Luncheon – September 21, 2001

Title: Future Oil and Gas Resources of the World-Unresolved Issues

Speaker: Thomas S. Ahlbrandt, USGS, Denver, CO,

Date: September 21, 2001

Publication: The Outcrop, September 2001, p. 4, 15

Is the world running out of oil? Where will future oil and gas supplies come from? The U.S. Geological Survey completed a new assessment in 2000 of the undiscovered conventional oil and gas resources of the world to help answer these questions. One hundred and twenty-eight provinces were assessed. These included 76 priority provinces containing 95% of the world’s known discovered oil and gas and an additional 52 boutique provinces, some of which may be highly prospective. Total Petroleum Systems (TPS) were identified and described for each of these provinces along with their assessment units (AU) which are the basic units for assessing undiscovered petroleum. Total Petroleum Systems and contained AU extend into portions of 35 other provinces. The assessment process coupled geologic analysis with a probabilistic methodology to estimate remaining potential. Within these 128 provinces, 159 TPS and 274 AU were assessed. An additional 57 boutique provinces have been recently identified for assessment in the next phase of the project.

In addition to the conventional estimates, future reserves will be augmented by the phenomenon known as field growth. Field growth estimates for known fields will likely be large with volumes comparable to estimates for undiscovered resources. Several field growth algorithms were utilized in the new assessment to capture the uncertainty associated with this critical component of any analysis of world oil and gas supply. Detailed, basin-level, reserve growth studies have been completed in the Volga-Ural and West Siberian Basins and are underway in the North Sea, selected western Canadian basins, and the Middle East.

Analysis of the petroleum systems of the world provides surprising geologic insights into the volumes of known and undiscovered petroleum that were assigned to depositional environments of reservoirs, source rock ages and their levels of thermal maturation, trap styles, and seals. Much of the world’s future undiscovered potential remains offshore, and the Arctic basins remain the great frontier for undiscovered resources.

Non-conventional oil and gas are quite common in the petroleum provinces of the world and represent a significant resource yet to be fully developed. Seventeen non-conventional AU, of coal-bed methane, basin-center gas, continuous oil, and gas hydrate occurrences, were identified and captured digitally for a future assessment effort. Initial efforts to assess heavy oil deposits and other non-conventional oil and gas deposits are underway.

Digital products from the World Energy Project include: 1) the USGS World Petroleum Assessment 2000 in a 4 CD-ROM set that was published as USGS Digital Data Series 60, 2) 9 CD-ROMs that contain geologic maps of most of the world, 3) one CD-ROM ranking the world’s oil and gas provinces, and 4) individual reports of Total Petroleum Systems for provinces which are downloadable at