--> ABSTRACT: USGS Strategy for Assessment of European Gas Shales, by Gautier, Donald L.; #90135 (2011)

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USGS Strategy for Assessment of European Gas Shales

Gautier, Donald L.1
(1)MS 969, U.S. Geological Survey, Menlo Park, CA.

In cooperation with European geoscience organizations, the United States Geological Survey (USGS) has begun an assessment of potential additions to reserves from continuous-type gas and oil accumulations in fine-grained rocks of Europe. Development of continuous-type accumulations has transformed the energy outlook of Canada and the United States and the degree to which such accumulations can be developed outside North America may determine the future of European and global energy markets. Unlike conventional reservoirs, continuous-type accumulations in mudstones: (1) are laterally extensive, (2) do not necessarily coincide with structural and stratigraphic traps, (3) lack well defined down-dip petroleum/water contacts, (4) do not seem to be localized by buoyancy forces, and (5) typically contain both source and reservoir in the same formation. Drawing on the geological circumstances and well performance observed in analogous North American gas shales, USGS has developed a probabilistic, geology-based methodology with which to evaluate the potential for technically recoverable natural gas and oil in continuous-type accumulations in Europe. Rather than calculating in-place resources and estimating recovery efficiencies, the current USGS methodology is performance-based. Candidate formations are screened for particular geological criteria and geologically defined assessment units (AU) are specified. Potential additions to reserves in each AU are evaluated using four input distributions: play-level risk, volumes of potentially productive formations within the AU, optimal well density, and estimated ultimate recovery per well. The four distributions are combined in a Monte Carlo simulation that yields a probability density of recoverable resources that can be further evaluated for resource/cost relationships.

 

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.