Introducing interacting diffuse layers in TLM calculations: A reappraisal of the influence of the pore size on the swelling pressure and the osmotic efficiency of compacted bentonites

Gonçalvès, Julio; Rousseau-Gueutin, Pauline; Revil, A.

doi:10.1016/j.jcis.2007.07.023

Cited by 57 publications

(61 citation statements)

References 24 publications

(67 reference statements)

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“…In order to develop an analytical solution, constant parameters are assumed in the following development while, for instance, the diffusion coefficient and e vary with the concentration [see, e.g., Neuzil, 2000;Revil et al, 2005;Gonçalvès et al, 2007]. Consequently, the pressure diffusion equation which has to be solved for an argillaceous porous medium is ), r is the density of the fluid (kg m…”

Section: Mathematical Formulationmentioning

confidence: 99%

A slug test to assess the osmotic and hydraulic properties of argillaceous formations

Gonçalvès

2008

Water Resources Research

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[1] Pulse tests in pressurized chambers represent a very efficient method to estimate the hydrodynamic properties of low-permeability formations. Useful analytical solutions for purely hydraulic pulse test interpretation have been proposed. In the present note an extension of the classical model by Bredehoeft and Papadopulos (1980) is developed for a single hydraulic and/or chemical (osmotic) pulse test involving Laplace transforms. This solution is used to identify graphical variables in an osmotic pulse test record which can be used to estimate the relevant hydrochemical parameters.Citation: Gonçalvès, J. (2008), A slug test to assess the osmotic and hydraulic properties of argillaceous formations, Water Resour.

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Section: Mathematical Formulationmentioning

confidence: 99%

A slug test to assess the osmotic and hydraulic properties of argillaceous formations

Gonçalvès

2008

Water Resources Research

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“…This view is adopted, for example, as the molecular basis for the widely-applied triple-layer model (TLM [3][4][5]), on which the distribution of ions near a charged planar solid surface is calculated under a set of simplifying assumptions that include assigning all ISSCs to a plane at the solid surface (0-plane), all OSSCs to a second plane lying farther into the aqueous phase (β-plane), and all DS species to a region lying beyond a third plane farther out than the β-plane (d-plane) ( Inferences about EDL surface speciation and molecular structure from experimental data on proton and ion adsorption [6,7,8], salt filtration efficiency [9], second harmonic generation [10], electrophoretic mobility [11], or interparticle forces [12] are necessarily sensitive to simplifying EDL model assumptions such as those just described for the TLM [13][14][15][16]. Models of the EDL that approximate liquid water as a uniform dielectric continuum (such as the Poisson-Boltzmann equation [17,18], hypernetted chain theory [19,20], or the primitive model [18,21]) inherently cannot describe surface complexes [17,18].…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of the electrical double layer on smectite surfaces contacting concentrated mixed electrolyte (NaCl–CaCl2) solutions

Bourg

Sposito

2011

Journal of Colloid and Interface Science

254

224

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We report new molecular dynamics results elucidating the structure of the electrical double layer (EDL) on smectite surfaces contacting mixed NaCl-CaCl 2 electrolyte solutions in the range of concentrations relevant to pore waters in geologic repositories for CO 2 or high-level radioactive waste (0.34 to 1.83 mol c dm -3 ). Our results confirm the existence of three distinct ion adsorption planes (0-, β-, and d-planes), often assumed in EDL models, but with two important qualifications: (1) the location of the β-and dplanes are independent of ionic strength or ion type and (2) "indifferent electrolyte" ions can occupy all three planes. Charge inversion occurred in the diffuse ion swarm because of the affinity of the clay surface for CaCl + ion pairs. Therefore, at concentrations ≥ 0.34 mol c dm -3 , properties arising from long-range electrostatics at interfaces (electrophoresis, electro-osmosis, co-ion exclusion, colloidal aggregation) will not be correctly predicted by most EDL models. Co-ion exclusion, typically neglected by surface speciation models, balanced a large part of the clay mineral structural charge in the more concentrated solutions. Water molecules and ions diffused relatively rapidly even in the first statistical water monolayer, contradicting reports of rigid "ice-like" structures for water on clay mineral surfaces.

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“…They allow the calculation of the electrical potential distribution as a function of the distance to the charged surfaces. Among these models, electrical triple layer models (TLM) describe the distribution of the ions within the porosity using three domains [see, e.g., Davis and Leckie, 1978;Hiemstra and Van Riemsdijk, 1996;Leroy and Revil, 2004;Gonçalvès et al, 2007]: (1) the Stern layer is a compact layer formed by ions that are directly bound to the surface (covalent or ionic bonds) plus strongly attracted hydrated ions [Sposito et al, 1999]; (2) the diffuse layer, where the ions are attracted by the surface but more dispersed, which is thus considered as part of the solution; and (3) the last layer, when it exists, which is the free electrolyte or equilibrium solution where the electrical field is null and where the electroneutrality is achieved by the ionic balance. These models, introducing a compact Stern layer, are known as Stern-Grahamme models.…”

Section: Introductionmentioning

confidence: 99%

What is the significance of pore pressure in a saturated shale layer?

Gonçalvès

Rousseau-Gueutin

Marsily

et al. 2010

Water Resources Research

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International audienceElectrostatic interactions, associated with negatively charged surfaces of clay minerals, produce a so-called "disjoining pressure" when diffuse layers overlap, i.e., at low porosity. Disjoining pressure is the pressure difference between the water in the clay pore space and that in a bulk solution at the same depth. Another widely used concept in clay-rocks is the "swelling pressure." It corresponds in fact to the macroscopic average of the disjoining pressure. This study proposes to determine the value of the swelling pressure of a natural material by a simple volume-averaging approach of the disjoining pressure, calculated for each clay mineral present in the material. The swelling pressure, which is dependent on the salinity of the pore fluid, is introduced into a hydrochemomechanical coupling, yielding a more general pressure diffusion equation. The results are compared to swelling pressure measurements for natural shale samples. The implications of this swelling pressure for water pressure measurements in natural formations are also discussed

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Introducing interacting diffuse layers in TLM calculations: A reappraisal of the influence of the pore size on the swelling pressure and the osmotic efficiency of compacted bentonites

Cited by 57 publications

References 24 publications

A slug test to assess the osmotic and hydraulic properties of argillaceous formations

A slug test to assess the osmotic and hydraulic properties of argillaceous formations

Molecular dynamics simulations of the electrical double layer on smectite surfaces contacting concentrated mixed electrolyte (NaCl–CaCl2) solutions

What is the significance of pore pressure in a saturated shale layer?

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