Mass Transfer & Porous Media (MTPM) - Andra

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P/<strong>MTPM</strong>/30The presented theory is exemplified by a modeling of two gas migration experiments usingCode_Bright, a 2-phase FEM-code for mass, energy and momentum balance in porous media( CIMNE, 2000). Quantitative agreement with experiment is achieved when adopting a Gas EntryValue (GEV) retention curve, i.e. a constitutive equation relating liquid saturation, , and suction withthe property thatSl ()= s 1 for all s ≤ P s .An example of results from such a modeling is presented in Figure 1.Modeling of BGS experiment 1997Gas Pressure (MPa)1716151413124.5E-084.0E-083.5E-083.0E-082.5E-082.0E-081.5E-081.0E-085.0E-090.0E+000 5 10 15 20 25 30Time (days)Flow Rate (m 3 /s) at STPPg, model (GEV = 13.9 MPa)Pg, AnalyticalOutflow, ExperimentalPg, ExperimentalOutflow, model (GEV = 13.9 Mpa)Figure 1: Results of modeling of gas migration experiments by Horseman and Harrington, 1997. Abreakthrough event occurs around day 7, and the gas inflow is turned off at day 14. The Code_Brightmodel, based on the presented theory, successfully captures the breakthrough, and the subsequent flow rateand pressure level evolution.ReferencesBucher F. and Müller-Vonmoos M. (1989) Bentonite as a Containment Barrier for the Disposal of HighlyRadioactive Wastes, Applied Clay Science, 4, 157-177CIMNE, (2000). CODE_BRIGHT. A 3-D program for thermo-hydro-mechanical analysis in geologicalmedia. Departamento de Ingeneria del Terreno; Cartgrafica y Geofisica, UPC, Barcelona, SpainHorseman, S.T. and Harrington, J.F. (1997). Study of gas migration in MX-80 buffer bentonite. BGSinternal report WE/97/7 to SKBKarnland O., Muurinen A. and Karlsson F. (2005) Bentonite swelling pressure in NaCl solutions –Experimentally determined data and model calculations in Advances in Understanding Engineered ClayBarriers – Alonso & Ledesma (eds.), Taylor & Francis Group, LondonPage 482INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/<strong>MTPM</strong>/31EVALUATING THE APPLICATIONOF ARCHIE’S LAWFOR ARGILLACEOUS ROCKSP. Blum 1 , M. Scheunemann 1 , L. Van Loon 2 , D. Coelho 3 , N. Maes 4 , P. Grathwohl 11. University of Tübingen, Center for Applied Geosciences (ZAG), Sigwartstr. 10, 72076 Tübingen,Germany, (philipp.blum@uni-tuebingen.de)2. Paul Scherrer Institut (PSI), CH-5232 Villingen, Switzerland, (luc.vanloon@psi.ch)3. ANDRA, 92298 Châtenay-Malabry, France, (daniel.coelho@andra.fr)4 . SCK-CEN, Boeretang 200, B-2400 Mol, Belgium, (nmaes@sckcen.be)INTRODUCTIONDiffusion is an important transport process in geological systems. Hence, for the safety assessment ofpotential radioactive waste repositories that might be build in such geological systems, effective diffusioncoefficients of various species need to be known. The effective diffusion coefficients strongly depend onporosity. Moreover, previous studies could demonstrate that the effective diffusion coefficients can beestimated using Archie’s law:D e = D aq . ε m (1)where D e is the effective diffusion coefficient, D aq is the diffusion coefficient in bulk water, ε is thetransport porosity and m represents an empirical constant depending on the type of porous medium. Boving& Grathwohl (2001) studied the diffusion of iodide (I - ) in different limestone and sandstone rocks. Theexponent m that fitted the data the best was approximately 2.2. Another study, which focused on chalk,showed that the data for various inorganic and organic compounds resulted in an exponent of around 2.4(Blum, 2000). A few studies also considered the