Unconventional gas resources have become important as an environment- friendly source of fuel. It is important to understand the pore level geometries of grains and voids in mudrocks in order to understand the flow potential of gas from these rocks. Recent observations of nanopores within carbonaceous material in mudrocks have led to the hypothesis that such material provides conduits for gas migration within the mudrock matrix. This hypothesis requires that the carbonaceous material exist not as isolated grains but as connected clusters of grains within the mudrock. To examine this hypothesis, we develop an algorithm for the grain-scale modeling of the spatial distribution of grains of carbonaceous matter in a matrix of non-carbonaceous material (silt, clay). The algorithm produces a grain-scale model of the sediment which is precursor to a mudrock, then a sequence of models of the grain arrangement as burial compacts the sediment into mudrock. The carbonaceous material is approximated by the simplest possible geometric model of spherical grains. These grains are distributed randomly within a population of other spheres that represent silt and clay grains. A cooperative rearrangement algorithm is used to generate a disordered packing of the grain mixture having a prescribed initial porosity. This model represents the sediment precursor of the shale in its original depositional setting. Periodic boundary conditions are imposed on the packing to eliminate wall-induced artifacts in the grain arrangement; in effect the packing extends infinitely in all three coordinate directions. We simulate compaction of the model sediment by incrementally rescaling the vertical coordinate axis, repeating the cooperative rearrangement calculation with periodic boundaries after each increment. We determine the size distribution of clusters of touching carbonaceous grains, focusing particularly upon the approach toward percolation (when a cluster spans the entire packing). The model allows estimation of threshold fraction of carbonaceous material for significantly connected clusters to form. Beyond a threshold degree of compaction, connected clusters become much more prevalent. Other factors affecting the threshold fraction such as ductility of the carbonaceous material is also evaluated. Ductility is modeled by taking a grain consisting inner rigid core covered by the outer soft shell which can be penetrated and deformed during geometrical transformation. The emergence of large numbers of clusters, or of a few large clusters, increases the probability that nanoporous conduits within the clusters would intersect a fracture in the mudrock. This should correlate with greater producibility of gas from the mudrock. Thus the dependence of the statistics of the clusters upon other parameters, such as the fraction of carbonaceous material, porosity, degree of compaction, etc., could be useful for estimating resource quality. For example, it is observed that the threshold concentration of carbonaceous material in the initial sediments for “significant clustering” enough to approach percolation is about 20 percent of the volume fraction. The degree of compaction needed to get “significant clustering” is 50%. / text

Raman-Spektroskopie an kohligem Material (RSCM) ist eine häufig verwendete Methode, um die maximale Temperatur der Metamorphose oder die thermische Reife von Kohlen und organikreichen Sedimenten zu bestimmen. Für die Temperaturabschätzung wurden bereits mehrere Kalibrationskurven ermittelt, jedoch wird die Übertragbarkeit dieser Kalibrationen auf andere Labore durch methodische Aspekte eingeschränkt und die Vergleichbarkeit zwischen den Laboren dadurch reduziert. Die subjektive Auswertung von Spektren, das verwendete Messsystem und die Probenheterogenität bedingen die größte Streuung der Ergebnisswerte und ein Ansatz, mit dem Ziel die Vergleichbarkeit zu erhöhen, wurde formuliert. Um die Subjektivität der spektralen Auswertung zu veringern, wurde das ’IFORS’ (Iterative Fitting Of Raman Spectra) Programm geschrieben, das die automatische, Benutzer-unabhängige Auswertung von Raman-Spektren ermöglicht. Um die Streuung aufgrund des verwendeten Messsystems zu reduzieren, wurde ein Referenzprobensatz zusammengestellt, der einen Temperaturbereich von 160 °C bis 600 °C abdeckt. Während der Probenaufbereitung wurde Resonanz-Raman- Spektroskopie mit mehreren Anregungswellenlängen an dispersen Vitriniten durchgeführt, die diagenetische bis epizonale Druck- und Temperaturbedingungen erfahren hatten, um die Gleichwertigkeit der RSCM-Methode und Vitrinitreflexion zu ermitteln. Mit Hilfe des IFORS Programms wurde der ’scaled total area’ (STA) Raman Parameter ermittelt, der das Raman Spektrum von kohligem Material präzise