Anne Coudrain-Ribstein
Centre national de la recherche scientifique
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Featured researches published by Anne Coudrain-Ribstein.
Applied Geochemistry | 1993
Anne Coudrain-Ribstein; Philippe Gouze
The quantification of geochemical reactions in hydrothermal aquifers requires an exhaustive approach because of their interdependence. All chemical elements likely to have a quantitative influence on dissolution or precipitation reactions have to be taken into account. Geochemical constraints the number of which equals the number of the chemical elements, were determined with the help of chemical analyses of the solution. In the case study of the Dogger aquifer (Paris Basin, France), 12 elements are taken into account (Al, C, Cl, Ca, F, H, K, Mg, Na, O, S, Si). Three constraints apply to water-activity, neutrality and conservation of chloride in aqueous solutions. The determination of the remaining constraints was based on saturation indices, stability diagrams of minerals and partial pressure of carbon dioxide (pCO2). The present-day solutions are at equilibrium with respect to nine minerals (albite, anhydrite, chalcedony, calcite, dolomite, fluorite, kaolinite, K-feldspar and illite or chlorite). Thus, it was demonstrated that the composition of these solutions (including computed pCO2) is only a function of temperature and chloride content. Moreover, it was possible to test the validity of the geochemical system by computing its speciation and comparing these theoretical results with actual chemical analyses (pH and concentrations). Finally, geochemical simulations were used in predicting what quantities would be dissolved or precipitated, as either the temperature or the chlorinity varied. Although the rock is predominantly calcareous, these quantities could not be determined if the influence of the aluminosilicates were neglected. This chemical component approach with which one can pose and solve rigorously the chemical equilibrium problem constitutes a prerequisite for the quantitative study of geochemical processes related to fluid flow.
Comptes Rendus De L Academie Des Sciences Serie Ii Fascicule A-sciences De La Terre Et Des Planetes | 1998
Anne Coudrain-Ribstein; Bruno Pratx; Amal Talbi; Claude Jusserand
Abstract The approximately 20 published data based on isotopic profiles of the unsaturated zone lead us to express the evaporative flux as an inverse power function of the piezometric depth below the soil surface, independently of the soil characteristics. Recent publications report suction values taken at over 1 000 m from the soil surface in arid regions as well as hydraulic conductivities corresponding to these values. These new data allowed us to compute new bounds of the evaporative flux from aquifers in arid regions; they corroborate the weak influence of soil characteristics.
Natural resources research | 2000
Philippe Gouze; Anne Coudrain-Ribstein
A new model for simulating porosity and permeability changes caused by sedimentary reservoirsdiagenesis is presented. Permeability is computed from changes in the mineral volume fractionsresulting from precipitation and dissolution of the rock-forming mineral as fluid flows throughvariable salinity and temperature fields. Its evolution is controlled by a power—law relationship,in which a weighting coefficient is assigned to clay minerals. This approach allows theincorporation of the widely observed influence of clay content on the porosity—permeabilityrelationship. A synthetic example is set up to analyze the sensitivity of the results to a set offour controlling parameters: the effect of the clay-weighting coefficient compared to the effectof the salinity gradient, temperature gradient, and exponent coefficient of the permeabilityevolution law. Using a large range of values for these parameters, the results show that theirinfluence is of equivalent magnitude in terms of permeability evolution rate. It also seemsthat the value of the clay-weighting coefficient affects the evolution trend: permeability mayincrease when the porosity decreases (and vice versa). The model is compared to the classicalapproach for which permeability is a function of porosity change only. Results display thestrong influence of even low values of the clay-weighting coefficient on the permeabilitychange. Consequently, the specific influence of mineral transfers on pore structure changes isa key parameter for modeling permeability changes and cannot be bypassed by the use ofsimple porosity—permeability evolution law.
Bulletin de l'Institut Français d'Etudes Andines | 1995
Anne Coudrain-Ribstein; Bruno Pratx; J. Quintanilla; G.M. Zuppi; D. Cahuaya
Comptes Rendus De L Academie Des Sciences Serie Ii Fascicule A-sciences De La Terre Et Des Planetes | 1999
Philippe Weng; Anne Coudrain-Ribstein; Cyril Kao; Hocine Bendjoudi; Ghislain de Marsily
Journal of Geophysical Research | 2000
Jean-Denis Taupin; Anne Coudrain-Ribstein; Robert Gallaire; Gian Maria Zuppi; A. Filly
Sciences Géologiques, bulletins et mémoires | 1999
Anne Coudrain-Ribstein; Philippe Gouze
Sciences Géologiques, bulletins et mémoires | 1999
Philippe Gouze; Anne Coudrain-Ribstein; Riad Hassani; Dominique Bernard
Pangea | 1999
Roger Guérin; Marc Descloitres; Anne Coudrain-Ribstein; Amal Talbi; Edson Ramirez; Robert Gallaire
Bulletin de l'Institut français d'études andines, Variations climatiques etressources en eau en Amérique du Sud: importance et conséquences des événements El Niño | 1998
Anne Coudrain-Ribstein; Francis Sondag; Michel Loubet; Amal Talbi; Bernard Pouyaud; Claude Jusserand; Jorge Quintanilla; David Cahuaya; Robert Gallaire