Eric C. Gaucher

Lavoisier H2 Geoconsult

Fluid/rock interaction represents a major process in the formation of calcitic or aragonitic travertine and tufa (CATT). In most cases, CATT is associated to limestone dissolution somewhere along the hydrogeological pathway. However, a wide array of other substratum (basalts, rhyolites, carbonatites, ultramafics, granites, dolomites, evaporites) ca...

Until the end of the 1990s, deep geological clay formations had no direct industrial applications and little research had been conducted to characterize the chemistry of pore-water in indurated clay-rocks. The emergence of the concept of radioactive waste disposal in clay-rock formations led to a research boom in this area. Chemical characterizatio...

Characterization of dissolved CO2 and alkane gas in clayrocks may help assessing the confinement properties of geological barriers considered as potential host rocks for a deep geological disposal as well as for caprocks of gas storages.A monitoring of alkanes with CO2, combined with carbon isotopes was performed on core samples coming from Undergr...

A set of models for estimating the enthalpy of formation, the entropy, the heat capacity and the volume of dehydrated phyllosilicates is presented. The model for entropy and heat capacity estimation is essentially based on a method of decomposition into polyhedral units, similar to that published by Holland (1989). The model for predicting the enth...

The Scandinavian Alum Shale Formation may contain significant gas resources and the play is currently under exploration in Denmark. However, only a few wells are available for analysis, and data on the unit are limited. We here present a methodology and data acquisition workflow defining rock types based on old exploration and scientific wells that...

The use of the subsurface for CO2 storage, geo- thermal energy generation, and nuclear waste disposal will greatly increase the interaction between clay(stone) and concrete. The development of models describing the mineralogical transformations at this interface is complicated, because contrasting geochemical conditions (Eh, pH, solution compositio...

Calcitic or aragonitic travertine and tufa deposits (CATT) are frequently associated to former limestone dissolution in epigean or hypogean hydrogeological reservoirs. However, a large variety of other rocks can also occur as substratum and potential source of elements building these continental carbonates. In modern and recent environments, many s...

Precise hydrogeochemical modeling of early diagenesis is a key in the reconstruction of sedimentary basin models. This determines the mineralogical evolution of the sediment and consequently the porosity of the rock. During early diagenesis also part of the initial organic matter is converted into biogenic gas: CH4 CO2, and H2S. These processes are...

https://www.globalccsinstitute.com/resources/publications-reports-research/carbon-capture-and-storage-the-lacq-pilot-project-and-injection-period-2006-2013/

When capturing CO 2 , the collected gas mixture can vary considerably both qualitatively and quantitatively, based on the CO 2 origin, the capture process and the industrial sector. Co-injected with CO 2 , these impurities might be an issue in case of leakage but may also impact the subsurface storage. Operators of the whole CCS chain are therefore...

Knowledge of the pore water chemistry in clayrock formations plays an important role in determining radionuclide chemical speciation and migration in the context of nuclear waste disposal. Among the different in situ and ex situ techniques for pore water sampling in clay sediments and soils, the squeezing technique dates back 115 years. Although di...

During the last decade, numerous studies have focused on long-term predictive reactive transport modelling of cement/clay interactions. These simulations have been performed using modelling strategies of growing complexity, e.g. (i) taking more minerals into account, (ii) considering the effect of dissolution/precipitation kinetics versus thermodyn...

In the context of the deep waste disposal, we have investigated the respective stabilities of two iron-bearing clay minerals: berthierine ISGS from Illinois [USA; (Al0.975FeIII0.182FeII1.422Mg0.157Li0.035Mn0.002)(Si1.332Al0.668)O-5(OH)(4)] and chlorite CCa-2 from Flagstaff Hill, California [USA; (Si2.633Al1.367)(Al1.116FeIII0.215Mg2.952FeII1.712Mn0...

Argillaceous rocks are considered to be a suitable geological barrier for the long-term containment of wastes. Their efficiency at retarding contaminant migration is assessed using reactive-transport experiments and modeling, the latter requiring a sound understanding of pore-water chemistry. The building of a pore-water model, which is mandatory f...

