A site selection methodology for CO2 underground storage in deep saline aquifers: case of the Paris Basin

International audienceSite selection is a fundamental step, which can condition the success of a CO2 geological storage. A CO2 storage has to gather several targets, which can be expressed through a list of criteria. In the proposed site selection methodology, these criteria can be classified into “killer criteria” and “site-qualification criteria”, whose combinations allow identifying potential sites and the most appropriate one(s). This multicriteria methodology is applied on the PICOREF study area, located in the Paris Basin, on which potential site(s) in deep saline aquifers are investigated

Carbon Monoliths with Hierarchical Porous Structure for All-Vanadium Redox Flow Batteries

Carbon monoliths were tested as electrodes for vanadium redox batteries. The materials were synthesised by a hard-templating route, employing sucrose as carbon precursor and sodium chloride crystals as the hard template. For the preparation process, both sucrose and sodium chloride were ball-milled together and molten into a paste which was hot-pressed to achieve polycondensation of sucrose into a hard monolith. The resultant material was pyrolysed in nitrogen at 750 ◦C, and then washed to remove the salt by dissolving it in water. Once the porosity was opened, a second pyrolysis step at 900 ◦C was performed for the complete conversion of the materials into carbon. The products were next characterised in terms of textural properties and composition. Changes in porosity, obtained by varying the proportions of sucrose to sodium chloride in the initial mixture, were correlated with the electrochemical performances of the samples, and a good agreement between capacitive response and microporosity was indeed observed highlighted by an increase in the cyclic voltammetry curve area when the SBET increased. In contrast, the reversibility of vanadium redox reactions measured as a function of the difference between reduction and oxidation potentials was correlated with the accessibility of the active vanadium species to the carbon surface, i.e., was correlated with the macroporosity. The latter was a critical parameter for understanding the differences of energy and voltage efficiencies among the materials, those with larger macropore volumes having the higher efficiencies.This work was supported by ICEEL and Region Grand Est and J.F.V.-V. was hired with these fundings. This work was partly supported by a grant overseen by the French National Research Agency (Pc2TES ANR-16-CE06-0012-01), and the authors involved in it (AC, BK and VF) acknowledge the support of the project's coordinator, Mrs Fouzia Achchaq. This study was partly supported by TALiSMAN project (2019-000214), funded by European Regional Development Fund (ERDF)

Contribution à la minéralogie et à géochimie des sédiments pélagiques profonds : comparaison des "blacks-shales" du crétacé dans l'atlantique central nord et des dépôts du malm et du crétacé en briançonnais

Cette comparaison repose sur : - l'analyse minéralogique semi-quantitative, aux rayons X L'analyse des teneurs et de la nature du carbone organique fournit des indications convergentes. - l'analyse géochimique des éléments majeurs et de 12 éléments traces (Sr, Ba, V, Ni, Co, Cr, B', Zn, Ga, Cu, Pb, Sn). Les résultats obtenus grâce aux "black- shales" de l'Atlantique servent de référence à l'étude des dépôts pélagiques profonds des Alpes. En particulier,la connaissance des corrélations entre composition minéralogique et composition chimique autorise, dans le cas des sédiments métamorphisés où seule la seconde est connue, une estimation de la première. - l'analyse des isotopes stables du carbone et de l'oxygène sur les calcaires de trois séries alpines d'âge jurassique supérieur à crétacé supérieur, permet de porter un jugement sur l' évolution spatiale et temporelle de la salinité et/ou de la température des eaux, à la surface du bassin téthysien, et aussi sur le niveau de la productivité organique. Des indications sont ainsi données sur d'éventuels confinements, et sur l'importance des circulations océaniques. La géochimie des éléments majeurs et traces et la géochimie isotopique, apportent des preuves convergentes d'une différence de nature entre les Terres Noires oxfordiennes et les argilites de faciès comparable du Crétacé moyen, en domaine briançonnais et sur ses bordures.Pas de résum

Solubilité de co2 dans les saumures des bassins sédimentaires (Application au stockage de co2 (gaz à effet de serre))

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

3D geomechanical modelling for CO2 geologic storage in the Dogger carbonates of the Paris Basin