application of Archie’s law for diffusion in argillaceousrocks. Grathwohl (1998) studied the diffusion of tetrachloroethene (TCE) in natural clays (Figure 1). Agood fit with Archie’s law was obtained using the transport-through porosity.0.250.2km5scsbavla1abenD’ = ε 3/2D’ = ε 2D’ = ε 5/20.250.2D’ = ε 3/2D’ = ε 2D’ = ε 5/2D’ = D e /D aq0.150.10.05D’ = D e /D aq0.150.10.05km5scsbavla1aben(a)00.2 0.3 0.4 0.5 0.6Porosity ( ε )0.2 0.3 0.4 0.5 0.6Transport-Through Porosity ( ε t )Figure 1: (a) Normalized diffusion coefficient (D’) of TCE versus overall porosity. (b) Normalizeddiffusion coefficient (D’) of TCE versus corrected porosity based on water adsorbed onto dry samples ata relative humidity of 98.8 %. The lines represent Archie’s law. km5: Triassic clay (Knollenmergel); scs:silty-clayey soil; bav: Jurassic clays (Opalinus Clay, Dogger α ); la1: Jurassic clay (Lias α 1); aben:activated bentonite.0(b)INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 483
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Poster [MTPM]Mass Transfer & Porous
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P/MTPM/1The free energy cost of for
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P/MTPM/3DIFFUSION OF IONS IN UNSATU
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P/MTPM/4POROUS MEDIA CHARACTERIZATI
Page 12 and 13: P/MTPM/5Oxalate ionsQuartzQuartz +P
Page 14 and 15: P/MTPM/6borehole was capped with a
Page 16 and 17: P/MTPM/7Initial state with glass an
Page 18 and 19: P/MTPM/8The mesh of the elementary
Page 20 and 21: P/MTPM/9Moreover, using another sam
Page 22 and 23: P/MTPM/10Figure 1: Horizontal cross
Page 24 and 25: P/MTPM/11n t (mol)as received8 10 -
Page 26 and 27: P/MTPM/1210,9Degree of saturation (
Page 28 and 29: P/MTPM/13RESULTSFirst, we estimated
Page 30 and 31: P/MTPM/142.5Energy (M eV)1.6 1.7 1.
Page 32 and 33: P/MTPM/15C/Co10.90.80.70.60.50.40.3
Page 34 and 35: P/MTPM/16ModelIrmayvG-M1vG-M2vG-M3T
Page 36 and 37: P/MTPM/17Figure 1: Experimental HTO
Page 38 and 39: P/MTPM/18Diffusion experiments were
Page 40 and 41: P/MTPM/19Figure 1: Used mesh for co
Page 42 and 43: P/MTPM/201.81.61.41.2upstream compa
Page 44 and 45: P/MTPM/21490Pressure [bar]0 10 20 3
Page 46 and 47: 134P/MTPM/22through-diffusion exper
Page 48 and 49: P/MTPM/23HA (µg/g)3002001000(a):pH
Page 50 and 51: P/MTPM/24through each sample. The p
Page 52 and 53: P/MTPM/25FIRST RESULTSPreliminary c
Page 54 and 55: P/MTPM/26heterogeneous distribution
Page 56 and 57: P/MTPM/27Relative concentration (C-
Page 58 and 59: P/MTPM/280.75m0.25mTable 1: Cross s
Page 60 and 61: P/MTPM/29Figure 1: A. Scheme of the
Page 64 and 65: P/MTPM/31Furthermore, Van Loon et a
Page 66 and 67: P/MTPM/32RESULTSResults show that,
Page 68 and 69: P/MTPM/33Clay modellingPore size di
Page 70 and 71: P/MTPM/341.60E-11f H2-d total (kg.m
Page 72 and 73: P/MTPM/350.50η R ()0.400.300.200.1
Page 74 and 75: P/MTPM/36200Bq/g1801601401201008060
Page 76 and 77: P/MTPM/37Argilite (ionic strength 0
Page 78 and 79: P/MTPM/38-Samples cored at 12m were
Page 80 and 81: P/MTPM/39APPLICATIONSCORE 2D has be
Page 82 and 83: P/MTPM/40Figure 1: Sketch drawing o
Page 84 and 85: P/MTPM/41Figure 1: Thermal conducti
Page 86 and 87: P/MTPM/42Figure 2: Model of pore st
Page 88 and 89: P/MTPM/43The available data are con
Page 90 and 91: P/MTPM/44Figure 1: Spatial extensio
Page 92 and 93: P/MTPM/45Relative concentration / (
Page 94 and 95: P/MTPM/46Figure 2: Swelling pressur
Page 96 and 97: P/MTPM/47then used in the transport
Page 98: P/MTPM/4820181614121086Gas pressure
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