Summary
Petrographic work on thin sections from rock samples collected in tight gas
sandstones of the western Canada sedimentary basin (WCSB) shows that the
sandstones are composed of intergranular, microfracture and slot, and isolated
noneffective porosities. The petrographic observations of these triple-porosity
rocks have led to a petrophysical interpretation with the use of a
triple-porosity model.
Tight gas reservoirs are very complex heterogeneous systems that have been
evaluated in the past mostly with single-porosity models. We propose that these
types of reservoirs can be represented better by triple-porosity models for
more rigorous quantitative petrophysical characterization. The triple-porosity
model discussed in this paper fits the petrographic observations very well,
leading to a more rigorous characterization of effective and noneffective
porosity.
The petrographic and core-calibrated triple-porosity model is then used for
well-log interpretation of those wells when these data are not available. The
result is a reasonable quantitative characterization of the tight gas reservoir
that can be used for improving hydraulic-fracturing design, flow-units
determination, reservoir engineering, and simulation studies. The data can be
determined at room conditions and simulated conditions of net stress.
It is concluded that honoring with a triple-porosity model the different
types of porosities observed in thin sections and cores leads to more-rigorous
and -useful petrophysical interpretations that can be linked to gas
productivity.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
10 April 2011
- Meeting paper published:
8 May 2011
- Manuscript approved:
14 July 2011
- Published online:
5 October 2011
- Version of record:
13 October 2011
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