Presentacin de PowerPoint

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Main fields of applications

• Spatial scale
• Lab experiments
• In situ experiments
• Regional aquifers/aquitards
• Time scales
• Short term lab experiments
• Medium term in situ experiments (10 a)
• Long-term performance assessment calculations
  in near field of a HLW repository

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Main fields of applications

• Reactive transport in fracture zones
• Coupled THBC (m) models
• Long-term performance assessment
• Reactive and microbial models
• Parameter estimation inverse models
• Numerical aspects
• More recent work
• RT and spatial heterogeneity
• Dual continua
• Combining numerical and analytical methods

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Main fields of applications

• Reactive transport in fracture zones
• Redox Zone and REX experiments (Äspö)
• Need to account for microbial processes
• Evaluation of dissolved oxygen consumption
• In bentonite
• During open repository conditions
• Glaciation episode (with microbial processes)

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CERBERUS experiment (Mol)

• Performed on Boom clay Mol, Belgium
• In situ heat and radiation source
• In situ chemical monitoring
• 1D axissymmetric THC

(Zhang et al., Appl. Geochem, 2007)
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Ventilation experiment (Mont Terri)

• Performed on Opalinus Clay (OC) Mont Terri
• Micro-tunnel of 1.3 m diameter and 10 m long. It
  was sealed off
• Several de-saturation and resaturation phases
• On line monitoring of hydraulic and mechanical
  data
• Chemical data at the end of S-R phases

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Multiphase flow and RT model

• Ventilation experiment
• Multiphase flow
• water gas (vapor and dry air)
• Multicomponent reactive solute transport
• Transport Advection, molecular diffusion
  dispersion
• Chemistry aqueous complexation, acid-base,
  redox, mineral dissolution/precipitation, gas
  dissolution/ex-solution cation exchange
• Minerals pyrite, Fe(OH)3, siderite, calcite,
  dolomite, gypsum, quartz

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Multiphase flow and RT model

• Numerical model
• 2D-Axial symmetry
• Rectangular finite element mesh 204 nodes 101
  elements

porosity 0.1605, hydraulic conductivity
2.010-13 m/s, Vapor tortouosity 0.8, relative
permeability Kr Sr4, longitudinal dispersivity
0.12 m, Pore water diffusion coefficient
210-10 m2/s
Calculations performed with our domestic THMC
code INVERSE-FADES-CORE2D
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Hydrodynamic model results
Liquid pressure
Mesurements of piezometers below 100 kPa may be
unreliable
Vapor outflow
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Hydrodynamic model results
Relative humidity
Model overestimates RH after de-saturation phase
probably due to uncertainties on the turbulence
factor used to calculate vapor outflow
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Chemical results pyrite

• Pyrite is oxidized due to oxygen in-diffusion
  when tunnel is ventilated and rock de-saturates

FeS2(s) H2O 3.5 O2(aq) ? 2 SO42 Fe2 2 H
Although rock resaturated from phase 6 to 8,
pyrite continued to oxidize due to O2
in-diffusion
Pyrite
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Chemical results ferrihydrite calcite

• Pyrite oxidation induces
• Ferrihydrite precipitation
• Calcite dissolution (which buffers pH)

2.5 H2O 0.25 O2(aq) Fe2 ? Fe (OH)3(s) 2 H
CaCO3(s) H ? Ca2 HCO3-
Calcite
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Chemical results gypsum dolomite

• Dissolved Ca HCO3 released by calcite induce
  gypsum and dolomite precipitation

Ca2 SO42- 2 H2O ? CaSO42H2O
Mg2 Ca2 2 HCO3 ? CaMg(CO3)2(s) 2 H
Dolomite
Gypsum
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Chemical results Cl exclusion
Time evolution of Cl in clay at 2 cm from tunnel
surface
With anion exclusion (accessible porosity 54
of total porosity) Consistent with independent
estimates
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Chemical results Cl exclusion
Cl SO4 in boreholes after resaturation (phase 8)
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Model testing with inferred chemical data
HCO3
pH
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HC coupling Changes in porosity
Changes in porosity caused by oxidation and
mineral dissolution/precipitation are very small.
lt 2 although initially reaches 5 near rock
surface
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HLW performance assessment

• Clay/concrete/bentonite long-term gechemical
  evolution in a HLW repository in clay (NFPRO)
• Canister/bentonite/granite long-term gechemical
  evolution in a HLW repository in granite (NFPRO)

