Modeling Permeability in Coal Using Sorption-Induced Strain Data [electronic resource].
- Washington, D.C. : United States. Dept. of Energy, 2005. and Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
- Additional Creators:
- Idaho National Laboratory, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
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- Free-to-read Unrestricted online access
- Sorption-induced strain and permeability were measured as a function of pore pressure using subbituminous coal from the Powder River basin of Wyoming, U.S.A. and high-volatile bituminous coal from the Uinta basin of Utah, U.S.A. We found that for these coal samples, cleat compressibility was not constant, but variable. Calculated variable cleat-compressibility constants were found to correlate well with previously published data for other coals. Sorption-induced matrix strain (shrinkage/swelling) was measured on uncon-strained samples for different gases: carbon dioxide, methane, and nitrogen. During permeability tests, sorption-induced matrix shrinkage was clearly demonstrated by higher perme-ability values at lower pore pressures while holding overbur-den pressure constant; this effect was more pronounced when gases with higher adsorption isotherms such as carbon dioxide were used. Measured permeability data were modeled using three different permeability models that take into account sorption-induced matrix strain. We found that when the measured strain data were applied, all three models poorly matched the measured permeability results. However, by ap-plying an experimentally derived expression to the strain data that accounts for the constraining stress of overburden pres-sure, pore pressure, coal type, and gas type; two of the models were greatly improved.
- Published through SciTech Connect., 10/01/2005., "inl/con-05-00508", "SPE 97068", 2005 SPE Annual Conference and Technical Exhibition,Dallas, Texas, U.S.A.,10/09/2005,10/12/2005., and Richard L. Christiansen; Eric P. Robertson.
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