Comparison of Resource Assessment Methods and Geologic Controls-- Deep Natural Gas Plays and Zones, United States and Russia

T. S. Dyman, M. D. Belonin, and M. E. Henry

Deep (greater than 4.5 km--15,000 ft) conventional natural gas resources will play a important role in the future energy needs of the United States and Russia. Deep sedimentary basins are widespread in these countries and have formed in a variety of depositional and tectonic settings. Significant volumes of undiscovered deep natural gas are in the Gulf Coast, Anadarko, Permian, and Rocky Mountain basins of the U.S., and in the Timan-Pechora, West Siberia, East Siberia, and North and South Caspian basin of the former Soviet Union.

Deep natural gas resources are regularly assessed by the All-Russia Petroleum Research Exploration Institute (VNIGRI) and the U.S. Geological Survey (USGS) as part of their normal research activities. Both VNIGRI and the USGS employ similar assessment methods involving play (or zone) analysis using geological data and based on an analysis of confirmed and hypothetical plays using field-size distributions, discovery-process models, and statistical estimation procedures that yield probabilistic estimates of undiscovered accumulations. Resource estimates for the deep structural and statigraphic plays of the Anadarko basin and deep Paleozoic zones in the Timan-Pechora basin are compared and contrasted using both methods.

Differences in results of assessments between VNIGRI and USGS arise due to (1) the way in which plays/zones are defined, (2) different geochemical models for hydrocarbon generation as applied to hypothetical plays, (3) variations in the ways in which statistical estimation procedures are applied to plays and regions, and (4) differences in economic and technologic assumptions, reserve growth calculations, and accumulation size limits and ranges.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California