Dissertations / Theses on the topic 'Asphaltene'

<p>Crude oil is the primary source for energy in the world and serves as the raw material for many daily products. Two topics, important in the daily processing of crude oils, are treated in this thesis. Water-in-oil emulsions must be broken to obtain the desired quality of the crude oil delivered to the refineries with respect to water and salt content and asphaltenes are of concern at all stages of the recovery, transportation and processing of crude oils. The work has been of experimental nature and the results are reported in journal papers and manuscripts.</p><p>A lab-scale continuous separation rig was constructed and later equipped with a compact electro coalescer. The results show that water cut and pressure drop affect the droplet size distribution of water-in-oil emulsions. Moreover, two demulsifiers were tested on crude oil emulsions under high electric fields. The study indicated that it is not trivial which type of demulsifier to choose when an electric field is applied in combination with chemical destabilization.</p><p>Hansen solubility parameters for solvents and binary mixtures were correlated to infrared and near infrared spectra by partial least squares regression. Regression coefficients and errors of validation indicated that the regressions and predictions were good. The models were used to predict solubility parameters for crude oils and SARA fractions and the values obtained were in range of what has been reported in the literature.</p><p>Asphaltenes were separated into several solubility fractions directly from the crude oil by stepwise addition and precipitation by n-pentane. The solubility fractions had very different properties with regard to aggregation onset and interfacial activity which to a certain degree were explained by the differences found in the average size and molecular structures of the fractions. It was shown that the less soluble fractions consisted of molecules with larger average molecular weight, higher aromaticity and more polar aromatic cores. For the more soluble fractions results indicated that the substituted alkyl side chains on the aromatic cores were more branched and contained more of the hydroxylic and carboxylic groups, which again could explain the higher interfacial activity. Experiments also suggested that neither the least nor the most soluble of the asphaltenes under investigation were the ones with the highest interfacial activity, but a middle fraction. The findings suggest the need for looking into solubility fractions of asphaltene in further research and compare with the asphaltenes found in deposits or obtained from pressure drop experiments.</p>

Le colloïde asphalténique est une espèce multifonctionnelle composée de quatre types de sous‐fractions : deux fractions dénommées « A1 » et « A2 », les résines et les composés piégés (CP). La composition du colloïde détermine sa solubilité donc son paramètre de solubilité. Si on enlève une des sous fractions, le paramètre de solubilité change ainsi que la solubilité de la particule résultante. Le colloïde peut être considéré comme une solution avec valeurs de RED (différence d'énergie relative, selon l'acronyme en anglais) inférieures à 1 entre tous les composants séparés et avec un paramètre de solubilité global égale à la résultante des paramètres de solubilité des quatre composantes. Nous pouvons distinguer trois types d'interactions principales qui donnent lieu à la formation de ces colloïdes : les forces de dispersion, les interactions polaires et la formation de ponts hydrogène. Ces interactions conduisent à des énergies libres de formation très élevées en valeur absolue, ce qui limite significativement leur capacité de dissociation sous l'effet de la température ou de la polarité du dispersant. Même à des températures très élevées, la formation d'agrégats en milieu dispersant polaire ou non polaire est observée. Les composés piégés (CP) sont des espèces solubles dans l'heptane. Ils sont différents des asphaltènes et des résines. Ils restent piégés dans la structure du colloïde. Les CP sont constitués par plusieurs types de composés qui ont la capacité de s'associer aux asphaltènes par des forces dispersives ou des interactions polaires faibles. Parmi ces composés, nous pouvons nommer les pétroporphyrines métalliques (PPM) de vanadium et de nickel. Ces structures restent masquées dans la matrice moléculaire de l'agrégat asphalténique. Sa libération dépend de la