Assessing Field Pressure and Plume Migration in CO2 Storages: Application of Case-specific Workflows at in Salah and Sleipner

AbstractPerformance assessment of CO2 geological storage aims at applying a specific workflow adapted to the site to be considered, using iterations between modeling tools and methods together with monitoring techniques. In the frame of the CO2ReMoVe European project site specific innovative workflows have been applied at In Salah (Krechba reservoir) and Sleipner (Utsira sand formation reservoir) to predict the reservoir pressure field and the associated CO2 plume migration. The workflows we applied benefit from appropriate site monitoring techniques: respectively InSAR satellite imaging for the Krechba reservoir and 4D Seismics for the Utsira sand formation storage. Indeed, simulation of the reservoir pressure and the plume migration are the two major modeling issues to deal with when considering storage efficiency and safety -together with public awareness when addressing the public acceptance issue

Poly(4-vinyl pyridine) radiografted PVDF track etched membranes as sensors for monitoring trace mercury in water

International audiencePoly-4-vinyl pyridine chains were radiografted inside the etched-tracks of PVDF nanoporous membrane. P4VP grafting was found to be localized on the solid PVDF surface. Coating of these PVDF-g-P4VP membranes with a very thin layer of gold results in an ASV electrochemical sensor. Functionalized ion track-etched PVDF-g-P4VP sensors were found very selective and highly sensitive for mercury LOD 5 ng/L. a b s t r a c t By a radiation-induced grafting technique, we have functionalized track-etched nanoporous polymer membranes with mercury sensitive poly-4-vinyl pyridine (P4VP). Coating of these membranes with a very thin layer of gold results in an electrochemical sensor that is very selective and highly sensitive for mercury LOD 5 ng/L – well below the norms for water (0.015 mg/L potable water and 0.5 mg/L residual waters-French water norms of 27 October 2011). E-beam irradiation permitted optimization of the radiografting synthesis on PVDF thin films prior to ion-track grafting. Synthesis and characterization by EPR, FESEM and FTIR are described in detail. A comparison between FTIR in ATR and transmission modes enabled us to localize the grafting on the surface of the e-beam irradiated PVDF films allowing us to extrapolate what happens on the etched tracks. Using Square Wave Anodic Stripping Voltammetry (SW-ASV), mercury concentrations of 1 mg/L are detected in 2 h and low ng/L concentrations are detected after 24 h of adsorption. The adsorption is passive so sensors do not require instrumentation and the analysis takes only 3–4 min. Also, the P4VP functionalized sensor appears insensitive to pH variations (pHs 3–9), high salt concentrations (up to 1 g/ L) and the presence of other heavy metals in the same solution.

The Nitrate Transporter MtNPF6.8 (MtNRT1.3) Transports Abscisic Acid and Mediates Nitrate Regulation of Primary Root Growth in Medicago truncatula

Elongation of the primary root during postgermination of Medicago truncatula seedlings is a multigenic trait that is responsive to exogenous nitrate. A quantitative genetic approach suggested the involvement of the nitrate transporter MtNPF6.8 (for Medicago truncatula NITRATE TRANSPORTER1/PEPTIDE TRANSPORTER Family6.8) in the inhibition of primary root elongation by high exogenous nitrate. In this study, the inhibitory effect of nitrate on primary root elongation, via inhibition of elongation of root cortical cells, was abolished in npf6.8 knockdown lines. Accordingly, we propose that MtNPF6.8 mediates nitrate inhibitory effects on primary root growth in M. truncatula. pMtNPF6.8:GUS promoter-reporter gene fusion in Agrobacterium rhizogenes-generated transgenic roots showed the expression of MtNPF6.8 in the pericycle region of primary roots and lateral roots, and in lateral root primordia and tips. MtNPF6.8 expression was insensitive to auxin and was stimulated by abscisic acid (ABA), which restored the inhibitory effect of nitrate in npf6.8 knockdown lines. It is then proposed that ABA acts downstream of MtNPF6.8 in this nitrate signaling pathway. Furthermore, MtNPF6.8 was shown to transport ABA in Xenopus spp. oocytes, suggesting an additional role of MtNPF6.8 in ABA root-to-shoot translocation. (15)NO3 (-)-influx experiments showed that only the inducible component of the low-affinity transport system was affected in npf6.8 knockdown lines. This indicates that MtNPF6.8 is a major contributor to the inducible component of the low-affinity transport system. The short-term induction by nitrate of the expression of Nitrate Reductase1 (NR1) and NR2 (genes that encode two nitrate reductase isoforms) was greatly reduced in the npf6.8 knockdown lines, supporting a role of MtNPF6.8 in the primary nitrate response in M. truncatula

