Το κίνητρο της παρούσας εργασίας είναι η μελέτη των μηχανισμών καταβύθισης μέσω της in-situ ανάμειξης και καταβύθισης δυσδιάλυτων αλάτων( ανθρακικό ασβέστιο) πάνω στις επιφάνειες αλλά και κατά μήκος των πορώδων υλικών. Οι επικαθίσεις δυσδιάλυτων αλάτων σε πορώδη σχηματισμούς, αποτελεί ένα σημαντικό πρόβλημα σε βιομηχανικές εφαρμογές. Για παράδειγμα, στην παγκόσμια βιομηχανία πετρελαίου και φυσικού αερίου πολλές περιοχές άντλησης πετρελαίου αντιμετωπίζουν τεράστιο πρόβλημα επικαθίσεων αλάτων, με αποτέλεσμα την δραματική μείωση της παραγωγής πετρελαίου. Επιπλέον, προβλήματα εναπόθεσης αλάτων μειώνουν την εκμετάλλευση γεωθερμικής ενέργειας, τη διάρκεια ζωής μεμβρανών αφαλάτωσης, καθώς και την απομόνωση του CO2 σε υπόγεια πηγάδια, κτλ. Οι επικαθίσεις αλάτων σε πηγάδια άντλησης πετρελαίου προέρχονται είτε από απευθείας καταβύθιση των διαλυμένων αλάτων που βρίσκονται στο νερό που υπάρχει σε υπόγειες κοιλότητες και καταβυθίζονται εξαιτίας της διαφοροποίησης των τοπικών συνθηκών(κυρίως πίεσης και θερμοκρασίας), είτε από τις μεγάλες ποσότητες νερού που χρησιμοποιείται για την εκτόπιση του πετρελαίου στα πηγάδια παραγωγής. Ένα από τα σημαντικότερα προβλήματα που αντιμετωπίζουν οι εταιρίες εξόρυξης πετρελαίου είναι οι μειωμένοι ρυθμοί άντλησης λόγω της μείωσης του τοπικού πορώδους και της διαπερατότητας από τη δημιουργία και την ανάπτυξης επικαθίσεων στα πηγάδια εξόρυξης. Οι επικαθίσεις αλάτων μπορούν επιπλέον να φράξουν τις σωληνώσεις ή να σχηματίσουν ένα λεπτό στρώμα στα τοιχώματα των σωληνώσεων που χρησιμοποιούνται στην παραγωγή. Ο σχηματισμός επικαθίσεων έχει σαν αποτέλεσμα την δημιουργία λειτουργικών προβλημάτων και δυσκολιών, που οδηγούν σε επιπλέον κόστος και σε εξαιρετικές περιπτώσεις στην εγκατάλειψη του πηγαδιού άντλησης πετρελαίου. Αρχικά έγινε μελέτη της αυθόρμητης καταβύθισης του ανθρακικού ασβεστίου σε αντιδραστήρες διαλείποντος έργου. Μελετήθηκε επίσης και η επίδραση της ίδιας ποσότητας άμμου σε διαφορετικούς αρχικούς υπερκορεσμούς κατά την αυθόρμητη καταβύθιση του ανθρακικού ασβεστίου. Καθ’ όλη τη διάρκεια των πειραμάτων συλλέγονταν δείγματα από τον αντιδραστήρα και ανιχνευόταν η μείωση της συγκέντρωσης των ιόντων ασβεστίων με τη μέθοδο της ατομικής απορρόφησης. Από τη μείωση της συγκέντρωσης των ιόντων ασβεστίου υπολογίστηκε ο ρυθμός καταβύθισης και στη συνέχεια η φαινόμενη τάξη της αντίδρασης και η σταθερά ταχύτητας. Σε όλα τα πειράματα ανιχνεύτηκε με περίθλαση ακτίνων Χ και ηλεκτρονική μικροσκοπία σάρωσης, ο ασβεστίτης ως η μοναδική καταβυθιζόμενη φάση. Κατά την αυθόρμητη καταβύθιση του ανθρακικού ασβεστίου απουσία άμμου, ο κύριος μηχανισμός καταβύθισης βρέθηκε ότι είναι η επιφανειακή διάχυση των δομικών μονάδων σε κατάλληλες θέσεις στην επιφάνεια των κρυστάλλων, ενώ στα πειράματα παρουσία ποσότητας άμμου οι κρύσταλλοι αναπτύσσονται με βάση το πολυπυρηνικό πρότυπο. Στην παρούσα εργασία μελετάται επίσης η διεργασία καταβύθισης του δυσδιάλυτου άλατος του ανθρακικού ασβεστίου (CaCO3) σε δισδιάστατα πορώδη δοκίμια Plexiglas®. Μέσω της οπτικής παρατήρησης της ανάπτυξης των επικαθίσεων, επιχειρήθηκε η εξαγωγή ποιοτικών και ποσοτικών πληροφοριών που αφορούν τους μηχανισμούς και τον τρόπο με τον οποίο αναπτύσσονται οι κρύσταλλοι ανθρακικού ασβεστίου στα τοιχώματα του προσομοιωτή πορώδους μέσου κάτω από ρεαλιστικές συνθήκες ροής, θερμοκρασίας και συγκέντρωσης. Δύο ευδιάλυτα διαλύματα χλωριούχου ασβεστίου, CaCl2, και όξινου ανθρακικού ασβεστίου, NaHCO3, αναμιγνύονταν λίγο πριν την είσοδό τους στο πορώδες μέσο με τη βοήθεια εμβολοφόρων αντλιών. Η καταβύθιση του ανθρακικού ασβεστίου λάμβανε μέρος μέσα στο πορώδες γραμμικό μέσο. Χρησιμοποιώντας ένα οπτικό μικροσκόπιο σε συνδυασμό με βιντεοκάμερα ήταν δυνατή η παρακολούθηση και η καταγραφή των κρυστάλλων που εμφανίζονταν καθώς και η ανάπτυξη τους κατά μήκος του καναλιού, στις θέσεις 2 cm, 6 cm, 8 cm και 10 cm από την είσοδο του. Σε κάθε θέση μετρήθηκε η μεταβολή του pH και της συγκέντρωσης του ασβεστίου με το χρόνο και επιπλέον καταγράφηκε ο σχηματισμός των κρυστάλλων του ανθρακικού ασβεστίου με τη βοήθεια της κάμερας του μικροσκοπίου. Για τη μέτρηση της συγκέντρωσης των ιόντων ασβεστίων χρησιμοποιήθηκε η φασματοφωτομετρία ατομικής απορρόφησης ενώ ο υπολογισμός του μεγέθους των κρυστάλλων έγινε με τη βοήθεια του προγράμματος Adobe Photoshop CS5.1. Κατά την διάρκεια του πειράματος ο υπερκορεσμός μειωνόταν κατά μήκος του καναλιού, ως αποτέλεσμα της in situ ανάμειξης των διαλυμάτων του χλωριούχου ασβεστίου και ανθρακικού νατρίου. Τέλος, κοντά στην είσοδο του καναλιού ο αριθμός και το μέγεθος των κρυστάλλων που καταβυθιστήκαν ήταν