Journal of Canadian Petroleum Technology
Volume 50,
Number 5,
May 2011,
pp. 23-31
Summary
One of the horizons of interest for future unconventional-resource
development is deep- (> 5,000 ft) coalbed-methane (CBM) production.
Unfortunately, coal permeability is highly sensitive to changes in stress,
leading to the belief of limited permeability in deep coals. However, this
conclusion is generally based on the assumption of constant pore-volume (PV)
compressibility of a coal's porosity/cleat system during changing stress
conditions.
Modelling the evolution of permeability within potential deep coal
reservoirs is highly dependent on this assumption of constant or variable PV
compressibility. This paper shows how this assumption affects modelled
permeability changes and that permeability in deep coals may maintain much
higher values during production than previously suggested. Using prior work and
data, ideas are reorganized into an alternative view of deep-CBM
permeability.
The modelled compressibility and permeability results are then applied to
the simulation of deep-CBM reservoirs to discover the practical difference of
the compressibility assumption on a coal's simulated production. Simulations
show significant difference in production based on the two assumptions.
Application of the simulation results may provide a justification for
exploration into deeper CBM reservoirs.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
15 December 2010
- Meeting paper published:
20 October 2010
- Manuscript approved:
1 February 2011
- Published online:
22 April 2011
- Version of record:
2 May 2011
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