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Modeling long-term (1Ma) geochemical evolution
and bentonite-concrete-clay interactions in a HLW
repository in clay
Na
pH plume penetrates only 1 m into clay formation
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• Bentonite, concrete clay porosities decrease,
  but no clogging is predicted

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Main fields of applications

• Multiphase and coupled TH(m)C models
• Heat released by radiation during thermal phase
• Engineered barriers FEBEX experiment
• CERBERUS experiment
• Effect of ventilation VE experiment
• Meet the needs of process-level performance
  assessment models
• Interactions of engineered barriers
• Canister/bentonite/granite
• Concrete/bentonite/clay

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Main fields of applications

• Coupled reactive and microbial models
• Evaluate effect of microbes on redox potential
• Redox Zone and REX experiments at Äspö
• Role of SRB in sulfate reduction in Boom clay
• Reactor denitrification processes
• Inverse problem for reactive and microbial
  transport
• Combine hydrodynamic and chemical data
• Trial error vs automatic estimation
• Evaluate parameter uncertainties

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Most recent applications

• Reactive transport for heterogeneous systems
• Combining numerical and analytical solutions
• Reactive transport in dual (multiple?) continua
• Clear need for clays formations and bentonites
• Approaches overlapping or non-overlapping
  continua
• Challenges
• How to get parameters
• Differences in chemical systems

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Most recent applications

• Acid mine drainage and pit lakes
• Pyrite oxidation is the source of acidity
• During lake creation
• Ferrihydrite (HFO) precipitation
• Surface complexation on HFO surfaces
• Coupling CORE with a dynamic lake model

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Most recent applications

• Acid mine drainage and pit lakes
• Pyrite oxidation is the source of acidity
• During lake creation
• Ferrihydrite (HFO) precipitation
• Surface complexation on HFO surfaces
• Coupling CORE with a dynamic lake model

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Time-depth plot of lake pH
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Time-depth plot of lake sulfate
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Most recent applications

• RT models are needed to properly interpret
  classical tracer experiments
• Anion exclusion Cl experiments
• Changes in chemistry during long-term diffusion
  experiments

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Developments in numerical methods

• Sequential approaches
• Non iterative SNIA
• Fully iterative SIA
• Predictor-corrector
• Partly iterative SPIA
• Subgrid scale stabilization algorithms for
  reactive transport
• Works nicely for extremely advective problems
  (see Yang and Samper, 2008, Ad. Wat. Res.)

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Developments in numerical methods

• Solving chemical equations
• Working with increments of log c
• Modified Newton-Raphson
• Neglecting derivatives of activity coefficients
• Implementing Armijo algorithm
• Using Neural networks as a pre-conditioner of
  Newton-Raphson
• Algorithms for automatic time stepping for stiff
  problems

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How much should we trust models?
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Publications (i)

• Changbing Yang, Javier Samper, Jorge Molinero and
  Mercedes Bonilla, 2007, Modelling geochemical and
  microbial consumption , J. Cont. Hydrol.
• Samper, J. C. Yang A semi-analytical solution
  for linearized multicomponent cation exchange
  reactive transport in groundwater, In Transport
  in Porous Media, DOI 10.1007/s11242-006-9065-4,
  2006.
• J. Samper, G. Zhang, and L. Montenegro 2006,
  Coupled microbial and geochemical reactive
  transport models, Journal of Iberian Geology, Vol
  32(2), 215-231.
• J.M. Galíndez, J. Molinero, J. Samper and C.B
  Yang, Simulating concrete degradation processes
  by reactive transport models, J. Phys. IV France,
  136 (2006) 177-188.
• Samper, J., C. Yang, A. Naves, A Yllera, A.
  Hernández, J. Molinero, J. M. Soler, P. Hernán,
  J.C. Mayor and J. Astudillo, A fully 3-D
  anisotropic model of DI-B, Physics and Chemistry
  of the Earth, Vol. 31, 531-540. 2006.
• Samper, J., Z. Dai, J., Molinero, M.
  García-Gutiérrez, T. Missana y M. Mingarro,
  Inverse modeling of tracer experiments in FEBEX
  compacted Ca-bentonite, Physics and Chemistry of
  the Earth, Vol. 31, 640-648, 2006.
• Z. Dai, J. Samper and R. Ritzi, 2006,
  Identifying geochemical processes by inverse
  modeling of multicomponent reactive transport in
  Aquia aquifer, Geosphere, 2006, Vol. 4, Nº 4,
  210219.
• J. Samper and C. Yang, 2006, Stochastic Analysis
  of Transport and Multicomponent Competitive
  Cation Exchange, Geosphere, April, Vol. 2,
  102-112, 2006.
• Dai Z. and J. Samper, 2006, Inverse modeling of
  water flow and multicomponent reactive transport
  in coastal aquifer systems. J. of Hydrol. Vol.
  327, Issues 3-4, 447-461.
• Molinero J and J. Samper, Modeling of reactive
  solute transport in fracture zones of granitic
  bedrocks, Journal of Contaminant Hydrology 82
  293 318. 2006.
• Yllera A., Hernández A., Mingarro M., Quejido A.,
  Sedano L. A., Soler J. M., Samper J., Molinero
  J., Barcala J. M., Martín P. L., Fernández M.,
  Wersin P., Rivas P., Hernán P. (2004) DI-B
  Experiment Planning, Design and Performance of
  an In Situ Diffusion Experiment. Applied Clay
  Science 26, 181-196. . (Revista del SCI)
• Molinero Huguet, J. Samper, J. G. Zhang y C.
  Yang. Biogeochemical reactive transport model of
  the redox zone experiment of the Äspö hard rock
  laboratory in Sweden, En Nuclear Technology, Vol
  148, pp. 151-165, 2004.
• J. Molinero y J. Samper, Groundwater Flow and
  Solute Transport in Fracture Zones An Improved
  Model for a Large-Scale Field Experiment at Äspö,
  J. Hydr. Res. Vol. 42, 2004, Extra Issue,
  157-172.

