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 O00 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.
AND DEFINITIONS World Ultimate Resources of conventional crude oil and natural gas remain interpreted as being about 2300 billion barrels (370 Gm3) of oil (BBO) and 12000 trillion cubic feet (TCF) (340 Tm3) of gas.
These two values are approximately equal in energy.
Some researchers have considered that the 12000 TCF value most certainly is low because source opportunities for gas are so much greater than for oil including the thermal conversion from oil to gas.
Mindful of this, we have tried to increase gas resource values, but considering the sensitivity of gas entrapment to sealing rocks and faulting, it has been difficult to determine from where greatly increased values might derive.
Unconventional resources, such as extra heavy oils, tar sands, gas in tight sands, and coal bed methane are not herein considered but they must, nonetheless, be recognized as being present in very large quantities. They are, however, expensive to recover at adequate rates of production, and sometimes expensive to alter to the quality necessary for modern day use. We don't know how, if, or when they will become major components of world energy consumption but certainly their development must be tracked carefully for signs of economic life or political/economic preference. The two major sources of unconventional oil, most rec