This article presents the main outputs from the multidisciplinary Carmex project (2009–2012), which was concerned with the possibility of applying ex situ mineral carbonation concepts to mafic/ultramafic mining wastes. Focus points of the project included (i) matching significant and accessible mining wastes to large CO2 emitters through a dedicate...

In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistr...

The stability of clay minerals is an important factor in assessing the durability of containment barriers for deep waste storage. In that context, the complete thermodynamic data set of three 2:1 ferro-magnesian clay minerals have been determined at 1 bar and from 2 to 520 K, using calorimetric methods. The studied clay samples were, respectively,...

Understanding the behavior of a clay mineral-rich rock submitted to different physical-chemical perturbations is important for assessing the safety of nuclear waste disposal facilities in the corresponding geological formations. In this work we studied the effect of rock desaturation on the CO 2 partial pressure signature of the Callovo-Oxfordian a...

Cementitious materials will be widely used in French concept of radioactive waste repositories. During their degradation over time, in contact with geological pore water, they will release hyper-alkaline fluids rich in calcium and alkaline cations. This chemical gradient likely to develop at the cement/clay interfaces will induce geochemical transf...

Introduction A repository of high-level nuclear wastes in the Callovo-Oxfordian (COx) clay rock will lead to a temporary increase in temperature locally around the disposal cells, up to about 80°C. Thermally induced modifications of the pore-water chemistry of the clay rock must be assessed since the pore water chemistry can affect the rates of cor...

The thermodynamic properties of clay minerals, which control the stability of these minerals in solution, are still a matter of debate in spite of recent advances (Gailhanou et al., submitted). This is especially the case for the minerals that may structurally include trace elements and potential radionuclides such like Ni, Cd, Co, Cr, Mn, Pb, ......

The thermodynamic properties of three aluminous 2:1 clay minerals were acquired at 1.013 bars and at temperatures between 5 and 500 K using various calorimetric methods. Calorimetric measurements were performed on hydrated and dehydrated <2 mu m clay fractions of smectite MX-80 (Wyoming), illite IMt-2 (Silver Hill) and beidellite SBId-1 (Black Jack...

For safety evaluation of hazardous waste repositories in clay-rocks, a thorough assessment of porewater chemistry and water-rock interactions is required. However, this objective is a challenging task due to the low hydraulic conductivity and water content of such rocks, which subsequently renders porewater sampling difficult (without inducing pert...

In-situ sampling was performed in the Andra Meuse/Haute Marne (France) Underground Research Laboratory (URL) allowing the study of two cement based materials/claystone interfaces that have undergone 4 to 5 years of interaction. The first interface concerned a shotcrete that was sprayed on the wall of an access drift at the laboratory level and the...

The safety of the future CO2 geological storage is largely dependent on the integrity of existing surrounding wells. Well integrity is of major concern in confinement sites where the number of abandoned wells is particularly high, such as it often occurs in depleted gas and/or oil fields. The degradation of the cement filling of these wells is a ke...

An initial geochemical characterization of clayrocks is needed in order to evaluate their feasibility for use as caprocks or host formations for greenhouse gas storage or nuclear waste disposal facilities, respectively. In this context, a method was developed for the measurement of CO2 partial pressure in clayrock pore water. The PCO2 was systemati...

Geological storage of CO2 in unmineable coal seams could be a very interesting option in the sustainable management of coal basins. However, the various chemical and physical parameters that determine the success or failure of this type of operation need to be clarified. The CHARCO project aims at developing methods and analysis techniques in order...

The effect of pH and Gibbs energy on the dissolution rate of a synthetic Na-montmorillonite was investigated by means of flow-through experiments at 25 and 80 degrees C at pH of 7 and 9. The dissolution reaction took place stoichiometrically at 80 degrees C, whereas at 25 degrees C preferential release of Mg over Si and Al was observed. The TEM-EDX...

CO2 injection in unmineable coal seams could be one interesting option for both storage and methane recovery processes. The objective of this study is to compare and model pure gas sorption isotherms (CO2 and CH4) for well-characterised coals of different maturities to determine the most suitable coal for CO2 storage. Carbon dioxide and methane ads...