4D Joint Stratigraphic Inversion of Prestack Seismic Data: Application to the CO2 Storage Reservoir (Utsira Sand Formation) at Sleipner Site Inversion stratigraphique jointe 4D de données sismiques avant sommation : application au réservoir de stockage de CO2 (Formation Utsira) du site de Sleipner

Seismic monitoring is commonly used in the oil industry to follow the evolution of reservoir properties during production. We present a methodology of time-lapse (or 4D) stratigraphic inversion, which is able to provide an estimation of P- and S-wave impedance variations in the reservoir by inverting prestack time-lapse seismic data. The 4D inversion is implemented in the time domain and requires a time scaling law for each repeated seismic dataset in order to adjust the arrival times of homologous events observed in the so-called reference and monitor datasets. This operation is often referred to as the warping problem. The 4D inversion is a 3-step methodology. The first step consists in inverting each seismic vintage independently, thus providing as many P- and S-wave impedance distributions as datasets considered. The second step uses the available P-wave impedance information to solve the warping problem which is crucial to the third and final step: the joint inversion of all available seismic vintages. This 4D inversion sequence was applied to seismic datasets recorded on the Norwegian CO2 storage reservoir of Sleipner field located in the North Sea. The latter is becoming a reference industrial site for the long-term storage of carbon dioxide (CO2) in a saline aquifer, the Utsira sand formation. We focused our 4D inversion study on the 1994 and 2006 vintages acquired two years before and ten years after the beginning of CO2 injection, respectively. The warping correction resulted in a time-scaling law with a maximum pushdown effect of about 45 ms at the base of the Utsira aquifer. The joint 4D inversion results show more consistency than the single 3D inversion results: the 4D inversion notably provides P-wave impedances for the CO2 -saturated sandstones which are close to the values derived from rock physics studies. <br> Le monitoring sismique est couramment utilisé dans l'industrie pétrolière pour suivre l'évolution des propriétés des réservoirs au cours de leur production. Nous présentons ici une méthodologie d'inversion stratigraphique 4D qui fournit une estimation des variations d'impédances des ondes P et S dans le réservoir, par inversion de données de sismiques répétées avant-sommation. L'inversion 4D est implémentée dans le domaine temps et nécessite une loi de mise à l'échelle des temps de trajets pour chaque jeu de données de sismique répétée (aussi appelé "millésime") afin de mettre en correspondance les temps d'arrivée d'événements homologues observés sur les jeux de données appelés référence et monitors. Cette opération est souvent appelée "warping". L'inversion 4D est une méthodologie qui comporte trois étapes : la première étape consiste à inverser chaque millésime sismique séparément, pour produire autant de distributions en impédances P et S que de jeux de données considérés. La seconde étape utilise l'information des impédances P disponibles pour résoudre le problème du warping, qui est un point clé pour la troisième et dernière étape : l'inversion jointe de tous les millésimes sismiques disponibles. Cette séquence d'inversion 4D a été appliquée aux jeux de données enregistrés sur le réservoir de stockage de CO2 du site norvégien de Sleipner (Mer du Nord). Ce dernier est devenu un site industriel de référence pour le stockage à long terme du dioxyde de carbone (CO2) dans un aquifère salin, la formation des sables de l'Utsira. Nous avons focalisé notre étude sur l'inversion 4D des millésimes 1994 et 2006, acquise respectivement avant et dix ans après le début de l'injection de CO2. Le warping a fourni une loi de mise à l'échelle des temps de propagation avec un retard maximum d'environ 45 ms à la base de l'aquifère Utsira. L'inversion 4D jointe a donné des résultats plus cohérents que les inversions 3D : l'inversion 4D fournit en particulier des impédances P pour les grès saturés en CO2 qui sont très proches des valeurs fournies par la physique des roches

MOCVD growth of ZnO nanostrutures using Au droplets as catalysts - art. no. 68950Z

International audienceZnO nanostructures were synthesised by Metal Organic Chemical Vapor Deposition growth on Si (100) and c-Al2O3 substrates coated with a 5nm thick layer of Au. The An coated substrates were annealed in air prior to deposition of ZnO so as to promote formation of Au nanodroplets. The development of the nanodroplets was studied as a function of annealing duration and temperature. Under optimised conditions, a relatively homogeneous distribution of regular An nanodroplets was obtained. Using the An nanodroplets as a catalyst, MOCVD growth of ZnO nanostructures was studied. Scanning electron microscopy revealed nanostructures with various forms including commonly observed structures such as nanorods, nanoneedles and nanotubes. Some novel nanostructures were also observed, however, which resembled twist pastries and bevelled-multifaceted table legs