beschreibt. Auf Grundlage der Resonanz-Raman Daten konnte gezeigt werden, dass die Methodiken der STA-Raman Spektroskopie und Vitrinitreflexion analog zueinander sind, dass die STA-RSCM Methode gegenüber der Probenaufbereitung, insbesondere dem Polieren, robust ist, und dass die Resonanz-Raman Spektren der Vitrinite eine zweistufige molekulare Entwicklung während der Inkohlung und Graphitisierung aufzeichnen. Während der ersten Stufe, die kurz nach dem Durchschreiten des Gas-Fensters endet, wachsen vor allem lineare, polyzyklische, aromatische Kohlenwasserstoffe, während in der anschließenden zweiten Stufe kondensierte Formen von polyzyklischen, aromatischen Kohlenwasserstoffen wachsen. Um die Raman Spektren von metamorphem, kohligem Material zu beschreiben, wurde die STA-RSCM Methodik erweitert und erfolgreich gegen die Temperaturinformation des Referenzprobensatzes kalibriert, so dass ein neues, überarbeitetes RSCM-Geothermometer vorgestellt werden konnte, das über einen Temperaturbereich von 160°C bis 600°C zulässig ist. Der Referenzprobensatz steht öffentlich zur Verfügung und es wird erwartet, dass der Probensatz verbessert werden kann, wenn er um Proben aus der wissenschaftilchen Gemeinschaft erweitert wird. Wenn beide Ansätze, die STA-RSCM Methodik und der Referenzprobensatz, miteinander kombiniert werden, erhöht sich die Vergleichbarkeit zwischen den Laboren und gleichzeitig steht diese geothermometrische Methode allen Laboren zur Verfügung.

Made available in DSpace on 2016-08-19T12:56:47Z (GMT). No. of bitstreams: 1 Dissertacao MARCOS MOURA SILVA.pdf: 1156096 bytes, checksum: fba27f9f64081930b5c5d7149906ff4e (MD5) Previous issue date: 2014-03-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The use of certified reference materials is an alternative that laboratories have to ensure the quality of their analyzes. Many laboratories have been investing in the production of their own reference materials in-house. This study presents the application of an interlaboratory test on the certification of Fe, Ca, Si, Ni, Na, P and V in a sample of carbon electrodes candidate reference material in-house, from an aluminum industry in Brazil. The sample was crushed, milled and quartered. Subsequently, the material was filled into 128 botlles. Homogeneity tests were conducted on material that testified that the material remained homogeneous after preparation and stable over time of study. The material certification was made through a collaborative program which included the participation of seven laboratories in different locations. After applying the Cochran and Grubbs tests the values provided by laboratories certified values in ppm were: 589.08 ± 25.28 for Fe, 142.89 ± 12.03 for Ca; 332.03 ± 20.55 to V, 178.07 ± 9.26 for Ni, 326.11 ± 24.07 for Na; 134.17 ± 6.59 for Si and 7.38 ± 1.97 for P. Finally, the laboratories were compared using the z-score test and was observed satisfactory performance, except for the the laboratory 1 for Si analysis, which showed discrepant deviation of the others. The application of variance analysis led to the conclusion that the material was homogeneous and stable enough to be used as a reference material for quality control procedure. / O uso de materiais de referências certificados é uma alternativa que os laboratórios têm para garantir a qualidade de suas análises, razão pela qual muitos deles vêm investindo na produção de seus próprios materiais de referências in-house. Este trabalho apresenta aplicação de um ensaio interlaboratorial na certificação de Fe, Ca, Si, Ni, Na, P e V em uma amostra de eletrodos de carbono, candidata a material de referência in-house, de uma indústria de alumínio no Brasil. Amostras britadas, moídas e quarteadas foram envasadas em 128 frascos. Testes de homogeneidade e estabilidade atestaram que o material manteve-se homogêneo após o envase e estável na sua composição ao longo do tempo de estudo. A certificação do material se deu através de um programa de interlaboratorial que contou com a participação de sete laboratórios em diferentes locais. Após a aplicação dos testes de Cochran e Grubbs aos valores fornecidos pelos laboratórios, os valores certificados em ppm foram: 589,08 ± 25,28 para Fe; 142,89 ± 12,03 para Ca; 332,03 ± 20,55 para V; 178,07 ± 9,26 para Ni; 326,11 ± 24,07 para Na; 134,17 ± 6,59 para Si e 7,38 ± 1,97 para o P. Por fim, os laboratórios foram comparados por meio do teste z-score e observou-se desempenho satisfatório, exceto para o laboratório 1, nas análises de Si, que apresentou desvio discrepante dos demais A aplicação da análise de variâncias aos valores reportados levou a conclusão de que o material era homogêneo e estável o suficiente para ser usado como um material de referência para controle de qualidade interno.

