P/<strong>MTPM</strong>/41Figure 1: Thermal conductivity mapping of samples showing a diagenetic control. Upper part, sectionperpendicular to the bedding (dashed line); yellow to red : calcite cement. Lower part, section parallel tobedding; some variation of the thermal conductivity is observed, between 1.2 (in blue) and 2 W.m -1 .K -1 (ingreen). Using both sections an anisotropy tensor could be reconstructed with a lower value perpendicularto the K 1 axis of the magnetic anisotropy.Figure 2: TC profiles obtained from thesame core drilled at the wall of theunderground laboratory. The low TCzone (between 0.5 and 1 W.m -1 .K -1 ) atthe beginning of profile 1 cor-respondsto the high porosity of a damaged zone.At the end of profile 2 the high TC valueis due to pyrite grains and the low TCvalues correspond to the high porosityalteration zones sur-rounding the grainsof pyrite.ReferencesEsteban, L., Géraud, Y. and Bouchez, J.L., 2006. Pore network connectivity in Jurassic argillitespecimens from eastern Paris Basin (France). J. Physics & Chemistry Earth , doi : 10.1016/j.pce.2005.11.001 .Esteban, L., Géraud, Y. and Bouchez, J.L., 2006. Pore network connectivity in low permeabilitysediments from magnetic fabric data and oriented mercury injections. Geophysical ResearchLetters, L18311, doi :10.1029/2006GL026908 .Popov, Y.A., Pribnow, D.F.C., Sass, J.H., Williams, C.F. and Burkhardt, H., 1999. Characterization of rockthermal conductivity by high-resolution optical scanning. Geothermics, 28: 253-276.Page 504INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/<strong>MTPM</strong>/42POROSITY NETWORK GEOMETRYAND INFERRED PERMEABITYOF THE CALLOVO-OXFORDIAN ARGILITESFROM MAGNETIC FABRICAND ORIENTED MERCURY INJECTIONSY. Géraud 1 , L. Esteban 1, 2, 3, 4 , J-L Bouchez 2 , A. Trouiller 31. Institut de physique du globe de Strasbourg, UMR 7516, Université Louis Pasteur-CNRS, 1 rueBlessig, F-67089 Strasbourg cedex ( ygeraud@illite.u-strasbg.fr )2. Univ. Toulouse, 14 Ave E. Belin, 31 400-Toulouse and GdR CNRS FORPRObouchez@lmtg.obs-mip.fr3. <strong>Andra</strong>, Parc de la Croix Blanche, 1-7 rue J. Monnet, 32290-Châtenay-Malabry(alain.trouiller@andra.fr)4. Now at Geological Survey of Canada-Pacific, 9860 West Saanich Road, Sidney, B.C., Canada,V8L 4B2 (lesteban@nrcan.gc.ca)INTRODUCTIONThe Jurassic in age, ~ 130 m thick, gray-coloured and homogeneous argillites that host the <strong>Andra</strong>laboratory, are a mix of clay minerals (~ 50%), carbonates (~ 25%) and silts (~ 25%). These argillites havebeen collected at depth (~ 490 m) by <strong>Andra</strong>. From a palaeo-climatological point of view, these argiliteswere deposited during a cold event that lasted ~ 4 Ma within a globally warm period marked by thecarbonate platforms at the base and top of the argillitic formation. In the aim to investigate transferproperties of the material, specimens of the three main lithologies (silty, carbonate and clayey materials)are submitted to a set of combined analyses using magnetic anisotropy axis determination, mercuryinjection and ferro-fluid saturation. These data are used in a numerical model to infer permeability.PORE STRUCTUREThe preliminary magnetic anisotropy measurements point out a specific orientation of the main magneticaxis depending on the lithology and are strongly controlled by the mineral fabric (Figure 1). Along theFigure 1: Sructure parameter obtained by ASMand mercury injection. K1, K2, K3 are mainmagnetic axis (see Bouchez et al. this volume)used for mercury injection (right). Left, ASMorientation after ferro-fluid injection for increasingpressure ( 4, 8, 14 and 70MPa), the initialorientation is supported by mineral orientation inblack, (Esteban et al., 2006a, .Esteban et al., 2007)INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 505