤ Bolivar Coastal field – Venezuela

World’s five largest offshore oilfields:

♤ Safaniya oilfield – Persian Gulf, Saudi Arabia

♤ Upper Zakum oilfield – Persian Gulf, UAE

♤ Manifa oilfield – Persian Gulf, Saudi Arabia

♤ Kashgan oilfield – Caspian Sea, Kazakhstan

♤ Lula Oilfield - Brazil

According to current estimates, more than 81% of the world's proven oil reserves are located in OPEC Member Countries, with the bulk of OPEC oil reserves in the Middle East (figure 6). OPEC Member Countries have made significant additions to their oil reserves in recent years. As a result, OPEC's proven oil reserves currently stand at 1,200.83 billion barrels.