Soot is a carbonaceous materials produced as a result of incomplete combustion of fuels (gasoline, diesel, etc). At the present level of automobile technology, emission of soot from combustion in diesel engine appears to be an inevitability. The disadvantage in the diesel combustion is that it is not homogeneous throughout the cylinder. So the fuel-air ratio cannot be maintained constant throughout the flame zone and hence rich combustion zone leads to the formation of soot. Diesel engine combustion processes produce a large amount of soot, which is one of the major pollutant emissions of the exhaust systems. The fraction of combustion particulate, which is soot, is often estimated by finding the insoluble portion of the particulate. Hydrocarbons or other available molecules may also condense on or beads orbed by soot depending on the surrounding conditions. Other particulate matter constituents include partially burned fuel/lubricant oil bound water, wear metal and fuel derived sulfate. In diesel engine lubrication, soot has long been recognized as the major contaminant that is detrimental to engine lubrication, particularly in friction and wear. Different techniques for soot abatement have been investigated by researchers from the field of combustion and fuel. In spite of the large numbers of investigations of soot formation conducted till date, there is relatively little quantitative information is available about the mechanisms and governing rate processes. Some of the studies focused on the combustion chemistry of soot formation while some emphasized on engine design. On the other hand comparatively a few research works are coming out from the tribological point of view. Considering that internal combustion engines play such an important role in industry, investigative research of the parametric influences of particle size, agglomeration, oil viscosity, additives and surfactant as well as chemistry and electrical properties of particles on wear as well as into the wear mechanisms have not perhaps been as extensive as it is detrimental. Existence of a large numbers of variables in tribological contacts makes the situation very complex and difficult to analyze it quantitatively. In this complex scenario, where many opposed effects are playing their roles in soot tribology, the influence of the physical, structural and mechanical properties of soot on engine tribology has limited attention. We focus our study on one of the end effects of engine soot; friction and wear of the engine components. Since a diesel engine is not particularly suitable for use in a laboratory study of the fundamental processes and parameters of combustion due to its inherent difficulties on control and safety as well as data analysis uncertainty, so the most useful studies of soot fundamentals have emerged from studies of processes which have used simplified environments such as diffusion flames. We focus on soot tribology in steel-on-steel interaction in the presence of soot material suspended in relatively simple paraffinic hydrocarbons, hexadecane; with and without an additive. The physical, structural, chemical and mechanical properties of the particle and their changes as a function of tribological parameters are monitored throughout this study. Three type of soot are used in this work. Firstly, commercial grade carbon blacks has been used as soot simulant. Secondly, to enable controlled variations of the physical, mechanical, chemical and geometrical parameters of the particles, soot is generated in-situ by burning ethylene gas and the particles are extracted thermophoretically from different thermal zones of the flame. Thirdly, to establish the validity of the study, two types of diesel soots are extracted from an engine and studied. The objective is to use such an understanding to elucidate the basic mechanisms of friction and wear in the presence of soot which may limit the performance of a diesel engine. From our study we find that these soots have widely different morphologies, crystallographic orders and reactivity. At tribological contact the soot agglomerates fragment to primary level particles. The physical and chemical properties of such particles determine the friction between and wear of mating components. If the soot is strongly graphitic, the friction and wear are moderate. If the soot is made of chemically active organic groups, the friction and wear are high. The hardness, friction and resistance to material removal of the soot collected near the flame tip and diesel soot are found to be high compared to the other types of soot. Besides, the high hardness, irregular primary particle shape, large inter-particle adhesion leading to agglomeration and more abrasive nature of diesel soot influence the metal wear adversely. This trend of soot tribology is profound when these soots are suitably dispersed in the oil by the addition of dispersants, in our case it is polyisobutylene succinimide. Different functional groups present on the soot surface play important role in defining the interaction between surrounding medium and contacts which, in turn define the contact conditions, particle/agglomerate behavior and soot tribology. Finally, agglomeration is simulated using the features of a dissipative particle dynamics package as the simulation technique. Simulations are performed on a sizeable number of particles to observe agglomeration behavior, on simple environment, in future which can be further extended.

