Stress-dependence of the permeability and porosity of sandstone and shale from TCDP Hole-A

Jia Jyun Dong, Jui Yu Hsu, Wen Jie Wu, Toshi Shimamoto, Jih Hao Hung, En Chao Yeh, Yun Hao Wu, Hiroki Sone

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242 Citations (Scopus)

Abstract

We utilize an integrated permeability and porosity measurement system to measure the stress dependent permeability and porosity of Pliocene to Pleistocene sedimentary rocks from a 2000m borehole. Experiments were conducted by first gradually increasing the confining pressure from 3 to 120MPa and then subsequently reducing it back to 3MPa. The permeability of the sandstone remained within a narrow range (10-14-10-13m2). The permeability of the shale was more sensitive to the effective confining pressure (varying by two to three orders of magnitude) than the sandstone, possibly due to the existence of microcracks in the shale. Meanwhile, the sandstone and shale showed a similar sensitivity of porosity to effective pressure, whereby porosity was reduced by about 10-20% when the confining pressure was increased from 3 to 120MPa. The experimental results indicate that the fit of the models to the data points can be improved by using a power law instead of an exponential relationship. To extrapolate the permeability or porosity under larger confining pressure (e.g. 300MPa) using a straight line in a log-log plot might induce unreasonable error, but might be adequate to predict the stress dependent permeability or porosity within the experimental stress range. Part of the permeability and porosity decrease observed during loading is irreversible during unloading.

Original languageEnglish
Pages (from-to)1141-1157
Number of pages17
JournalInternational Journal of Rock Mechanics and Mining Sciences
Volume47
Issue number7
DOIs
Publication statusPublished - 2010 Oct 1

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Keywords

  • Effective confining pressure
  • Permeability
  • Porosity
  • Specific storage
  • Stress history

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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