Transport properties and microstructural characteristics of a thermally cracked mylonite |
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| Authors: | M Le Ravalec M Darot T Reuschlé Y Guéguen |
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| Institution: | (1) Géosciences Rennes, Université Rennes I, Bâtiment 15, Campus Beaulieu, Avenue Général Leclerc, 35042 Rennes Cedex, France;(2) C.N.R.S. URA 1358, Laboratoire de Physique des Matériaux, E.O.P.G.S., 5 rue René Descartes, 67084 Strasbourg Cedex, France |
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| Abstract: | An experimental study was carried out on a granitic mylonite (La Bresse, France) to analyze the influence of pore microstructure on transport properties. Different crack networks were obtained by a controlled thermal treatment. Microstructures were analyzed by means of gas adsorption and mercury porosimetry. Transport properties have been investigated by measuring gas permeability and electrical conductivity. The dependence of permeability on confining pressure shows an exponential decrease, characteristic of a porosity made of cracks. Correlations between measured parameters have been analyzed by comparing them with relations deduced from theoretical models. Linking the formation factor to the porosity leads to a rather low tortuosity value (about 2.4), characterizing a medium with a well connected porosity. Correlation between permeabilityk and formation factorF leads to a power-law relationk  F
–n
wheren 2.9, which is consistent with a crack model describing the behavior of the thermally treated rock. |
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| Keywords: | Transport properties pore microstructure porosity |
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