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Future Global Crude Oil Supply

L. F. Ivanhoe

Inexpensive crude oil fuels the world's economies and armies. In 1986, for the first time, the global production of crude oil and natural gas liquids exceeded new reserves added. Proved oil reserves at the end of 1985 stood at 707.6 billion bbl (BBO), but declined to 703.1 BBO by the end of 1986. The 1986 reserve decrease--4.5 BBO--was 20.4% of total global production of 22.0 BBO. This handwriting on the wall is very bad news.

The world's recoverable crude oil and natural gas liquids discovered through 1985 totaled 1,258 BBO, including cumulative production of 551 BBO and 707 BBO of reserves. At current production rates, half of all discovered oil will have been burned up by 1989. Timing of the end of our oil age can be extrapolated from a modified "Hubbert curve," with future production resembling a mirror image of past production. The watershed beginning of the inevitable decline in global crude oil supplies can be expected in the late 1990s, although the date may be over 30 years later in some "super-oily" Organization of Petroleum Exporting Countries (OPEC).

Clearly the day of reckoning will be postponed by any new oil discoveries. These will probably be distributed much as are the present global reserves (e.g., 68% OPEC; 11% USSR and China; 21% rest of world). Of this, 56% will be in the Persian Gulf area. "Giant" fields (more than 0.5 BBO reserves) contain 75% of the world's reserves. Discoveries of oil in the globe's 320 known giant fields peaked at 125 BBO during the period 1961-1965, after which giant field discoveries plunged to only 10 BBO during 1981-1985. Henceforth, we should expect to find few giant whales (but many minnows) in the non-OPEC world's fished-out basins.

Every new field will help as global crude oil supplies dwindle. Therefore, it is essential that all large prospects outside the Persian Gulf be tested promptly, so the oil-importing nations will know what size of non-OPEC reserves are available.

AAPG Search and Discovery Article #91035©1988 AAPG-SEPM-SEG Pacific Sections and SPWLA Annual Convention, Santa Barbara, California, 17-19 April 1988.