Thomas S. Ahlbrandt¹
(1) United States Geological Survey, Denver, CO

Abstract: The USGS world oil and gas assessment

The USGS is completing a new assessment of the technically recoverable undiscovered oil and gas resources of the world to be released at the World Petroleum Congress in Calgary in June 2,000. Assessments will be completed by a team of over 30 geoscientists by the end of the calendar year 1999. Petroleum systems are identified and assessed using a probabilistic methodology coupled with geologic analysis. Nearly 1,000 provinces were defined and petroleum resources allocated to 409 of these. A total of 76 priority provinces containing 95% of the world’s known oil and gas and 26 boutique, or highly prospective, provinces are being assessed. Based upon our initial analyses, several observations are clear. First, our estimates of undiscovered technically recoverable oil resources will not differ greatly from those of the 1994 USGS assessment; however, estimates of both natural gas and natural gas liquid resources will be larger than previous estimates. In addition, field growth estimates of known fields will likely be large and several algorithms will be utilized to encompass uncertainty associated with this critical component of any analysis of world oil and gas supply. A production plateau concept of reserve development rather than a bell shaped (or Hubbert) production profile is advocated and is linked to the concept of field growth. Continuous or unconventional oil and gas resources have been captured digitally for a future assessment effort, and represent a significant future resource. A series of digital products including geologic maps of the world as well as petroleum system write-ups have been made available via the CD-ROM and the internet. These digital products and the methodology employed in the assessment have been favorably reviewed by the National Academy of Science (NRC), AAPG and GIS World.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana