Using tracer experiments to determine deep saline aquifers caprocks transport characteristics for carbon dioxide storage

It is shown how a simple gas tracer technique can contribute to the determination of transport characteristics of tight rock formations. Main obtained parameters are intrinsic permeability and the Klinkenberg coefficient; permeability as low as 10-21 m2 is easily attainable. Some information is also gained on diffusion characteristics and porosity. An example of application is given using caprocks from a deep saline aquifer in the Paris basin

Amélioration des techniques de reconstitution en espèces feuillues de la forêt méditerranéenne

Le reboisement est une des techniques de reconstitution possible de la forêt méditerranéenne, notamment après incendie. Si les techniques d'installation des résineux sont aujourd'hui bien maîtrisées, celles concernant les feuillus sont moins connues. Cette étude, à partir de dispositifs expérimentaux mis en place au début des années 1990, permet de tirer les premiers enseignements sur l'installation des plants feuillus

Notes for genera: basal clades of Fungi (including Aphelidiomycota, Basidiobolomycota, Blastocladiomycota, Calcarisporiellomycota, Caulochytriomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota, Mucoromycota, Neocallimastigomycota, Olpidiomycota, Rozellomycota and Zoopagomycota)

Compared to the higher fungi (Dikarya), taxonomic and evolutionary studies on the basal clades of fungi are fewer in number. Thus, the generic boundaries and higher ranks in the basal clades of fungi are poorly known. Recent DNA based taxonomic studies have provided reliable and accurate information. It is therefore necessary to compile all available information since basal clades genera lack updated checklists or outlines. Recently, Tedersoo et al. (MycoKeys 13:1--20, 2016) accepted Aphelidiomycota and Rozellomycota in Fungal clade. Thus, we regard both these phyla as members in Kingdom Fungi. We accept 16 phyla in basal clades viz. Aphelidiomycota, Basidiobolomycota, Blastocladiomycota, Calcarisporiellomycota, Caulochytriomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota, Mucoromycota, Neocallimastigomycota, Olpidiomycota, Rozellomycota and Zoopagomycota. Thus, 611 genera in 153 families, 43 orders and 18 classes are provided with details of classification, synonyms, life modes, distribution, recent literature and genomic data. Moreover, Catenariaceae Couch is proposed to be conserved, Cladochytriales Mozl.-Standr. is emended and the family Nephridiophagaceae is introduced

Release of clay particles from an unconsolidated clay-sand core experiments and modelling

International audienceRelease of clay particles from an unconsolidated clay-sand core experiments and modellingMarie-Helene Faure, Michel Sardin and Pierre Vitorge.This work identifies the main phenomena that control the peptisation and transport of clay particles in a sand core. Clay can be dispersed into small particles in an aqueous solution of low ionic strength. This property is used to generate clay particles with NaCl concentration varying from 0.5 M to 0.015 M. For this purpose, a chromatographic column is initially packed with a 5 percent clay-sand mixture. The monitored decrease of the NaCl concentration of the feed solution allows the control of transport of the particles without plugging the porous medium. In this conditions, it is shown that, in a column of a given length, the amount of clay particles, released into solution and available to transport, depends only on NaCl concentration. Some clay particles are available to migration when the NaCl concentration of the feed concentration is between 0.16 M and 0.05 M (first domain) or between 0.035 M and 0.019 M (second domain). An empirical function, P$_d$((NaCl)), accounts for this particle generation. Transport is mainly dependent on the hydrodynamic characteristics of the porous medium that vary during the elution, probably due to the particle motion inside the column. A phenomenological modelling is derived from these results, coupling the particle generation term, P$_d$((NaCl)), with an adapted nonequilibrium transport solute model. Similarly to the solute, particles were attributed a characteristic time of mass transfer between mobile and immobile water zones. This is sufficient to take into account the kinetic limitations of particles transport. The values of the parameters are determined by independent experiments. Finally, breakthrough curves of clay particles are predicted when a column of a given length is flushed by a salinity gradient of NaCl in various conditions

Use of tracers to characterize the effects of a CO2-saturated brine on the petrophysical properties of a low permeability carbonate caprock

International audienceTo assess the long-term safety of a geological carbon dioxide storage site, the confining properties of the rocks sealing an underground reservoir (caprocks) and their evolution inthe presence of CO2 must be characterized. The present study consists in the measurement of the transport parameters of dissolved CO2 through low permeability carbonate-rich caprocks. The properties of interest are the effective permeability and the diffusion coefficients of carbon dioxide dissolution products in water. The impact of carbon dioxide has been evaluated when altering rock samples by diffusion of a CO2-saturated brine under reservoir thermodynamic conditions, and by comparison of the pre- and post-alteration measured values. Permeability was measured by a gas-tracing method and, to study diffusion, radioactive isotopes of carbon (14C) and hydrogen (3H) were used. Despite a porosity increase observed for all the studied samples, the low values of transport parameters, measured initially, were also measured after alteration, showing a non-catastrophic alteration of the material

