Evolution of permeability in coal to sorbing gases - A preliminary study

Shugang Wang, Derek Elsworth, Jishan Liu

Research output: Contribution to conferencePaperpeer-review

5 Scopus citations

Abstract

We report laboratory experiments to investigate the permeability evolution of a bituminous coal as a function of applied stresses, pore pressure, and deviatoric stress. Experiments are conducted on 2.5 cm diameter, 2.5-5 cm long cylindrical samples, from the Powellton coal seam, West Virginia. We use a triaxial apparatus at confining stresses ranging from 6 to 10 MPa and axial stresses of 6 -18 MPa. A pressure transient method is used to measure permeability to an inert gas (Helium), a slightly adsorbing gas (Nitrogen), and a significantly adsorbing gas (Carbon dioxide). When pore pressure is kept constant, increasing effective stress causes a reduction in permeability attributed to cleat closure. An increase in deviatoric stress can either reduce or enhance the permeability depending on whether its magnitude is high enough to generate new fractures or low enough to only close the existing cleats. Under invariant total stress, increasing pore pressure increases the permeability to the inert gas (He) but decreases permeabilty to adsobing gases at low pressures and increases permeabilities at high pressures - this behavior is attributed to the competition between coal swelling and changes in effective stress.

Original languageEnglish (US)
StatePublished - Dec 1 2010
Event44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium - Salt Lake City, UT, United States
Duration: Jun 27 2010Jun 30 2010

Other

Other44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium
CountryUnited States
CitySalt Lake City, UT
Period6/27/106/30/10

All Science Journal Classification (ASJC) codes

  • Geology
  • Geotechnical Engineering and Engineering Geology

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