Summary
As conventional gas (CG) resources are depleted, unconventional gas (UG)
resources (gas from tight sands, coalbeds, and shale) are becoming increasingly
important to US and world energy supply. The volume of UG resources is
generally unknown in most basins outside North America. However, in many mature
North American basins, UG resources have been produced for decades, and
resources and reserves are well characterized. The objective of this work was
to determine the quantitative relations between known conventional and
unconventional hydrocarbon resources in mature North American basins, with the
ultimate goal of using these relations to estimate UG resources in frontier
basins outside North America.
We used assessments by the US Geological Survey (USGS), Potential Gas
Committee (PGC), Energy Information Administration (EIA), National Petroleum
Council (NPC), and Gas Technology Institute (GTI) to evaluate relations among
hydrocarbon-resource types in the Appalachian, Black Warrior, Greater Green
River, Illinois, San Juan, Uinta-Piceance, and Wind River basins. We chose
these seven basins for initial analysis of relations between CG and UG
resources because they are mature basins for both conventional and
unconventional oil and gas production. To conduct this analysis, we wrote a
computer program that we call Petroleum Resources Investigation Summary and
Evaluation (PRISE). Input data for PRISE, obtained from published data sources
and resource assessments, were values of technically recoverable resources,
consisting of the following resource categories: (1) cumulative production, (2)
proved reserves, (3) probable and possible reserves and contingent resources
(PPC), and (4) prospective resources. We then analyzed these data in each of
the seven basins to assess the relationship between conventional- and
unconventional-resource volumes.
For the seven basins studied, we found that approximately 10 - 20% of the
total recoverable hydrocarbon resources are conventional oil (CO) and CG,
whereas 80 - 90% of the recoverable hydrocarbons are UG resources. We suggest
that the results of this study may be used to estimate recoverable resources
from UG reservoirs in frontier basins worldwide, where CO and CG resources are
known but UG resources have not been evaluated.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
9 July 2009
- Meeting paper published:
12 October 2008
- Manuscript approved:
30 March 2010
- Published online:
27 April 2010
- Version of record:
27 April 2010