Summary
Most estimates of the resource endowment [original gas in place (OGIP)]
reported for world unconventional gas start with Rogner's top-down study
(Rogner 1997). That global estimate is most likely quite conservative because
the oil and gas industry has discovered enormous volumes of shale gas around
the world since the 1990s. The data from these new reservoirs add substantially
to our understanding of the unconventional resource base. Furthermore, the
uncertainty of Rogner's assessment was not quantified. Thus, considering the
uncertainty, a new assessment of original unconventional gas in place worldwide
is needed.
The objective of this project was to estimate the probabilistic
distributions of original volumes of gas trapped in coalbed, tightsand, and
shale reservoirs worldwide. To accomplish this objective, we reviewed published
assessments of coal and conventional and unconventional resources and
established the quantitative relationship between unconventional gas [coalbed
methane (CBM), tight-sands gas, and shale gas] and the conventional hydrocarbon
(coal, conventional gas, and oil) resource endowments for North America. Then,
we used this relationship to extrapolate original unconventional gas in place
worldwide. Our assessment of the world resource endowment established an
unconventional OGIP of 83,400 Tcf (P10) to 184,200 Tcf (P90), which is 2.6 to
5.7 times greater than Rogner's estimate of 32,600 Tcf.
Our regional assessments of unconventional OGIP should help industry better
target its efforts to rapidly accelerate the development of unconventional gas
resources worldwide. The methodology used to assess the distribution of each
type of unconventional OGIP may be used to estimate unconventional gas
resources at the country or basin level, given knowledge of the coal in place
and technically recoverable resources of conventional hydrocarbons.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
14 October 2011
- Meeting paper published:
16 November 2011
- Revised manuscript received:
5 April 2012
- Manuscript approved:
19 July 2012
- Published online:
23 October 2012
- Version of record:
2 November 2012
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