No / The ESA/Roscosmos ExoMars rover will be launched in 2018. The primary aim of the mission will be to find evidence of extinct or extant life by extracting samples from the subsurface of Mars. The rover will incorporate a drill that is capable of extracting cores from depths of up to 2 m, a Sample Preparation and Distribution System (SPDS) that will crush the core into small grains and a suite of analytical instruments. A key component of the analytical suite will be the Raman Laser Spectrometer (RLS) that will be used to probe the molecular and mineralogical composition of the samples. In this work we consider the capability of the proposed Raman spectrometer to detect reduced carbon (possibly associated with evidence for extinct life) and to identify the level of thermal alteration/maturity. The Raman analysis of 21 natural samples of shale (originating from regions exhibiting different levels of thermal maturity) is described and it is shown that reduced carbon levels as low as 0.08% can be readily detected. It is also demonstrated that the Raman spectra obtained with the instrument can be used to distinguish between samples exhibiting high and low levels of thermal maturity and that reduced carbon can be detected in samples exposed to significant levels of oxidation (as expected on the surface of Mars). (C) 2014 Published by Elsevier Ltd.

Cette thèse est centrée sur la ceinture orogénique Attico-Cycladique formée durant l'orogénèse Alpine. Par une approche multi-méthodes et multi-échelles combinant géologie structurale, pétrographie, thermobarométrie des assemblages minéraux, géochimie élémentaire et isotopique, et données PVTX des inclusions fluides associées, ce travail vise à caractériser et comprendre les relations entre circulations fluides, interactions fluides/roches, déformation, et mobilisation-transport-dépôt des métaux. Les marbres et schistes de la péninsule du Lavrion et de l'île d'Eubée témoignent d'une évolution orogénique complexe marquée par une phase d'enfouissement à l'Eocène suivie par deux phases d'exhumation successives syn-et post-orogéniques. Les minéralisations de type Cu-Pb-Zn-Fe-Ag de la région du Lavrion sont synchrones de l’activation du détachement post-orogénique et de la mise en place de plutons de granodiorite. Leurs positions structurales témoignent d’un piégeage depuis un régime de déformation ductile jusqu'à fragile. Les minéralisations mises en place durant le régime de déformation ductile à ductile-fragile (skarn et remplacement de carbonate) sont associées à la décarbonatation des niveaux de marbres et à la circulation des fluides magmatiques. L'exhumation progressive de la racine orogénique se traduit par la transition des roches depuis une déformation ductile vers un régime fragile associé à l’ouverture du système aux fluides de surface et notamment aux fluides météoriques. Cette circulation est responsable d’une remobilisation des métaux des minéralisations primaires permettant alors une seconde phase de précipitation dans un régime cassant (veines épithermales) / This thesis is focused on the Attico-Cycladic orogenic wedge formed during the Alpine orogeny. From a multi-method and multi-scale approach using structural geology, petrography, mineral thermobarometry, element and isotope geochemistry, and PVTX data of associated fluid inclusions, this study deciphers the relationships between fluid circulation, fluid-rock interactions and mobilisation-transport-deposits of metals. Marbles and schists from the Evia Island and the Lavrion peninsula testify to a complex orogenic history marked by an Eocene burial phase followed by syn- and post-orogenic exhumation. Cu-Pb-Zn-Fe-Ag mineralisations from the Lavrion area are synchronous with the formation of the low-angle post-orogenic detachment and the emplacement of granodioritic magmas. The structural position of the deposits attests of an emplacement during ductile to brittle deformation conditions. Deposits associated with ductile to ductile-brittle deformation (skarn, carbonate replacement) are related to a marble decarbonation and magmatic fluid circulation. The progressive exhumation of the orogenic wedge allows the transition toward brittle conditions and opens the system to surficial meteoritic fluids. This meteoritic fluid circulation is responsible to remobilisation of metals from primary deposits allowing thus a second phase of deposition in a pure brittle deformation (epithermal veins)