This study characterises the heavy-metal content in leachates collected from eight landfills in France. In order to identify heavy metal occurrence in the different size fractions of leachates, a cascade filtration protocol was applied directly in the field, under a nitrogen gas atmosphere to avoid metal oxidation. The results of analyses performed...

An in situ Porewater Chemistry (PC) experiment in the Opalinus Clay formation was carried out at the Mont Terri underground rock laboratory (Jura Mountains, Switzerland) for a period of 5 a. A traced water with a composition close to that expected in the formation was continuously circulated and monitored in a packed-off borehole to achieve diffusi...

Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation dur...

An in situ test in the Opalinus Clay formation, termed porewater chemistry (PC) experiment, was carried out for a period of 5 years. It was based on the concept of diffusive equilibration whereby a traced water with a composition close to that expected in the formation was continuously circulated and monitored in a packed-off borehole. The main ori...

The chemistry of pore water (particularly pH and ionic strength) is an important property of clay rocks being considered as host rocks for long-term storage of radioactive waste. Pore waters in clay-rich rocks generally cannot be sampled directly. Instead, their chemistry must be found using laboratory-measured properties of core samples and geoche...

The Callovian–Oxfordian (COx) clayey unit is being studied in the Eastern part of the Paris Basin at depths between 400 and 500 m depth to assess of its suitability for nuclear waste disposal. The present study combines new mineralogical and isotopic data to describe the sedimentary history of the COx unit. Petrologic study provided evidence of the...

A pluridisciplinary approach was used to define iodine immobilization mechanisms by biocarbonates in a natural marine carbonate-bearing clayey formation. For this purpose, different techniques of observation (optical microscope, scanning electron microscope (SEM), cathodoluminescence (CL)) and of analyses (infrared spectrometry (IR), electron micro...

In the context of waste confinement, concrete may be used both as a confinement and as a building material. Concerning radwaste, the heat released during radioactive decay will modify the equilibrium constants of the minerals forming the concrete. The present work aims to elucidate the temperature dependency of the thermodynamic functions related t...

A concrete/clay-stone (contact A) and a cement/clay-stone (contact B) interface have been sampled in the Meuse Haute Marne Underground Research Laboratory (MHM-URL) operated by ANDRA. Contact A is mainly characterized by (1) the dissolution of the portlandite in the concrete depth, (2) the carbonation of the concrete and (3) the precipitation of gy...

In the context of waste confinement and, more specifically, waste from the nuclear industry, concrete is used both as a confinement and as a building material Its exposure to high temperatures makes its geochemical behavior difficult to predict over large periods of time The present work aims to elucidate the solubility constants, as a function of...

Strontium is a good monitor of geochemical processes in natural clayey formations. In the Callovian-Oxfordian formation of Bure in France, strontium is sorbed on clay minerals and carried by carbonates, detrital minerals and accessory celestite. In order to determine the strontium distribution among these different phases, four-step sequential extr...

One site under consideration for the disposal of medium and high level, long lived radioactive waste is in the eastern part of the Paris Basin (Meuse/Haute Marne, France), where the National Radioactive Waste Management Agency (ANDRA) operates an underground laboratory. The sedimentary host formation is a 130 m thick, clay-rich Callovo-Oxfordian de...

Concrete and cement in contact with Callovian-Oxfordian (COx) clay have been sampled in the Meuse/Haute Marne Underground Research Laboratory operated by ANDRA. Carbon and oxygen isotopes on carbonates and strontium isotopes on exchangeable, as well as calcite fractions on both materials, strongly suggest that interactions (isotopic exchange, disso...

Thermodynamic functions and adsorption of water molecules are very important properties for clay minerals. Smectite MX-80 and mixed-layer illite-smectite ISCz-1 were selected. They were first carefully characterized (HRTEM with EDX analysis), revealing original results. Then, the thermodynamic properties of water in clay were obtained by (i) compar...

A concrete/clay-stone (contact A) and a cement/clay-stone (contact B) interface have been sampled in the Meuse Haute Marne Underground Research Laboratory (MHM-URL) operated by ANDRA. Contact A is mainly characterized by (1) the dissolution of the portlandite in the concrete depth, (2) the carbonation of the concrete and (3) the precipitation of gy...

