Abstract
The occurrence and quantity of world petroleum resources appears to be well understood. The numbers are so great, however, that even minor variants in the total picture can be responsible for enormous localized industrial activity. Specific knowledge of the widespread local occurrences of oil and gas, therefore, is important to economic development and to the free market distribution of energy. It is also clear, however, that a large proportion of the recoverable petroleum resources are found in only a few selected localities.
We believe that, worldwide, recoverable conventional oil and gas exist in ultimate quantities approximating 2300 billion barrels (370 Gm3) of oil and 12 000 trillion cubic feet (340 TM3) of gas. These values are limited by our concepts of world petroleum geology and our understanding of specific basins; nonetheless, continued expansion of exploration activity, around the world, has resulted in only minimal adjustments to our quantitative understanding of ultimate resources.
Reserves reporting has been one of the greatest hindrances to a thorough understanding of world resources because we are just now gaining an understanding of field growth and what is actually being calculated and reported from various localities.
Unconventional resources are present in large quantities, in particular in the Western Hemisphere, and are of a dimension to substantially contribute to world reserves should economic conditions permit.
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