CO2 injection into a depleted hydrocarbon field or aquifer may give rise to a variety of coupled physical and chemical processes. During CO2 injection, the increase in pore pressure can induce reservoir expansion. As a result the in situ stress field may change in and around the reservoir. The geomechanical behaviour induced by oil production followed by CO2 injections into an oil field reservoir in the Paris Basin has been numerically modelled. This paper deals with an evaluation of the induced deformations and in situ stress changes, and their potential effects on faults, using a 3D geomechanical model. The geomechanical analysis of the reservoir–caprock system was carried out as a feasibility study using pressure information in a “one way” coupling, where pressures issued from reservoir simulations were integrated as input for a geomechanical model. The results show that under specific assumptions the mechanical effects of CO2 injection do not affect the mechanical stability of the reservoir–caprock system. The ground vertical movement at the surface ranges from −2 mm during oil production to +2.5 mm during CO2 injection. Furthermore, the changes in in situ stresses predicted under specific assumptions by geomechanical modelling are not significant enough to jeopardize the mechanical stability of the reservoir and caprock. The stress changes issued from the 3D geomechanical modelling are also combined with a Mohr–Coulomb analysis to determine the fault slip tendency. By integrating the stress changes issued from the geomechanical modelling into the fault stability analysis, the critical pore pressure for fault reactivation is higher than calculated for the fault stability analysis considering constant horizontal stresses.Sandrine Vidal-Gilbert, Jean-Francois Nauroy and Etienne Bross

DC conductivity, cationic exchange capacity, and specific surface area related to chemical composition of pore lining chlorites

International audienceLow resistivity in argillaceous sandstone reservoirs may be attributed either to the effect of microporosity, or to specific effects due to intrinsic clays' conducting properties or to other conducting minerals. In order to distinguish these effects, cation exchange capacity, specific surface areas, and dc conductivity of various pore lining chlorite-bearing sandstones from different hydrocarbon reservoir measurements are investigated. Cation exchange capacity and specific surface area are measured on whole rocks as well as on size-separated fractions. Both sets of values are low, in agreement with the structural and textural observations. The conductivity of these chlorites, measured in air conditions and after dehydration, is investigated by means of complex impedance spectroscopy on size-separated fractions as a function of temperature and compared to that of reference clays. The results show a large influence of moisture, applied electric field frequency, and temperature on the electrical properties. The magnitude of the dehydrated clays' conductivity is such that its influence on the conductivity of argillaceous sandstone is lower than that related to the presence of water or brine by several orders of magnitude. The dc, conductivity and the related activation energy of the dehydrated samples appear to be related to the chemical composition of the clays. More specifically, a clear correlation occurs with the electrical charges of the clay network, that is to say with the location, i.e., tetrahedral or octahedral sites, of the substituting trivalent elements

An Integrated Model-based Tool Chain for Managing Variability in Complex System Design

International audienceSoftware-intensive systems in the automotive domain are often built in different variants, notably in order to support different market segments and legislation regions. Model-based concepts are frequently applied to manage complexity in such variable systems. However, the considered approaches are often focused on single-product development. In order to support variable products in a model-based systems engineering environment, we describe a tool-supported approach that allows us to annotate SysML models with variability data. Such variability information is exchanged between the system modeling tool and variability management tools through the Variability Exchange Language. The contribution of the paper includes the introduction of the model-based product line engineering tool chain and its application on a practical case study at Volvo Construction Equipment. Initial results suggest an improved efficiency in developing such a variable system

Reactive transport experiments and modelling of CO2 sequestration in deep aquifers

International audienceNot Availabl

Lignin-Based Carbon Nanofibers as Electrodes for Vanadium Redox Couple Electrochemistry

Three different types of lignin (kraft, organosolv and phosphoric acid lignin) were characterized and tested as precursors of electrospun nanofibers. Polyethylene oxide (PEO) was added as a plasticizer and dimethyl formamide (DMF) employed as a solvent. It was found that the molecular weight of lignin was the key parameter to understand the differences of the mechanical stability of the resultant fiber mats. In the case of kraft lignin (KL), the influence of some changes in the synthetic process was also tested: applied voltage, pretreatment in air or not, and the addition of a small amount of Ketjen black. After pyrolysis in nitrogen flow, the obtained carbon nanofibers (CNFs) were characterized by different techniques to analyze their differences in morphology and surface chemistry. Vanadium electrochemistry in 3M sulfuric acid was used to evaluate the different CNFs. All fibers allowed electrochemical reactions, but we observed that the oxidation of V(II) to V(III) was very sensitive to the nature of the raw material. Materials prepared from kraft and phosphorus lignin showed the best performances. Nevertheless, when 1 wt.% of Ketjen black was added to KL during the electrospinning, the electrochemical performance of the sample was significantly improved and all targeted reactions for an all-vanadium redox flow battery were observed. Therefore, in this work, we demonstrated that CNFs obtained by the electrospinning of lignin can be employed as electrodes for vanadium electrochemistry, and their properties can be tuned to improve their electrochemical properties