Concrete and cement in contact with Callovian-Oxfordian (COx) clay have been sampled in the Meuse/Haute Marne Underground Research Laboratory operated by ANDRA. Carbon and oxygen isotopes on carbonates and strontium isotopes on exchangeable, as well as calcite fractions on both materials, strongly suggest that interactions (isotopic exchange, disso...

An initial geochemical characterization of clayrocks is needed in order to evaluate their feasibility for use as caprocks or host formations for greenhouse gas storage or nuclear waste disposal facilities, respectively. In this context, a method was developed for the measurement of CO2 partial pressure in clayrock pore water. The PCO2 was systemati...

Iodine is one of the most problematic radioisotopes in the context of nuclear waste geological disposal due to its high mobility. Considerable effort has been dedicated to the measurement of its potential retardation during diffusive transport leading to conflicting results, from no retardation to significant retardation, leading in turn to conside...

The heat capacities of the international reference clay mineral chlorite CCa-2 from Flagstaff Hill, California, were measured by low temperature adiabatic calorimetry and differential scanning calorimetry, from 5 to 520K (at 1bar). The studied chlorite is a Fe-bearing trioctahedral chlorite with an intermediary composition between ideal clinochlore...

Sodium-K, Na-Ca, Na-Mg, and Na-Sr exchange isotherms were performed at a total CI concentration of about 0.005 mol L(-1) on the fine fraction (<2 mu m) of MX80 montmorillonite, mixed-layer illite smectite minerals (IS), and clayey stones from European underground research laboratories. The derived selectivity coefficients for Na-K, Na-Ca, Na-Mg, an...

In underground repository concepts for radioactive waste, bentonite is studied as a reference swelling material to be used as an engineered barrier. Under the changing geochemical conditions prevailing within the barrier (saturation with the fluid coming from the host formation, diffusion of various chemical plumes caused by the degradation of some...

The Underground Research Laboratory of Bure, located in the Eastern part of the Paris Basin, was selected by ANDRA (French Agency for Nuclear Management) in order to study the feasibility of a nuclear waste disposal in the Callovian-Oxfordian thick clayey formation at 400 meters depth. Since 1994's, numerous investigations have been initiated to un...

Large quantities of cements and concretes need to be incorporated in geological disposal facilities for long-lived radwaste. An alkaline plume diffusing from an aged concrete (pH ∼ 12.5) through argillite-type rocks has been modelled considering feedback of porosity value variations on transport properties using the reactive transport code TOUGHREA...

n.marty@brgm.fr) (C.Tournassat@brgm.fr) (e.gaucher@brgm.fr) (burnol@brgm.fr) 2. Andra, Agence nationale pour la gestion des déchets radioactifs, 1/7 rue Jean Monnet, F-92298 Châtenay-Malabry Cedex, France (eric.giffaut@andra.fr) INTRODUCTION The Callovo-Oxfordian clayey formation (COX) is a natural barrier with a strong potential of confinement. Ho...

Iron and Sr bearing phases were thoroughly investigated by means of spectrometric and microscopic techniques in Callovian–Oxfordian (COX) samples originating from the ANDRA Underground Research Laboratory (URL) in Bure (France). Strontium was found to be essentially associated with celestite, whereas Fe was found to be distributed over a wide range...

This work presents an XRD pattern model applied to the quantification of clay minerals in the <2 μm fraction. The model is based on a linear combination of patterns previously simulated with specific codes. The modeling procedure is especially adapted to the oriented deposits performed from a suspension although it can also apply to the oriented pa...

Iodide sorption experiments were conducted on clay stone samples originating from the Callovian–Oxfordian formation under experimental conditions as close as possible to in situ conditions. The total natural iodine content of the formation is shown to be very constant throughout the formation, ranging from 2 to 3ppm. This range is in agreement with...

The heat capacities of the anhydrous international reference clay minerals, smectite MX-80, illite IMt-2 and mixed-layer illite–smectite ISCz-1, were measured by low temperature adiabatic calorimetry and differential scanning calorimetry, from 6 to 520 K (at 1 bar). The samples were chemically purified and Na-saturated. Dehydrated clay fractions <2...

