Declining Global Discoveries of Giant Oil Fields

L. F. Ivanhoe

Giant oil fields, those containing more than 0.5 billion bbl of recoverable conventional crude oil, are the backbone of the global oil supply. Discovered giant oil fields number only 320 worldwide, but contain over 75% of our globe's known oil. Any giant fields will be found quickly in a pristine basin regardless of the price of oil. Giant fields are the biggest targets, and are accordingly the first to be discovered in any onshore or offshore, politically-accessible basin that is shot with modern electronic digital seismic techniques.

The world's only extensive prospective areas that have not yet been covered by digital seismic nets are in Russia and onshore China, so some new giant oil fields should still be expected there. However, those countries are no longer virgin, having been already explored with reasonably effective surface geology and analog seismic methods. Production from any new giants mostly will be consumed within those nations and will not substantially affect global export markets or prices.

The discovery of new oil in the world's giant fields peaked at 125 billion bbl of oil during the five-year period from 1961 through 1965, when the total global production was 50 billion bbl of oil. This period was 10 years before the first oil price shock in 1973. Since then, the amount of new oil discovered in giant fields has dropped steadily, being only 10 billion bbl of oil during 1981 through 1985. During this time, total global production increased to over 100 billion bbl of oil. Most giant fields have now been found except in the OPEC nations of the Persian Gulf and Venezuela (which have 70% of the world's known reserves). The non-OPEC countries are no longer finding enough new oil to replace their 68% share of the globe's huge production of almost one trillion (million million gallons of crude per year--one-quarter of which is used in the United States. The world's golden century of oil has now passed its peak.

AAPG Search and Discovery Article #91024©1989 AAPG Pacific Section, May 10-12, 1989, Palm Springs, California.