μεγαλύτερο, συγκριτικά με αυτούς που καταβυθιστήκαν κοντά στην έξοδο. / The deposition of sparingly soluble salts in porous formations is a severe problem encountered in industrial applications. For example, in international oil and gas industry many oil fields in operation face the major problem of scale which reduces dramatically oil production. Moreover, scaling problems limit the utilization of geothermal energy, the operational life of desalination membranes, in CO2 sequestration in subsoil wells, etc. Scale deposits encountered in oil fields are formed either by direct precipitation of the dissolved salts present in the formation water and precipitate because of the change of the local conditions (mainly pressure and temperature) or because of the large quantities of the injection water used for the displacement of the oil in the production wells. In the course of scale formation and development at wellbores, both local porosity and permeability may be reduced resulting in lower oil recovery rates. Scale deposits may also block flow by clogging perforations or by forming a thick layer on the wall of the production tubing. The formation of scales may result in a series of operational problems and difficulties, and in turn, result to additional capital cost, substantial operating cost and in extreme cases in the abandonment of the oil wells. The injection water (sea water) used in oil production is a stream most often incompatible with the well formation water. Mixing the incompatible streams interact chemically resulting in the precipitation of minerals. The high concentrations of SO42- in sea water and the low concentrations of Ba2+/Sr2+ in the formation waters constitute solutions where the concentrations of SO42- are low while the concentrations of Ca2+, Ba2+ and Sr2+ are high. Mixing of these streams, there is a high probability of CaSO4, BaSO4 and/or SrSO4 precipitation. Some of the more common ions frequently encountered in oil field waters and cause precipitation in incompatible waters are Ca2+, Ba2+, Sr2+, Fe2+, HCO3- and SO42-. In most cases, the low solubility and tenaciously adhering calcium carbonate and barium sulfate scale deposits are the most commonly salts found in well scale deposits. Knowledge of the mechanisms underlying the formation of scale deposits and the concomitant effects on the changes of the local porosity and permeability is of paramount importance for the efficient design of scale control processes. On the other hand there are beneficial applications involving the precipitation of insoluble salts. The controlled precipitation of sparingly soluble salts may be used for the effective consolidation of unconsolidated or poorly consolidated formations, like the sandy soils or granular materials (applications: protection of cultivated soils from erosion by raining water, protection of sandy reservoirs from the intrusion of sand grains within the oil wells, waterproofing of underground constructions, e.g. tunnels or other concrete constructions, etc). The main motivation for the present work is the investigation of the precipitation mechanisms through in-situ mixing and the precipitation of sparingly soluble salts (calcium carbonate) in porous materials. The proposed method may be applicable for the prevention of sand entrainment into well bores during oil production in poorly consolidated oil reservoirs. In the present study two series of experiments were done in order to investigate the kinetics of calcium carbonate precipitation in batch reactors using calcium chloride and sodium bicarbonate as the initial reagents in the absence and presence of sand. In all supersaturated solutions used in the present work, the stoichiometric of total calcium ions to total bicarbonate ions was equal to 1:1. During the experiments samples were taken, filtered through membrane filters and analyzed for total calcium by atomic absorption spectroscopy. The analysis of the kinetic data showed that in spontaneous precipitation experiments the crystals grow with spiral mechanism (n=2) and in the presence of sand kinetics data were best fitted by the polynuclear model (n>2). At the end of each experiment, the fluid suspension was filtered with a 0.22 μm filter and the solids were collected, dried at room temperature, and characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, also a series of experiments were done using two dimensional porous (Plexiglas®) medium models in which insoluble salts were nucleated from supersaturated solutions. Through the direct observation of