Onshore, Offshore, and Country Allocations
2005. "Onshore, Offshore, and Country Allocations", 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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Economics of onshore petroleum exploration and production are very different from offshore. In the assessment process, allocations of estimated undiscovered volumes were made to onshore and offshore locations (where applicable) in order to enhance the utility of the results for further economic analysis. Offshore areas were deemed those that required offshore infrastructure, in either fresh or salt water.
Estimated volumes of onshore and offshore undiscovered oil by region (excluding the U.S.) are shown in Figure 96; of undiscovered natural gas, in Figure 97; and of NGL, in Figure 98. Most of the onshore undiscovered resources are expected to be in Regions 1 (Former Soviet Union) and 2 (Middle East and North Africa). Figure 99 shows that, at the world level, approximately equal amounts of each of the three undiscovered commodities are expected to be onshore and offshore. Figure 100 shows that for Regions 3 through 8, about one-fourth of the undiscovered volume of each commodity is expected to be onshore and nearly three-quarters of the potential is offshore. The offshore potential of each assessment unit (AU), total petroleum system (TPS), and province and the water depths associated with the offshore portion for each AU, is documented in USGS (2000). Most offshore provinces extend to water depths of 6562 ft (2000 m) with the exception of areas where exploration has already begun in deeper water depths. For example, the water depth limits of the AU were extended to 13,123 ft (4000 m) in the Campos Basin
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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.