Mass Transfer & Porous Media (MTPM) - Andra

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P/<strong>MTPM</strong>/38–Samples cored at 12m were not fractured. The comparison beetween Helium and Nitrogen permeabilitytests clearly demonstrate the importance of Knudsen diffusion. At an 66% equilibrium relativehumidity, the Klikenberg coefficient ranges from 0.5 to 1.5 MPa for Nitrogen tests, and the intrinsicpermeability ranges from 10 -20 m 2 to 5.10 -20 m 2 . The importance of the Knudsen flow regime indicatesthat the flow occurs in small pores at the microscopic level.–Confined permeability tests showed a strong influence of the confining pressure. One test performedon an intact sample brought at hydric equilibrium with a 80% relative humidity showed that the differentialpressure needed for the gaz to penetrate into the sample is higher than 10MPa when confiningpressure is 12MPa. For a sample brougth at hydric equilibrium with a 66% relative humidity, a tresholddifferential pressure of 2.7Mpa is oberved. This treshold is not observed for unconfined permeabilitytests. Further testing at lower relative humidities is in progress.ACKOWLEDGEMENTSThis work has been funded by ANDRA (Agence Nationale pour la gestion des Déchets RAdioactifs)References :Marshall P., Horseman S., Gimmi T., Characterisation of gas transport properties of the Opalinus clay, apotential host rock formation for radioactive waste disposal., 2005,Oil & Gas Technology – Rev. Ifp.Vol 60,pp.121-139.Nelder J.A., Mead R.A., A simplex method for function minimization. The computer Journal 1965, vol 7,pp 308-313.Thomas L. K., Katz D.L., Tek M.R., Threshold phenomena in porous media, 1968, Soc. Petroleum Eng. J.,vol 243, pp 174-183.Page 498INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENT
P/<strong>MTPM</strong>/39CORE 2D V4: A GENERAL PURPOSE CODEFOR GROUNDWATER FLOW, HEATAND SOLUTE TRANSPORT, CHEMICALREACTIONS AND BIOLOGICAL PROCESSESIN POROUS AND FRACTURED MEDIAC. Yang 2 and J. Samper 11. Universidad de A Coruña, Campus de Elviña, 15192 A Coruña, Spain ( jsamper@udc.es )2. Now at Department of Geological Sciences, Indiana University at Bloomington, Indiana. USAINTRODUCTIONUnderstanding natural groundwater quality patterns, quantifying groundwater pollution and assessing theeffects of waste disposal, require modeling tools accounting for water flow, and transport of heat anddissolved species as well as their complex interactions with solid and gasses phases and microbialprocesses. CORE denotes a series of computer codes developed by the Universit of La Coruña which sharethe following main description: COdes for modeling saturated/unsaturated water flow, heat transport andmulti-component REactive solute transport under both local chemical equilibrium and kinetic conditions.CORE uses the sequential iteration approach to solve the coupled hydrological transport processes andhydrochemical reactions. The finite element method is used for spatial discretization, while general finitedifference schemes are used for time discretization. CORE can cope with heterogeneous systems havingirregular internal and external boundaries. The code can handle heterogeneous and anisotropic media in 1,2- and 3-D axysymmetric problems. Both steady-state and transient flow regimes can be simulated.Prescribed head and water flux as well as mixed boundary conditions are included. Both point and arealfluid sources can be specified. In addition, free drainage boundary condition (unit gradient type) is allowedfor variably saturated flow. Solute transport processes included in the code are: advection, moleculardiffusion and mechanical dispersion. Solute transport boundary conditions include: (1) specified solutemass fluxes, (2) specified solute concentrations and (3) solute sources associated to fluid sources. The codecan handle the following types of reactions under the local equilibrium assumption: acid-base, aqueouscomplexation, redox, mineral dissolution/precipitation, gas dissolution/exsolution, ion exchange (based onthe constant charge model) and sorption via surface complexation (using the diffuse double layer model).CORE can take into account any number of aqueous, exchanged and sorbed species, minerals and gases.Heat transport is solved at each time step. Computed temperatures are used for updating equilibriumconstants and the constants for calculating activity coefficients. BIOCORE 2D (Zhang, 2001) is a versionwhich copes with both thermodinamically-controlled abiotic geochemical reactions and subsurfacemicrobial processes in 2-D while INVERSE-CORE (Dai and Samper, 2004). solves the inverse problemof automatic estimation of flow, solute and chemical parameters.RECENT DEVELOPMENTSHere we present CORE 2D V4, the most recent version of CORE 2D which was developed from CORE 2D V2(Samper et al., 2000) and shares the capabilities of codes within the CORE family such as automatic timestepping, kinetic aqueous complexes reactions, and microbial processes in BIOCORE 2D (Samper et al.,2006a) and inverse subroutines of INVERSE-CORE 2D (Dai and Samper, 2004). In addition, CORE 2D V4incorporates the following features: 1) Anisotropic diffusion, to deal with diffusion anisotropy of claymedia (Samper et al. 2006b), 2) Non-linear adsorption isotherms, 3) Evaporation, 4) Isotopes transportcoupled with chemical reactions for the purpose of simulating radionuclide release from a HLW repository,5) Changes in physical properties of porous medium with time due to chemical reactions, 6) Accuratecalculation of mass balances and mass fluxes, 7) Improved SIA and 8) Extending inverse subroutines toestimate flow, transport, chemical and biological parameters.INTERNATIONAL MEETING, SEPTEMBER 17...>...18, 2007, LILLE, FRANCECLAYS IN NATURAL & ENGINEERED BARRIERSFOR RADIOACTIVE WASTE CONFINEMENTPage 499
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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
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P/MTPM/5Oxalate ionsQuartzQuartz +P
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P/MTPM/6borehole was capped with a
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P/MTPM/7Initial state with glass an
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P/MTPM/8The mesh of the elementary
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P/MTPM/9Moreover, using another sam
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P/MTPM/10Figure 1: Horizontal cross
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P/MTPM/11n t (mol)as received8 10 -
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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 62 and 63: P/MTPM/30The presented theory is ex
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 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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Mass Transfer & Porous Media (MTPM) - Andra

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