the evolution of the deposits it was attempted to obtain qualitative and quantitative information concerning the mechanisms and pattern of deposition and growth of calcium carbonate scale on pore walls under realistic geometrical, flow, temperature and concentration conditions. Two soluble salts of calcium chloride, CaCl2, and sodium bicarbonate, NaHCO3, were mixed just before the injection point using syringe pumps. Precipitation of calcium carbonate took place within the porous medium. Using an optical microscope in combination with a video- camera it was possible to monitor crystal appearance and growth at a steady state. The growth of the calcium carbonate crystals in different positions within the etched linear porous medium as a function of time was observed. The visual observation of the crystal growth took place in different positions along the channel (2 cm, 6 cm, 8 cm and 10 cm from the inlet of the channel). In every position the changes of the pH and calcium concentration were measured and the formation of crystals was recorded through image capture. During the flow of the mixture through the channel, supersaturation decreased as a result of the in situ mixing of calcium and bicarbonate ions. As it was expected precipitation was favoured near the inlet of the cell and few crystals were precipitated near the outlet. Furthermore, the size of the crystal was bigger near the inlet of the channel in comparison to the crystals that have precipitate near the outlet of the channel.

Les réservoirs carbonatés sont exploités pour leur réserve d’eau potable, de ressource géothermique ou le stockage géologique du dioxyde de carbone. Ces réservoirs sont difficiles à caractériser à cause d’une histoire diagénétique souvent complexe. Cette thèse offre de nouvelles perspectives sur la caractérisation des propriétés pétrophysiques et élastiques des calcaires urgoniens de Provence. Une approche intégrée et multi-échelle est proposée pour caractériser les propriétés pétrophysiques et élastiques des carbonates. Cette étude est basée sur des mesures de vitesse d’ondes P (Vp) et S (Vs) à l’échelle du laboratoire (centimètre–décimètre) et du terrain (mètre–décamètre). En laboratoire, les Vp et Vs ainsi que l’anisotropie sont mesurées sur des plugs et sur des carottes, en utilisant différentes fréquences centrales ultrasonores. Sur le terrain, l’approche consiste à mesurer les Vp et Vs entre deux puits distant de 2 m sur une profondeur de 14 m. Les mesures sont ensuite interprétées en fonction de la géologie observée aux échelles macro- et microscopiques. Les principaux résultats montrent que les Vp et Vs moyennes sont indépendantes de l’échelle de mesure, car elles sont dictées par la porosité. L’anisotropie causée par les fractures (15%) et les hétérogénéités (5%) se manifestent par une variabilité autour des vitesses moyennes. L’approche adoptée ici a permis de définir les interactions entre les propriétés de la matrice, les hétérogénéités, les fractures et les propriétés élastiques des roches carbonatées. Elle a montré que les propriétés élastiques tout comme les structures géologiques varient en fonction de l’échelle. / Carbonate reservoirs are also exploited for water production, geothermal energy, and carbon geological storage. Their Geophysical characterization remains challenging because of complex diagenetic history. This work offers new insights into the characterization of petrophysical, and elastic properties of the Urgonian limestones in the Provence region. An integrated multi-scale approach is proposed to characterize carbonate rocks petrophysical and elastic properties. This study relies on P- and S-wave velocity (Vp and Vs) measurements carried out at laboratory (centimeter–decimeter) and field (meter–decameter) scales. Laboratory scale Vp, Vs, and anisotropy are measured on plugs and cores, while on the field they are measured between two boreholes (crosshole) over a distance of 2 m and 14 m depth. The measurements are then compared to the geology from the macro- to the microscopic scale. The main results show that the average Vp and Vs are porosity related, and are independent from scale. Anisotropy caused by fractures (15%) and heterogeneities (5%) is responsible for variations around the mean velocities. The approach adopted during this work has enabled to scope out the interplay between matrix properties, heterogeneity, fracturing, and elastic properties in carbonate rocks. It has shown that the elastic properties evolve with scale as well as the geological structures.

