Effective stress for transport properties of inhomogeneous porous rock

The Biot-Gassmann (BG) poroelasticity theory is based on the assumption of a microhomogeneous solid frame. This means that it considers the solid frame to be homogeneous at the pore-scale level. If the solid frame is built out of two or more solid constituents at the pore-scale level, then the porous rock can be considered microinhomogeneous. Although in a macroscopic sense, it still is homogeneous. Porosity changes during deformation of microinhomogeneous rocks lead to poroelastic compressibilities that are not compatible with the BG theory. The key to modeling the compressive response of microinhomogeneous rocks is the porosity perturbation equation known from the volume-averaging-based poroelasticity framework. This porosity perturbation equation entails an effective stress coefficient that can be different from unity. Only if this porosity effective stress coefficient equals unity can the porosity perturbation equation implicit to Biot’s theory be recovered. The porosity perturbation equation was reconciled with the poroelastic compressibility definitions suitable for pressure-cell experiments. These compressibilities were parameterized in terms of the porosity effective stress coefficient. The results provide a means to consistently interpret pressure-cell experiments on Berea sandstone samples in which a difference between the unjacketed bulk and pore compressibilities has been found.

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An experimental study of transport properties of porous rock salt

Physics and Chemistry of the Earth ◽

10.1016/s0079-1946(98)00039-1 ◽

1998 ◽

Vol 23 (3) ◽

pp. 367-371 ◽

Cited By ~ 17

Author(s):

E. Spangenberg ◽

U. Spangenberg ◽

C. Heindorf

Keyword(s):

Experimental Study ◽

Transport Properties ◽

Rock Salt ◽

Porous Rock

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Progress in Physical Rock Matrix Characterization: Structure of the Pore Space

MRS Proceedings ◽

10.1557/proc-506-671 ◽

1997 ◽

Vol 506 ◽

Cited By ~ 3

Author(s):

M. Sütari-Kauppi ◽

E.S. Flitsiyan ◽

P. Klobes ◽

K. Meyer ◽

K-H. Hellmuth

Keyword(s):

Image Analysis ◽

Transport Properties ◽

Pore Space ◽

Quantitative Autoradiography ◽

Probe Molecule ◽

Rock Matrix ◽

Porous Rock ◽

Thin Sections ◽

Rock Types ◽

Physical Rock

ABSTRACTQuantitative autoradiography for the investigation of rock matrices has been further developed by use of tritium-labeled polymethylmethacrylate (3H-PMMA), the use of thin sections and image analysis functions allowing correlations of mineralogic-petrographical and analytical or porosity information. The autoradiographic system was studied experimentally and theoretically. The autoradiography could achieve a resolution down to 10 and 20 μm for 3H and 14C, respectively. Possible candidates for intact, low-porous rock standard materials were studied and the measurement of their transport properties discussed. Porosities and diffusivities measured in rock types dominated by very small pores were depending on the probe molecule used. The effect was most pronounced in flint which gave low porosities for MMA, Hg and He and no diffusivities at all for He.

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Spectroscopic Diagnostics of Tokamaks

International Astronomical Union Colloquium ◽

10.1017/s0252921100107638 ◽

1988 ◽

Vol 102 ◽

pp. 165-174

Author(s):

C. de Michelis

Keyword(s):

Transport Properties ◽

Power Losses ◽

Spectroscopic Diagnostics ◽

Important Concern

AbstractImpurities being an important concern in tokamaks, spectroscopy plays a key role in their understanding. Techniques for the evaluation of concentrations, power losses and transport properties are surveyed, and a few developments are outlined.

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Structure and Orientation of As Precipitates in LT-MBE Grown GaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088816 ◽

1991 ◽

Vol 49 ◽

pp. 900-901 ◽

Cited By ~ 1

Author(s):

Alain Claverie ◽

Zuzanna Liliental-Weber

Keyword(s):

Transport Properties ◽

Layer Thickness ◽

Growth Temperature ◽

Low Temperatures ◽

Lattice Parameter ◽

Crystalline Quality ◽

Insulating Properties ◽

Lt Gaas

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

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