2005. "Conclusions", Global Resource Estimates from Total Petroleum Systems, Thomas S. Ahlbrandt, Ronald R. Charpentier, T. R. Klett, James W. Schmoker, Christopher J. Schenk, Gregory F. Ulmishek
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The USGS World Petroleum Assessment 2000 (USGS, 2000) provides estimates of the quantities of conventional oil, natural gas, and natural gas liquids outside the United States that have the potential to be added to reserves in the next 30 years (1995 to 2025). Excluding the U.S., the mean estimated volumes of undiscovered resources are 649 billion bbl of oil, 4669 tcf, and 207 billion bbl of NGL. The estimated mean additions to reserves from discovered fields (reserve growth) are 612 billion bbl of oil, 3305 tcf, and 42 billion bbl of NGL.
The potential additions to reserves from reserve growth are nearly as large as the estimated undiscovered resource volumes. These estimates imply that 75% of the world’s grown conventional oil endowment and 66% of the world’s grown conventional natural gas endowment have already been discovered in the areas assessed (exclusive of the U.S.). Additionally, for these areas, 20% of the world’s grown conventional oil endowment and 7% of the world’s grown conventional natural gas endowment had been produced by the end of 1995.
By way of calibration, the 8 years since 1995 are less than one-third of the 30-yr forecast span (1995–2025) for the assessment. During this period, 18% of estimated oil resources and 27% of the estimated natural gas resources have been added to reserves from new field discoveries and reserve growth for the provinces assessed in USGS (2000). If the entire world is considered, exclusive of the U.S. and Canada, these percentages increase to 23% of
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Presented in this publication are the results of a major study of the petroleum resources of the world as analyzed by total petroleum systems. The distribution and volumes of resources available in these systems are critically important for the future of the world's economies.Â Geologic insights gained from studying these 149 systems and their constituent assessment units in 128 provinces and 96 countries, exclusive of the United States, allow a new look at petroleum accumulations and the rocks that are intimately associated with them. The geographic distributions of oil and natural gas systems show significant differences. Lists of new areas of potential and new estimates of resources make this a must-have addition to the petroleum geologist's library.