MOCVD growth of ZnO nanostrutures using Au droplets as catalysts

International audienceZnO nanostructures were synthesised by Metal Organic Chemical Vapor Deposition growth on Si (100) and c-Al2O3 substrates coated with a 5nm thick layer of Au. The An coated substrates were annealed in air prior to deposition of ZnO so as to promote formation of Au nanodroplets. The development of the nanodroplets was studied as a function of annealing duration and temperature. Under optimised conditions, a relatively homogeneous distribution of regular An nanodroplets was obtained. Using the An nanodroplets as a catalyst, MOCVD growth of ZnO nanostructures was studied. Scanning electron microscopy revealed nanostructures with various forms including commonly observed structures such as nanorods, nanoneedles and nanotubes. Some novel nanostructures were also observed, however, which resembled twist pastries and bevelled-multifaceted table legs

Migration et politique au Moyen-Orient

Les migrations internationales constituent aujourd’hui, dans toutes les régions du globe, un enjeu majeur du politique. Elles font l’objet d’accords internationaux, engendrent des litiges diplomatiques et, surtout, défient en permanence l’ordre du « national ». L’immigrant se heurte à des frontières, spatiales et administratives ; l’émigrant renégocie en permanence ses relations à son pays d’origine. Aussi les migrations obligent-elles sans cesse à repenser les frontières, les manières de conceptualiser un territoire et, plus largement, la souveraineté politique d’un État-nation. Dans un Moyen-Orient arabe en pleine crise sociale, économique et politique, l’intensification des mouvements d’immigration et d’émigration, mais aussi celle des migrations de transit, est porteuse, en ce tournant de siècle, d’enjeux politiques spécifiques. L’implication accrue des diasporas dans les pays de départ, l’exploitation persistante des migrants dits « de travail », la présence des réfugiés de Palestine et, depuis peu, d’Irak ou du Soudan, les débats populaires que suscitent ces sujets, y posent de façon renouvelée la question du politique, des définitions de la nation à l’inscription régionale et internationale des États. Dans ce contexte émergent de nouveaux modes d’instrumentalisation, par les acteurs du politique, des mouvements migratoires intra-régionaux et internationaux, dont ce livre explore des exemples significatifs : « mobilité du travail et du capital » comme stratégie de politique intérieure et étrangère en Jordanie, rôle des États dans les migrations de travail (travail domestique en Jordanie et dans les pays du Golfe ; main-d’œuvre syrienne au Liban), gestion des réfugiés palestiniens dans les pays arabes, défi posé par les membres de cette diaspora à la rigidité des concepts de frontière et de citoyenneté portés par les acteurs du processus de paix, sort des réfugiés non palestiniens au Liban, caractère éminemment politique des débats sur la nationalité dans ce pays, rôle de l’Église maronite, acteur désormais transnational, sur la scène politique libanaise… Discours sur, représentation d’une identité nationale, instrument de politique intérieure mais aussi stratégie de relations internationales, les mesures de contrôle et de gestion des flux migratoires mettent en relief la pluralité croissante des notions de nationalité, de population nationale, de territoire, de même que les changements qui affectent les modalités du « contrat social ». Elles montrent la résilience des États et l’émergence de nouveaux acteurs dans la sphère du politique : réseaux ethnico-nationaux, religieux, réseaux d’affaires transnationaux… Les politiques migratoires éclairent ainsi de façon particulière les processus de construction nationale et de restructuration géopolitique à l’œuvre dans la région

Comparison of ZnO nanostructures grown using pulsed laser deposition, metal organic chemical vapor deposition, and physical vapor transport

International audienceThis article compares the forms and properties of ZnO nanostructures grown on Si(111) and c-plane sapphire (c-Al(2)O(3)) substrates using three different growth processes: metal organic chemical vapor deposition (MOCVD), pulsed laser deposition (PLD), and physical vapor transport (PVT). A very wide range of ZnO nanostructures was observed, including nanorods, nanoneedles, nanocombs, and some novel structures resembelling "bevelled" nanowires. PVT gave the widest family of nanostructures. PLD gave dense regular arrays of nanorods with a preferred orientation perpendicular to the substrate plane on both Si and c-Al(2)O(3) substrates, without the use of a catalyst. X-ray diffraction (XRD) studies confirmed that nanostructures grown by PLD were better crystallized and more highly oriented than those grown by PVT and MOCVD. Samples grown on Si showed relatively poor XRD response but lower wavelength emission and narrower linewidths in PL studie