thumbnail

Resource-assessment perspectives for unconventional gas systems

American Association of Petroleum Geologists Bulletin

By:

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time

Abstract

Concepts are described for assessing those unconventional gas systems that can also be defined as continous accumulations. Continuous gas accumulations exist more or less independently of the water column and do not owe their existence directly to the bouyancy of gas in water. They cannot be represented in terms of individual, countable fields or pools delineated by downdip water contacts. For these reasons, traditional resource-assessment methods based on estimating the sizes and numbers of undiscovered discrete fields cannot not be applied to continuous accumulations. Specialized assessment methods are required. Unconventional gas systems that are also continous accumulations include coalbed methane, basin-centered gas, so-called tight gas, fractured shale (and chalk) gas, and gas hydrates. Deep-basin and bacterial gas systems may or may not be continuous accumulations, depending on their geologic setting. Two basic resource-assessment approaches have been employed for continous accumulations. The first approach is based on estimates of gas in place. A volumetric estimate of total gas in place is commonly coupled with an overall recovery factor to narrow the assessment scope from a treatment of gas volumes residing in sedimentary strata to a prediction of potential additions to reserves. The second approach is based on the production performance of continous gas reservoirs, as shown empirically by wells and reservoir-simulation models. In these methods, production characteristics (as opposed to gas in place) are the foundation for forecasts of potential additions to reserves.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Resource-assessment perspectives for unconventional gas systems
Series title:
American Association of Petroleum Geologists Bulletin
Volume
86
Issue:
11
Year Published:
2002
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1993
Last page:
1999
Number of Pages:
7