Comparative study of aggregations under different dependency assumptions for assessment of undiscovered recoverable oil resources in the world

  • Robert A. Crovelli


The U.S. Geological Survey assessed all significant sedimentary basins in the world for undiscovered conventionally recoverable crude-oil resources. Probabilistic methodology was applied to each basin assessment to produce estimates in the form of probability distributions. Basin probability distributions were computer aggregated to produce resource estimates for the entire world. Aggregation was approximated by a three-parameter lognormal distribution by combining the first three central moments of basin distributions. For purposes of experiment and study, world aggregation was conducted under four different sets of assumptions. The four cases are (1) dependent assessments of all basins, (2) dependent assessments within continental areas, but independent assessments among continental areas, (3) dependent assessments within countries, but independent assessments among countries, and (4) independent assessments of all basins. Mean estimate remained the same in all four cases, but the width of interval estimate formed using the 95th and 5th fractiles decreased with reduced dependency in going from first to fourth case.

Key words

Oil resources probabilistic methodology resource appraisal computer aggregation world estimates 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Crovelli, R. A., 1984, U.S. Geological Survey probabilistic methodology for oil and gas resource appraisal of the United States: Jour. Math. Geol., v. 16, no. 8, p. 797–808.Google Scholar
  2. Dolton, G. L., Carlson, K. H., Charpentier, R. R., Coury, A. B., Crovelli, R. A., Frezon, S. E., Khan, A. S., Lister, J. H., McMullin, R. H., Pike, R. S., Powers, R. B., Scott, E. W., and Varnes, K. L., 1981, Estimates of undiscovered recoverable conventional resources of oil and gas in the United States: U.S. Geol. Sur. Cir. 860, 87 p.Google Scholar
  3. Ford, C. E. and McLaren, R. A., 1980, Methods for obtaining distributions of uranium occurrence from estimates of geologic features: Oak Ridge, Tenn., K/CSD-13, Union Carbide, Computer Services Division, 121 p. (1 microfiche).Google Scholar
  4. Masters, C. D., Root, D. H., and Dietzman, W. D., 1983, Distribution and quantitative assessment of world crude-oil reserves and resources: U.S. Geol. Sur. Open-File Rep. 83-728, 11 p.Google Scholar

Copyright information

© Plenum Publishing Corporation 1985

Authors and Affiliations

  • Robert A. Crovelli
    • 1
  1. 1.U.S. Geological SurveyDenverUSA

Personalised recommendations