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The AAPG/Datapages Combined Publications Database

CSPG Special Publications


Facts and Principles of World Petroleum Occurrence — Memoir 6, 1980
Pages 283-300
Petroleum Exploration and Assessment

Conventional Petroleum Assessments: Facts and Fallacies

J. R. Century


Assessments of North American conventional oil and gas have served a useful purpose in documenting some of our long term supply problems. The geological surveys of Canada and the U S. A. have played key roles in preparing assessments used in defining public energy policies. Since similar techniques have been adopted by both countries, it is important to evaluate the methodology reliability.

Probabilistic techniques were first utilized by major oil companies for in-house objectives that emphasized giant fields; these techniques later were adapted by government agencies. However, a number of misconceptions are inherent in probabilistic estimates of established basins and plays that bias assessments and result in unwarranted pessimism.

Independent analysis by the author results in the estimate that at least 4.8 × 109m3 (30 billion barrels) of oil and 5.6 × 1012m3 (200 trillion cubic feet) of natural gas will ultimately be produced from the western Canadian provinces. These figures are double the estimates made by government and most major companies.

The following factors are believed to have contributed to fallacies in recent assessments: 1. Under-utilization of available public data; 2. Minimal contribution attached to supplies from smaller fields and incremental growth through drilling; 3. Restricted use of drilling data relationships in predicting major discoveries; 4. Limited view of comparative geologic and development models; 5. Misjudged value of exploration and production technology in developing supplies; 6. Negative versus positive geological emphasis; 7. Neglect of the price and incentive variable; 8. Major versus independent company efficacy.

Several described oil and gas plays are part of a current significant trend of increasing supplies from the Western Canadian Sedimentary Basin: The Nisku Formation carbonate pinnacle trend in the Upper Devonian oil habitat of the Pembina area and elastics in the Lower Cretaceous Mannville Group gas habitat of the Elmworth-Deep Basin area. The Upper Cambrian Deadwood Sand in the Lower Paleozoic oil habitat of the Williston Basin is a third example of developing potential in North Dakota. The success of these plays confirms optimistic assessments of conventional oil and gas habitats in the western Canadian provinces originally documented in 1973 and since presented at various technical conferences.

An acceptable Canadian strategy to marketing surplus oil and gas supplies depends on realistic assessments. The eclectic and holistic method of analysis described in this paper will help in the solution of the North American energy supply problem.

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