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Publications (ii)

• Yang, C., S. Jones and J. Samper, 2007, Numerical
  modelling of the development of a preferentially
  lached layer on feldspar surfaces, Applied
  Geochemistry (submitted)
• Samper, J., S. Dewonck, L. Zheng, Q. Yang, and A.
  Naves, 2008, Normalized sensitivities and
  parameter identifiability of in situ DIR
  diffusion experiments on Callovo-Oxfordian clay
  at Bure site, Physics and Chemistry of the Earth
  (submitted).
• Samper, J., L. Zheng, and L. Montenegro 2008,
  Inverse hydrochemical models of aqueous extract
  experiments, Physics and Chemistry of the Earth
  (submitted).
• Yang, C, J. Samper and J. Molinero, 2008, Inverse
  microbial and geochemical reactive transport
  models in porous media, Physics and Chemistry of
  the Earth, (submitted).
• Yang, C., J. Samper and L. Montenegro, 2008,
  CORE2D V4 A Code for water flow, heat and solute
  transport, geochemical reactions, and microbial
  processes, Physics and Chemistry of the Earth,
  (submitted).
• Zheng, L. J. Samper, 2008, Coupled THMC model
  of FEBEX mock-up test, Physics and Chemistry of
  the Earth, (submitted).
• Samper, J., C. Lu, L. Montenegro, 2008, Coupled
  hydrogeochemical calculations of the interactions
  of corrosion products and bentonite, Physics and
  Chemistry of the Earth, (submitted).
• Zheng, L., J. Samper, L. Montenegro J.C.
  Mayor, 2008, Flow and reactive transport model of
  a ventilation experiment in opallinus clay,
  Physics and Chemistry of the Earth, (submitted).
• Samper J., C. Lu, and L. Montenegro, 2008,
  Reactive transport model of interactions of
  corrosion products and bentonite, Physics and
  Chemistry of the Earth, (submitted).
• Yang C. y J. Samper. 2008, A Subgrid-Scale
  Stabilized Finite Element Method for
  Multicomponent Reactive Transport through Porous
  Media, Advances in Water Resources, (in press).
• Samper, L. Zheng, A.M. Fernández and L.
  Montenegro, 2008, Inverse modeling of
  multicomponent reactive transport through single
  and dual porosity media, J Cont Hydrol (in
  review).
• Samper J., L. Zheng, L. Montenegro, A.M.
  Fernández, P. Rivas, 2007, Testing coupled
  thermo-hydro-chemical models of compacted
  bentonite after dismantling the FEBEX in situ
  test, Applied Geochemistry (in press).
• Zhang G, J. Samper L. Montenegro, 2007, Coupled
  thermo-hydro-bio-geochemical reactive transport
  model of the CERBERUS heating and radiation
  experiment in Boom clay, Applied Geochemistry (in
  press).