Compósitos de polipropileno e carbonato de cálcio em escala nanométrica foram preparados através de processamento em extrusora de rosca dupla co-rotacional. Metodologia estatística (projeto de experimentos) foi utilizada para avaliar o efeito das variáveis: teor de carbonato de cálcio, velocidade de rotação e configuração dos parafusos nas propriedades dos materiais obtidos. As propriedades mecânicas foram determinadas por meio de ensaios de tração (ASTM D 638), de resistência à flexão (ASTM D 790) e de resistência ao impacto (ASTM D 256). A processabilidade dos materiais foi avaliada através de determinações do índice de fluidez (ASTM D 1238). A microscopia eletrônica de varredura foi usada para avaliar a dispersão da carga na matriz e para obter informações sobre a adesão interfacial entre ambas. Os resultados obtidos demonstraram que o teor de carga adicionado ao polímero é a variável que exerce influência mais significativa sobre o módulo de flexão e que o teor de carga e a rotação dos parafusos são as variáveis que mais afetam as propriedades de impacto. O aumento da concentração das nanopartículas causou um aumento do módulo de flexão e da resistência ao impacto, enquanto que o aumento da velocidade de rotação dos parafusos provocou a redução das propriedades do impacto. A configuração do parafuso é a variável que tem um efeito mais significativo sobre a resistência mecânica do material. A utilização de um perfil de parafuso mais cisalhante promoveu a obtenção de valores mais altos de resistência à tração. A velocidade de rotação foi a variável mais significativa na determinação do módulo de Young. O aumento da velocidade de rotação associado à utilização da configuração do parafuso mais cisalhante da extrusora propicia um aumento do módulo de Young do polipropileno. Análise de microscopia eletrônica de varredura mostrou que não houve uma boa dispersão das nanopartículas na matriz polimérica e que, apesar de haver um revestimento das partículas com estearato de cálcio, há necessidade de se obter interações mais fortes entre a matriz polimérica e a carga inorgânica. A comparação entre os perfis de parafuso utilizados no processo de extrusão mostrou que materiais mais resistentes à flexão e ao impacto são obtidos a 350 rpm, utilizando a configuração de parafuso menos cisalhante. Há, entretanto, redução das propriedades de tração. Para obtenção de nanocompósitos de polipropileno e carbonato de cálcio, outras condições de processamento, e/ou outros procedimentos de revestimento das cargas devem ser testados de forma a promover melhor dispersão da carga e melhor interação entre carga e matriz.

Les interactions entre la fracturation, les circulations fluides et la chimie des fluides au sein de marges hyper-étendues sont encore peu décrites et sont pour la plupart localisées en mer, enfouies sous des sédiments post-rift. Le bassin sud Aquitain et la partie nord des Pyrénées constituent un cas d’étude approprié pour l’investigation de ces interactions dans un modèle de marge hyper-étendue avec exhumation du manteau durant le Crétacé inférieur puis inversée. Les données de terrain ont permis de décrire trois principaux sets de fractures. Ils ont été corrélés aux principaux événements de l’évolution géodynamique du bassin correspondant au rifting triasique, à l’hyper-extension datée Aptien-Cénomanien, et à la compression pyrénéenne. Les observations pétrographiques, les analyses Raman et microthermométriques sur les inclusions fluides, les données acquises par ICP-MS, et les analyses isotopiques ont permis de déterminer les chimies, les températures, les conditions rédox, les compositions des gaz, les signatures isotopiques de l’oxygène et du carbone, et les teneurs en terres rares des fluides parents pour les ciments précipités durant chaque épisode. Ces données ont permis le calage temporel des évènements diagénétiques majeurs. En particulier, la dolomie baroque et la chlorite ont précipité dans les fractures du set 2 durant l’hyper-extension correspondant au pic thermique à des températures supérieures à 300°C. La signature isotopique, la forte teneur en CO2, l’occurrence de H2S et les fortes salinités des fluides parents suggèrent la percolation de fluides mantelliques ascendants au travers des évaporites triasiques. La phase fin et post hyper-extension est caractérisée par de la bréchification hydraulique dans les formations les plus poreuses, une baisse des températures et des salinités, une baisse de la contribution mantellique dans les fluides parents, une fermeture du système diagénétique au cours de l’enfouissement et un passage à des conditions réductrices durant la précipitation du quartz, de la pyrite et de la calcite. La phase de compression pyrénéenne associée au troisième stade de fracturation a induit une réouverture du système diagénétique et favorisé le retour à des conditions oxydantes et à des infiltrations de fluides météoriques / Interactions between fracturing, fluid circulations and fluid chemistry on hyper-extended margins is still poorly described as most of them are located offshore, buried underneath post-rift sediments. The southern Aquitaine basin and the northern Pyrenees constitute an appropriate case study to investigate these interactions since a model of hyper extended margin with mantle exhumation during the Lower Cretaceous subsequently inverted was recently proposed. From a field study, we here describe three main sets of fractures (set 1 to set 3). They are correlated with main stages of the geodynamic evolution of the basin corresponding to the Liassic rifting, the Aptian-Cenomanian hyper-extension, and the Pyrenean compression. Petrographic observations, Raman and micro-thermometry analysis on fluid inclusions, ICP-MS, and isotope analysis permitted to determine chemistries, temperatures, redox conditions, gas compositions, oxygen and carbon isotopic signatures, and REE contents of parent fluids for cements precipitated during each episode. In particular saddle dolomite and chlorite precipitated in set 2 fractures during the hyper-extension corresponding to the thermal peak at temperatures higher than 300°C. The isotopic signature, the high CO2 content, the occurrence of H2S and the high salinity of parent fluids suggest ascending mantle fluids percolating across Triassic evaporites. The late and post hyper-extensional phase is characterized by hydraulic brecciation in porous formations, a decrease in temperature and salinity, a decrease in mantle contribution in parent fluids, a closing of the diagenetic system during burial and a switch to reducing conditions during the precipitation of quartz, pyrite and calcite. The Pyrenean compressive phase associated with the third fracturing stage induced a reopening of the diagenetic system and favored a return to oxidizing conditions and infiltrations of meteoric fluids