Hydrogen Content, Transport Properties And Light Degradation Of A-si:h Films Containing Artificially Generated Interfaces

Using different methods, intrinsic a-Si:H/a-Si:H interfaces were artificially generated in hydrogenated amorphous silicon films. Three types of interfaces were studied: (i) interfaces in which only the regrowth mechanisms were present; (ii) interfaces where both the regrowth mechanisms and the initial transient state of the discharge were present; and (iii) interfaces in which the initial transient state of the discharge was the dominant mechanism. The resulting material was characterized by measuring the hydrogen content, the electronic density of states, the transport properties and the film stability as a function of the interface type and density. It was found that samples containing interfaces of the first type are not very different from samples without interfaces and that transient discharge processes produce accumulation of hydrogen in the interface, which could relieve strains in the network. In order to investigate the influence of this strain-relieving mechanism on the Staebler-Wronski effect, p-i-n solar cells containing these H-rich interfaces were prepared and measured, together with "normal" cells. It was found that the former cells are more stable than the "normal" cells. The results of the present paper provide a new and promising way to circumvent the problem of the long term stability of hydrogenated amorphous solar cells. © 1988.171116Jackson, Biegelsen, Nemanich, Knights, (1983) Appl. Phys. Lett., 42, p. 105Collins, Pawlowski, (1986) J. Appl. Phys., 59, p. 1160Abeles, Yang, Persans, Stasiewski, Lanford, (1986) Appl. Phys. Lett., 48, p. 168Hundhausen, Santos, Ley, Habraken, Beyer, Primig, Gorges, (1987) J. Appl. Phys., 61, p. 556Nakayama, Ohtusuchi, Nakano, Kawamura, Initial transient phenomena in the plasma decomposition of silane (1985) Journal of Non-Crystalline Solids, 77-78, p. 757(1987) Partial results of the present paper were presented at the 7th EC Photovoltaic Solar Energy Conference, p. 555. , Sevilla, Spain, October 1986, Reidel, Dordrecht, HollandEquer, Huc, Lloret, Roca i Cabarrocas, Schmitt, (1987) Proc. 7th EC Photovoltaic Solar Energy Conf., p. 533. , Reidel, Dordrecht, HollandShanks, Fang, Ley, Cardona, Demond, Kalbitzer, (1980) Phys. Status Solidi, 100 B, p. 43Sardin, Andreu, Delgado, Esteve, Morenza, (1987) 7th EC Photovoltaic Solar Energy Conf., p. 577. , Reidel, Dordrecht, HollandJackson, Amer, (1982) Phys. Rev., 25 B, p. 5559Knights, Growth morphology and defects in plasma-deposited a-Si:H films (1980) Journal of Non-Crystalline Solids, 35-36, p. 159Kampas, Griffith, (1981) Appl. Phys. Lett., 39, p. 407Nguyen, Pan, (1984) Appl. Phys. Lett., 45, p. 134Ross, Johncock, Chan, (1984) J. Non-Cryst. Solids, 66, p. 81Abeles, Tiedje, Liang, Deckman, Stasiewski, Scanlon, Eisenberg, (1984) J. Non-Cryst. Solids, 66, p. 351Kampas, Griffith, Origin of emitting species in the plasma deposition of a‐Si:H alloys (1981) Journal of Applied Physics, 52, p. 1985Paduschek, Höpfl, Mitlehner, (1983) Thin Solid Films, 110, p. 291Phillips, (1979) J. Non-Cryst. Solids, 34, p. 153Cody, Tiedje, Abeles, Moustakas, Brooks, Goldstein, DISORDER AND THE OPTICAL ABSORPTION EDGE OF HYDROGENATED AMORPHOUS SILICON (1981) Le Journal de Physique Colloques, 42, pp. C4-301Lucovsky, Pollard, The Physics of Hydrogenated Silicon (1984) Topics in Appl. Phys., 56. , J.D. Joannopoulos, G. Lucovsky, Springer, FRGStaebler, Wronski, (1977) Appl. Phys. Lett., 31, p. 292Dersch, Stuke, Beichler, (1981) Appl. Phys. Lett., 38, p. 456Stutzmann, Jackson, Tsai, Kinetics of the Staebler–Wronski effect in hydrogenated amorphous silicon (1984) Applied Physics Letters, 45, p. 10Stutzmann, Jackson, Tsai, (1985) Phys. Rev., 32 B, p. 23Adler, (1983) Solar Cells, 9, p. 133Stutzmann, (1985) Appl. Phys. Lett., 47, p. 21I. Chambouleyron and F. Alvarez, unpublished dat