Le bassin de Jaca (Pyrénées espagnoles) est un exemple classique de bassins d’avant pays, où les grandes lignes du remplissage sédimentaire, ainsi que la chronologie des failles ont été très étudiées. Il reste toutefois à mieux comprendre la paléo-hydrologie et l’histoire thermique du bassin, de manière à proposer un modèle de circulation des fluides pendant sa mise en place et sa déformation (Paléocène-Oligocène). Pour ce faire, ce travail propose d’analyser la répartition de la fracturation, d’étudier les conditions de formation des veines syn-tectoniques et de caractériser la maturité de la matière organique sur l’ensemble du paléobassin d’avant-pays de Jaca, des zones internes vers les zones externes.L’analyse pétrographique, géochimique et microthermométrique des veines montre que la grande majorité des fluides minéralisateurs sont à l’équilibre isotopique et thermique avec l’encaissant. Dans le détail, nous avons identifié 2 événements principaux de formation de veines dans la zone interne du bassin (Sierras Interiores), que nous proposons d’associer au fonctionnement des failles majeures dans le socle. Nous suggérons que les fluides circulent le long des niveaux de décollements et sont expulsés sur de courtes distances (< 10 km), au travers des réseaux de fractures, vers le bassin d’avant-pays. Le reste du bassin enregistre principalement des fluides locaux, parfois associés à l’infiltration d’eau météorique. L’analyse des températures d’enfouissement (50°C à 250°C), qui inclut des données de Δ47, montre une organisation N-S relativement homogène depuis les Sierras Interiores (fenêtre à gaz) jusqu’aux Sierras Exteriores (immature), avec des anomalies longitudinales marquées. Les modélisations thermiques 1D sur 9 puits virtuels suggèrent que les températures maximales vers les Sierras Interiores peuvent résulter d’un enfouissement sédimentaire, dont une grande partie est érodée actuellement. Nous proposons que ces parties érodées correspondent à des dépôts tardi-orogéniques conglomératiques déposés à proximité de la zone axiale. Les données suggèrent une répartition non homogène de ces dépôts selon un axe E-W, impliquant des transferts sédimentaires plus complexes qu’habituellement discutés. Au vu de nos résultats et des précédentes études, le modèle paléohydrologique et thermique du bassin de Jaca, et à plus grande échelle, de la chaîne plissée sud-pyrénéenne, est compartimenté à la fois dans l’espace et dans le temps, en lien avec à la propagation latérale et frontale de la déformation, qui contrôle l’ouverture du système. Le modèle paléohydrologique et thermique de la chaîne plissée sud-pyrénéenne constitue donc un potentiel analogue aux chaînes plissées dont le raccourcissement résulte d’une convergence oblique. / The Jaca basin (Spanish Pyrenees) is a classical example of a foreland basin, where the sedimentary filling and the calendar of thrust activation have been extensively studied. It remains to understand the paleohydrology and the thermal history of the basin, so as to provide a fluid flow model related to its formation and deformation (Paleoecene-Oligocene). To do this, this work proposes to analyze the distribution of fracturing, to study the conditions of formation of syn-tectonic veins and to characterize the maturity of organic matter throughout the Jaca foreland basin, from hinterland to external areas.Petrographical, geochemical and microthermometric analysis of veins show that the vast majority of mineralizing fluids are at the isotopic and thermal equilibrium with the host-rock. In detail, we identified two main events of vein precipitation in the inner part of the basin (Sierras Interiores), probably related to major basement thrust activations. We suggest that fluids flow along decollement levels and are expelled over short distances (<10 km), through fracture networks towards the foreland basin. The other part of the basin mainly record local fluids, sometimes associated with the infiltration of meteoric water. Analysis of burial temperatures (50 °C to 250 °C), which includes Δ47 data, shows a relatively homogeneous N-S organization from the Sierras Interiores (gas window) to Sierras Exteriores (immature), with strong longitudinal anomalies. Thermal 1D modelling of 9 virtual wells suggest that the maximum temperatures of Sierras Interiores result from sedimentary accumulation, whose a large amount is now eroded. We propose that this eroded thickness corresponds to late-orogenic conglomeratic deposits near the axial zone. The data suggest an inhomogeneous distribution of the deposits along an E-W axis, involving more complex sedimentary transfers than usually discussed. Given our results and previous studies, the paleohydrological and thermal model of the Jaca basin, and on a larger scale, of the South Pyrenean fold and thrust belt, is compartmentalized both in space and in time, in response to the propagation of and oblique deformational front, which controls the opening of the system. The paleohydrological and thermal model of the South Pyrenean fold and thrust belt is therefore a potential analogue to fold and thrust belt including shortening due to an oblique convergence.