Magister Scientiae - MSc (Chemistry) / The anode catalyst is one of the important parts of the direct alcohol fuel cell (DAFC); it is responsible for the alcohol oxidation reaction (AOR) takes place at the anode side. Pd has been reported to have good alcohol oxidation reactions and good stability in alkaline solution. Better stability and activity has been reported for Pd alloyed catalysts when compared to Pd. Choosing a suitable alcohol also has an effect on the activity and stability of the catalyst. This study investigates the best catalyst with better AOR and the best stability and also looks at the better alcohol to use between glycerol and ethanol for the five in-house catalysts (20% Pd, PdNi, PdNiO, PdMn3O4 and PdMn3O4NiO on multi walled carbon nanotubes) using cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectrometry (EIS) and chronoamperometry. HR-TEM and XRD techniques were used to determine the particle size and average particle size, respectively while EDS used to determine elemental composition and ICP was used to determine catalyst loading. It was observed from LSV that PdNiO was the most active catalyst for both ethanol and glycerol oxidation, and it was the most stable in ethanol while PdMn3O4 proved to be the most stable catalyst in glycerol observed using chronoamperometry. The best alcohol in this study was reported to be glycerol having given the highest current densities for all the inhouse catalysts compared to ethanol observed using LSV. From XRD and HR-TEM studies, particle sizes were in the range of 0.97 and 2.69 nm for XRD 3.44 and 7.20 nm for HR-TEM with a little agglomeration for PdMn3O4 and PdMn3O4NiO.

Une fois déposé, un sédiment est affecté au cours de son enfouissement par un ensemble de processus, regroupé sous le terme diagenèse, le transformant parfois légèrement ou bien suffisamment pour le rendre méconnaissable. Ces modifications ont des conséquences sur les propriétés pétrophysiques qui peuvent être positives ou négatives, c'est-à-dire les améliorer ou bien les détériorer. Une voie alternative de représentation numérique des processus, affranchie de l'utilisation des réactions physico-chimiques, a été adoptée et développée en mimant le déplacement du ou des fluides diagénétiques. Cette méthode s'appuie sur le principe d'un automate cellulaire et permet de simplifier les phénomènes sans sacrifier le résultat et permet de représenter les phénomènes diagénétiques à une échelle fine. Les paramètres sont essentiellement numériques ou mathématiques et nécessitent d'être mieux compris et renseignés à partir de données réelles issues d'études d'affleurements et du travail analytique effectué. La représentation des phénomènes de dolomitisation de faible profondeur suivie d'une phase de dédolomitisation a été dans un premier temps effectuée. Le secteur concerne une portion de la série carbonatée de l'Urgonien (Barrémien-Aptien), localisée dans le massif du Vercors en France. Ce travail a été réalisé à l'échelle de la section afin de reproduire les géométries complexes associées aux phénomènes diagénétiques et de respecter les proportions mesurées en dolomite. De plus, la dolomitisation a été simulée selon trois modèles d'écoulement. En effet, la dédolomitisation étant omniprésente, plusieurs hypothèses sur le mécanisme de dolomitisation ont été énoncées et testées. Plusieurs phases de dolomitisation per ascensum ont été également simulées sur des séries du Lias appartenant aux formations du groupe des Calcaire Gris, localisées au nord-est de l'Italie. Ces fluides diagénétiques empruntent le réseau de fracturation comme vecteur et affectent préférentiellement les lithologies les plus micritisées. Cette étude a permis de mettre en évidence la propagation des phénomènes à l'échelle de l'affleurement. / Once deposited, sediment is affected by diagenetic processes during their burial history. These diagenetic processes are able to affect the petrophysical properties of the sedimentary rocks and also improve as such their reservoir capacity. The modelling of diagenetic processes in carbonate reservoirs is still a challenge as far as neither stochastic nor physicochemical simulations can correctly reproduce the complexity of features and the reservoir heterogeneity generated by these processes. An alternative way to reach this objective deals with process-like methods, which simplify the algorithms while preserving all geological concepts in the modelling process. The aim of the methodology is to conceive a consistent and realistic 3D model of diagenetic overprints on initial facies resulting in petrophysical properties at a reservoir scale. The principle of the method used here is related to a lattice gas automata used to mimic diagenetic fluid flows and to reproduce the diagenetic effects through the evolution of mineralogical composition and petrophysical properties. This method developed in a research group is well adapted to handle dolomite reservoirs through the propagation of dolomitising fluids and has been applied on two case studies. The first study concerns a mid-Cretaceous rudist and granular platform of carbonate succession (Urgonian Fm., Les Gorges du Nan, Vercors, SE France), in which several main diagenetic stages have been identified. The modelling in 2D is focused on dolomitisation followed by a dedolomitisation stage. For the second study, data collected from outcrops on the Venetian platform (Lias, Mont Compomolon NE Italy), in which several diagenetic stages have been identified. The main one is related to per ascensum dolomitisation along fractures. In both examples, the evolution of the effects of the mimetic diagenetic fluid on mineralogical composition can be followed through space and numerical time and help to understand the heterogeneity in reservoir properties.