INTRODUCTION For long-lived intermediate-level radioactive waste, the use of concrete as engineering barrier and Callovian-Oxfordian clay as geological barrier at a depth of 500 m is considered in the French disposal concept (ANDRA, 2005). Upon emplacement, initially unsaturated concrete is expected to experience coupled processes involving heating...

Poster Tough Symposium, Berkeley 2007

Na/K, Na/Ca and Na/Mg exchange isotherms were performed on the fine fraction (<2 μm) of Imt-2 illite samples at a total normality of about 0.005 mol/L in anionic chloride medium. The derived selectivity coefficients for Na/K, Na/Ca and Na/Mg were found to vary as a function of the exchanger composition and compared well with the data collected in t...

In ANDRA's studies to characterize the Callovian-Oxfordian formation, porewater chemistry is a key topic. Indeed, chemistry determines the durability of the repository materials (bentonite, concrete, metals, nuclear glass) and the speciation (and thus the mobility) of radionuclides. The method developed in the frame of the THERMOAR project enables...

The mineral alteration in the concrete barrier and in the clay formation around long-lived intermediate-level radioactive waste in the French deep geological disposal concept is evaluated using numerical modeling. There are concerns that the mineralogical composition of the surrounded clay will not be stable under the high alkaline pore fluid condi...

The concept of storing radioactive waste in geological formations calls for large quantities of concrete that will be in contact with the clay material of the engineered barriers as well as with the geological formation. France, Switzerland and Belgium are studying the option of clayey geological formations. The clay and cement media have very cont...

Congrès du 28 novembre 2005 au 01 décembre 2005

Congrès du 28.11.2005 au 01.12.2005

Congrès du 28.11.2005 au 01.12.2005

When a geosynthetic clay liner (GCL) containing sodium bentonite is brought into contact with fluids containing other cations, the latter may exchange with the sodium present between clay layers. This modification of clay surface chemistry may change the clay microstructure and hence its hydraulic conductivity. The influence of clay surface chemist...

Stable isotope characterization of porewater, and dissolved species, in mudrocks and argillaceous rocks is notoriously difficult. Techniques based on physical or chemical extraction of porewater can generate significant analytical artefacts. The authors report a novel, simple approach to determine the δ18O of porewater and δ13C of dissolved C in ar...

Historical Au-ore exploitation at the Chéni mine in the Massif Central, France, generated 525,000 tonnes of finely ground mill tailings deposited in a heap that has spread with time into three settling basins. The tailings, which are rich in quartz (80%), mica and clay minerals (10% of illite, smectite, kaolinite and chlorite), feldspars (5%) but p...

The design of clay plugs used for sealing access galleries to a radioactive waste repository built with concrete structures in a deep clayey formation must take into consideration their chemical evolution over time. Diffusion of an alkaline plume from concrete into bentonite was therefore modeled over a 100 ka period with the PHREEQC geochemical co...

Under the ANDRA Meuse/Haute Marne underground research laboratory scientific programme, two boreholes (EST204 and EST205) were drilled to a depth of 510 m for the purposes of scientific characterisation. Twenty-nine core samples were taken in borehole EST205 every 3 m between 422 and 504 m depth. Physical property measurements (water content, poros...

Description Ten-peer reviewed papers give you the latest information on geosynthetic clay liner (GCL) technology. Topics address the ability of the current ASTM standards to assess GCLs, and how they can be improved to better meet the needs of the industry; compatibility and longevity testing of GCLs; and new testing methods to advance the understa...

In relation with ANDRA research program assessing the potential of Callovo-Oxfordian argillites at Bure (Paris Basin) for underground disposal of nuclear waste, work is currently conducted at BRGM to determine the isotopic composition of present-day porewater and dissolved gases, in order to gain knowledge in the origin of interstitial water and in...

The Mont Terri geochemical program successfully achieved its goals of characterising and identifying controls on in situ pore water chemistry, describing transport processes and the geochemical evolution at the site, and evaluating practical techniques for characterising pore water in clay rock. Both field and laboratory techniques were investigate...

One approach to characterise the pore water composition in a claystone of low-permeability is based on geochemical modelling using data from cation exchange and aqueous leachate experiments combined with mineralogical investigations. Aqueous leachate data provide general information about the chemical type and-when combined with adequate (i.e. geoc...