Offshore Oil and Gas Resources:

Differences in Estimates by Interior and Industry for Offshore California

RCED-86-179BR: Published: Jul 10, 1986. Publicly Released: Jul 21, 1986.

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Pursuant to a congressional request, GAO examined the procedures and assumptions the Department of the Interior and the petroleum industry used to develop estimates of offshore oil and gas resources in federal lands off California.

GAO found that: (1) the department's Minerals Management Service (MMS) uses a computer model to estimate the potential volume and value of offshore energy resources in a given area; (2) the model's outputs are considered conditional estimates of the quantities of offshore resources in a given area; (3) the oil industry's methods for estimating offshore resources are essentially the same as those MMS uses; (4) many industry sources consider their resource estimation methods proprietary; (5) the accuracy of any offshore resource estimate depends on the amount, type, and quality of available geophysical and other data; (6) MMS estimated in 1984 that the unleased federal lands off California contain the equivalent of 2.47 billion barrels of oil; and (7) an oil industry source estimated in 1985 that the same lands contain the equivalent of 5 billion barrels of oil.

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