Au Crétacé inférieur, l'intense activité magmatique due à la dislocation du super-continent Pangée influence fortement les conditions environnementales globales. Au Barrémien terminal et Aptien basal, période géologique dont fait l'objet cette étude, le bassin Vocontien, puis Bédoulien, recouvre le Sud-Est de la France, sous un climat chaud et humide. Sur les bordures de ces bassins, des plateformes carbonatées se mettent en place. Les sédiments qui se déposent sur ces plateformes sont à l'origine de la formation urgonienne. Afin d'étudier cette formation, une charte biostratigraphique, principalement basée sur les Orbitolinidés, et un modèle de faciès ont été développés. Les assemblages faunistiques, la succession des faciès, les observations de terrain ainsi que l'étude de signaux géochimiques ont permis le découpage séquentiel de la série urgonienne le long de 54 coupes et puis, répartis sur l'ensemble du Sud-Est de la France. Les corrélations induites par cette étude stratigraphique ont mis en évidence d'importantes variations d'épaisseur et d'environnements de dépôt au sein même de la plateforme urgonienne. Ces variations sont expliquées par le jeu de failles syn-sédimentaires qui ont compartimentées la plateforme urgonienne en blocs. Sur la bordure sud du bassin Vocontien, ces failles d'orientation N30° et N110° délimitent six blocs basculés. Au sommet du Barrémien terminal, la subsidence des blocs situés le plus au sud s'amplifie jusqu'à provoquer l'ouverture du bassin de la Bédoule au sud du secteur d'étude. Cette théorie d'évolution a ensuite été testée par l'élaboration d'un modèle numérique en trois dimensions de l'Urgonien du Sud-Est de la France. Sa cohérence avec les données acquises tout au long de cette étude d'une part, et sa cohérence géométrique d'autre part, valide les théories avancées. Des analogues de l'Urgonien sont répartis dans le monde entier et notamment au Moyen-Orient où ils représentent d'importants réservoirs pétroliers. Être capable de caractériser les facteurs ayant influencé l'architecture de l'Urgonien du Sud-Est de la France permet par la suite une meilleure exploitation de ses ressources énergétiques. / During the Early Cretaceous epoch, intensive magmatic activity due to the dislocation of the super-continent Pangaea, highly influenced global environmental conditions, which were characterized by a warm and generally humic climate. In this context, carbonate platforms were important in tropical and subtropical shallow-water regions, and especially during the late Barremian and early Aptian, platform carbonates of so-called Urgonian affinity are widespread. In southeastern France, the Urgonian platform was part of the northern Tethyan margin and bordered the Vocontian and the Bedoulian basins. The goal of this thesis was the systematic study of the Urgonian Formation in this region, and in order to achieve this goal, a biostratigraphic chart and a facies model were developed. The faunistic assemblages, the facies succession, the field observations and the study of geochemical signals lead to a sequential subdivision of the Urgonian series along 54 sections and wells allocated in five different regions in southeastern France (Gard, Ardèche, Vercors, Vaucluse and Provence). Correlations from this stratigraphic study highlight important variations in thickness and depositional environments of the Urgonian series. These variations are explained by relative movements induced by syn-sedimentary faults, which divided the Urgonian platforms into blocks. On the southern border of the Vocontian basin, these faults, oriented N30° and N110°, delineate six tilted blocks. At the top of the upper Barremian carbonates, subsidence of the two southern blocks accelerated leading to the opening of the Bedoulian basin. The reconstruction of the sequence-stratigraphic and paleoenvironmental evolution of the Urgonian platforms was then tested by the construction of a 3D numerical model of the Urgonian formation of southeastern France. Firstly, its consistency with the data collected during this study, and secondly, its geometrical coherence validate the proposed theory. Urgonian analogs exist all over the world and particularly in Middle East where they constitute important oil reservoirs. The exact reconstruction of the major factors, which influenced the architecture of these formations, will allow for a better exploitation of these energy resources.

