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This report summarizes, at the petroleum basin level, the United States Geological Survey's World Energy Program 1993 assessment of world conventional oil and gas resources. The maps provided show boundaries of petroleum basins that are referenced by the assessment, as well as, future oil and gas potential. The "Futures" or future potential of a basin is calculated as the the sum of the Identified Reserves and the modal value assigned to the conventional Undiscovered Resources. II. ASSESSMENT Assessments of Identified Reserves and Undiscovered Resources of the world were prepared for the 11th, 12th, 13th, and 14th World Petroleum Congresses (Masters and others, 1984, 1987, 1992, 1994). Table 1 and Table 2 provide components of the assessment of conventional undiscovered oil and gas resources, respectively, by country and basin. Conventional Undiscovered Resources (as used here) are oil and gas resources postulated to exist from geologic information and theory outside of known oil and (or) gas fields and that, if found, could be extracted using traditional development practices. Estimates are made without reference to economic profitability. Identified Reserves, also shown for each country and some basins in Table 1 and Table 2, include proved reserves and may also include additional petroleum that could be contributed by field growth through field extensions, revisions of reserve estimates, addition of new pools, and applications of new recovery techniques. Proved reserves are the identified resource In this report the term basin is used interchangably with province. whose existence, quantity, and commercial producibility are demonstrated by geologic evidence and supported by engineering measurements. This definition is more inclusive than the accepted US definition of proved reserves.

Geologic reasons indicate that the dominant position of the Middle East as a source of conventional petroleum will not be changed by new discoveries elsewhere. The share of world crude oil production coming from the Middle East could increase, within 10 to 20 years, to exceed 50 percent, under even modest increases in world consumption. Nonconventional resources of oil exist in large quantities, but because of their low production rates they can at best only mitigate extant trends. Increased production of natural gas outside the United States, however, offers an opportunity for geographically diversified energy supplies in the near future.

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World Demonstrated Reserves of crude oil are approximately 723 billion barrels of oil (BBO). Cumulative production is 445 BBO and annual production is 20 BBO. Demonstrated Reserves of crude-oil have declined over the past 10 years consistent with discoveries lagging production over the same period. The assessment of Undiscovered Resources shows a 90 percent probability that the amount discoverable lies between 321 and 1,417 BBO, 550 BBO being the most likely value. The most likely value for Ultimate recoverable resources is 1,718 BBO. The distribution of Ultimate Resources of crude oil will remain highly skewed toward the Middle East; no frontier areas that have potentials large enough to significantly affect present distribution are recognized. Rates of discovery have continued to decline over the past 20 years even though exploration activity has increased in recent years. Prudence dictates, therefore, that the low side of the assessment of Undiscovered Resources be responsibly considered and that alternate energy sources be a part of future planning.Extra-heavy oil and bitumen are assessed separately, with Reserves being figured as the annual productive capacity of installed facilities times 25 years. The annual production of extra-heavy oil is about 8 million barrels and of bitumen about 60 million barrels.