Made available in DSpace on 2014-06-11T19:23:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-26Bitstream added on 2014-06-13T20:50:51Z : No. of bitstreams: 1 valentinineto_r_me_araca.pdf: 1016804 bytes, checksum: 73fcc7bf3ee8807a59e2a2d1298a5c30 (MD5) / Proposição: Este estudo teve como objetivo avaliar, através de estudo microscópico por análises histológica, histométrica e imunoistoquímica, o comportamento ósseo frente à presença de cimento de fosfato-carbonato de cálcio em defeitos experimentais. Materiais e Método: Foram confeccionados defeitos não-críticos em tíbias de 30 ratos machos adultos (Rattus norvegicus albinus, Wistar), em dois grupos, Controle e Tratado. As lâminas foram obtidas nos períodos de 10, 20 e 30 dias pósoperatórios e as imagens teciduais foram analisadas qualitativa e quantitativamente. Resultados: Não houve diferença estatística na área de neoformação óssea entre os grupos controle e tratado (P=0,258) e entre a expressão de RANK-L e OPG (P=0,589). Observou-se também áreas mínimas de invasão de tecido conjuntivo e periósteo com presença tardia do cimento em áreas distintas do defeito. Conclusão: De acordo com a metodologia aplicada, foi possível concluir que o uso de cimento de fosfato-carbonato de cálcio não alterou significativamente o processo de regeneração ósseo em tíbias de rato. / Proposition: This study had as objective evaluates, through histological, histometric and imuno-histochemical microscopic analysis, the bone behavior face to the presence of calcium phosphate-carbonate cement in experimental defects. Materials and Method: Non-critical defects were made in tibias of 30 adult male rats (Rattus norvegicus albinus, Wistar), in two groups, Control and Treated. The slices were obtained in the periods of 10, 20 and 30 postoperative days. The snapped images were quantitative and qualitative analyzed. Results: There was not statistics difference in the bone formation area (AO) between the groups control and treated (P=0,258) and between RANK-L and OPG expressions (P=0,589). It was also observed minimal areas of invasion of conjunctive tissue and periosteum with presence of the cement in areas different of the defect. Conclusion: In agreement with the applied methodology, it was possible to conclude that the use of calcium phosphate-carbonate cement didn't alter significantly the process of bone repair in rat tibias.

Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2016-07-20T13:56:54Z No. of bitstreams: 1 arquivototal.pdf: 5448320 bytes, checksum: 9dc55e9002b081eeb77f9fe4389b7313 (MD5) / Made available in DSpace on 2016-07-20T13:56:54Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 5448320 bytes, checksum: 9dc55e9002b081eeb77f9fe4389b7313 (MD5) Previous issue date: 2015-03-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / One of the most important activities undertaken by the fishing communities of municipality of Cabedelo, PB, is the fishing clams. The beneficiation process generates a great quantity of shells after the mollusk extraction, whose disposal, in considerable amount, in mangrove environment, causes silting of large areas and environmental unbalance as consequence. On the other hand, the existence of the white ceramic products industries in Paraíba suggests the checking of possibility of using these clamshells, rich in calcium carbonate, in ceramic bodies’ compositions as well as replacement of calcite used in these compositions. The possibility of using these clamshells in porcelain tiles composition has been studied in this work present definite proportions aiming the optimization of the composition. Therefore, the porcelain tile mass, calcite and clamshells powder have been characterized by X-ray diffraction, X-ray fluorescence, thermal gravimetric analysis, thermal differential analysis and particle size analysis. After masses formulations, the test ceramic bodies has been obtained by uniaxial pressing. After sintered at 1210°C, 1220°C and 1230°C, the test ceramic bodies has been evaluated by technological tests, such water absorption, apparent porosity, flexural strength and linear shrinkage of drying and firing. The tests has been performed according to the recommendations of the ABNT relevant standards for BIa ceramic coating group. The results indicated which the incorporation of clamshells powder, up to 7% by weight, retains the properties of the ceramic bodies within the standards required by ABNT (13818/1997 – Placas cerâmicas para revestimentos – Especificação e Métodos de Ensaios). It has concluded which the introduction of the clamshells will be able to aggregate economic and social benefits, contributing to the environmental impacts reduction, caused by improper disposed of clamshells from processing of the fishing clams. / Uma das atividades de relevância desenvolvidas pela comunidade pesqueira do município de Cabedelo, PB, corresponde à pesca de mariscos. O processo de beneficiamento gera uma grande quantidade de conchas, após a extração do molusco, cujo descarte, em volume considerável, em ambiente de mangue, provoca assoreamento de grandes áreas e consequente desequilíbrio ambiental. Por outro lado, a existência de indústrias de produtos da cerâmica branca no Estado da Paraíba sugere a verificação da possibilidade de uso dessas conchas de mariscos, ricas em carbonato de cálcio, na composição dos corpos cerâmicos como também a substituição da calcita utilizada nessas composições. Neste trabalho estudou-se a possibilidade do uso de conchas de mariscos em massa de porcelanato, em proporções definidas, visando otimização da composição. Para tanto, a massa para porcelanato, a calcita e o pó de conchas foram caracterizados por difração de raios-X, fluorescência de raios-X, análise térmica gravimétrica, análise térmica diferencial e análise granulométrica. Após formulações das massas, foram conformados corpos de prova por prensagem uniaxial. Os corpos de prova, após queima nas temperaturas de 1210°C, 1220°C e 1230oC, foram avaliados por ensaios tecnológicos, como absorção de água, porosidade aparente, tensão de ruptura à flexão e retração linear de secagem e queima. Os testes foram realizados de acordo com as recomendações das normas ABNT para revestimentos cerâmicos do grupo BIa. Os resultados indicaram que a incorporação do pó de conchas, em até 7% em peso, mantém as propriedades dos corpos cerâmicos dentro dos padrões exigidos pela norma ABNT 13818/1997 – Placas cerâmicas para revestimentos – Especificação e Métodos de Ensaios. Concluiu-se que a introdução das conchas de mariscos pode agregar vantagens econômicas e sociais, contribuindo para a redução dos impactos ambientais causados pelo descarte inadequado dessas conchas resultante do beneficiamento da pesca artesanal de mariscos.

In this work, we report the synthesis of submicrometer calcium carbonate particles using the simplest approach of mixing solutions of calcium chloride and ammonium carbonate inorganic precursors in presence of crystallization modifiers. The typical crystallization of CaCO3 into large calcite crystals with rhombohedral morphology changed to very small (down to 0.8 μm) uniform spherical vaterite particles upon addition of small amounts (0.01 to 2.00 mg/mL) of the anionic homopolymer poly(sodium 4-styrenesulfonate) (PSS).The reaction temperature must be preferably kept low around 25 °C. Heating induces the formation of an unstable hydrated phase, which is quickly converted back to the most stable structure, however with some broadening in the particle size distribution. In contrast, large spheres made of a collection of calcite polycrystallite aggregates formed in presence of poly(acrylic acid) (PAA) under otherwise the same experimental conditions. Crystal growth in a preorganized environment created by selective distribution of Ca(II) ions onto the shell of polyestyrene-b-poly(acrylic acid) (PS-b-PAA) core-shell spherical micelles revealed a rather poor control of size and morphology. Therefore, PSS anionic homopolymer can be applied to the synthesis of submicrometer CaCO3 particles from solutions of inorganic salts, which is a much cheaper and sustainable method than controlled CO2 gas production and diffusion. Representative polymer@CaCO3 particle systems were used to prepare PCL-based composites, of which the rheological behavior was accessed by oscillatory rheology. / No presente trabalho, que se refere à síntese de partículas submicrométricas de carbonato de cálcio usando uma abordagem mais simples da mistura de soluções de cloreto de cálcio e carbonato de amônio, precursores inorgânicos na presença de modificadores de cristalização. A cristalização típica de CaCO3 em grandes cristais de calcita com morfologia romboédrica os quais sofreram alteração para partículas pequenas (abaixo de 0,8 um) e uniformes de vaterita se deu após a adição de pequenas quantidades (0,01 a 2,00 mg/ml) do homopolímero aniônico poli (estirenosulfonado de sódio) (PSS). A temperatura da reação deve ser preferencialmente mantida em torno de 25 °C. O aquecimento induz a formação de uma fase hidratada instável, que é rapidamente convertida para a estrutura mais estável, porém, com um aumento de tamanho da partícula. Em contrapartida, com a utilização de poli (ácido acrílico) (PAA), produziu-se grandes esferas formadas por um conjunto de agregados policristalinos de calcita sob as mesmas condições experimentais. O crescimento de cristais em um ambiente pré-organizado criado pela distribuição seletiva dos íons de Ca II na corona de poliestireno-b-poli (ácido acrílico) (PS-b- PAA), formando micelas esféricas do tipo núcleo- corona revelou um fraco controle do tamanho e da morfologia. Portanto, o homopolímero aniônico PSS pode ser aplicado à síntese de partículas submicrométricas de CaCO3 a partir de soluções de sais inorgânicos, tal método apresenta-se mais barato e sustentável tendo liberação de CO2 de forma controlada. Sistemas representativos de partículas de polímero@CaCO3 foram utilizados para preparar os compósitos à base de Poli (Caprolactona) (PCL), onde o comportamento reológico foi analisado por reologia oscilatória.