dissociation totale ou partielle du colloïde, laquelle est fortement limitée par la constante d'agrégation très élevée. En outre, les CP établissent des liaisons dans la périphérie du colloïde qui sont relativement faibles par rapport à celles existantes entre les asphaltènes. Quand sous l'effet de la température ou d'autres changements physico‐chimiques, les CP sont enlevés de la périphérie du colloïde, l'association entre eux est favorisée, ce qui donne lieu à la formation de conglomérats. La diminution du paramètre de solubilité et du point de fusion des asphaltènes sont les effets primordiaux des résines associées au colloïde asphalténique ; tous les deux contribuent à l'augmentation de la solubilité des asphaltènes dans le pétrole brut, car la pénétration de ce dernier dans la périphérie colloïdale est favorisée. Pour la détermination du paramètre de solubilité (PS), nous avons utilisé via le logiciel sphère l'équation développée par Hansen en utilisant 61 dispersants différents. A partir des études de solubilité, nous avons obtenu les composantes correspondantes aux interactions moléculaires de dispersion (δD), polaires (δP) et ponts hydrogène (δH) exprimées en Mpa ½. Les résultats sont en accord avec toutes les propriétés de solubilité connues des asphaltènes et ont confirmé la solubilité plus faible de la sousfraction A1 par rapport à la fraction A2, avec tous les solvants employés. A partir de cette méthode, nous avons pu également confirmer la forte affinité qui existe entre les asphaltènes et les sous‐fractions A1 et A2 avec les porphyrines métalliques. La valeur plus élevée de la composante correspondant aux ponts hydrogène obtenue pour la fraction A1 suggère la capacité plus forte de celle‐ci pour former ce type de liaisons. Les échantillons (AsfB, A1 et A2) ont été analysés en employant une technique de chromatographie par perméation de gel couplée à un spectromètre de masse à plasma à couplage inductif (GPC‐ICP‐MS). L'objectif de cette étude était d'identifier les mécanismes de capture des PPM par les asphaltènes par comparaison de profils chromatographiques [etc...]<br>El coloide asfalténico es un cuerpo multifuncional constituido por cuatro clases de subfracciones conocidas como A1, A2, resinas y compuestos atrapados (CA). La composición del cuerpo o partícula coloidal determina su solubilidad o parámetro de solubilidad, de tal forma, que la remoción de cualquiera de sus componentes cambia dicho parámetro y por ende la solubilidad del resto. El coloide, es así una disolución con valores de RED (Diferencia de Energía Relativa, por sus siglas en inglés) inferiores a 1 entre todos sus componentes por separado y con un parámetro de solubilidad global igual a la resultante de los parámetros de solubilidad de cada componente. Pueden distinguirse tres tipos de interacciones principales, que dan lugar a la formación del agregado las cuales son, dispersión, polar y puente de hidrógeno. Estas interacciones actúan en conjunto proporcionando energías libres de formación muy altas en valor absoluto, lo cual limita significativamente su capacidad de disociación por medios tales como temperatura y polaridad del disolvente; formando de esta manera, agregados en disolventes polares y no polares, incluso a temperaturas muy altas. Los CA son compuestos solubles en heptano, que sin ser asfaltenos o resinas quedan atrapados dentro del coloide, ellos están constituidos por muchas clases de compuestos con capacidad para asociarse a los asfaltenos de varias maneras, como enlaces de dispersión y de baja polaridad. Entre muchos otros compuestos, las petroporfirinas metálicas (PPM) de vanadilo y níquel forman parte de estos CA, ellas quedan ocluidas en el entramado molecular del agregado asfalténico. Su liberación depende de la disociación total o parcial del coloide la cual es obstaculizada por la alta constante de agregación. Además de su captura “mecánica” en el laberinto molecular del coloide, los CA se asocian en la periferia coloidal mediante enlaces relativamente débiles en comparación con aquellos que existen entre asfaltenos. Cuando por efecto de la temperatura u otro cambio fisicoquímico, los CA son removidos de la periferia del coloide, se promueve la asociación entre ellos dando lugar a conglomerados. La reducción tanto del parámetro de solubilidad, como del punto de fusión de los asfaltenos son los efectos primordiales de las resinas asociadas al coloide asfáltico; ambos contribuyen a incrementar su solubilidad en el crudo, pues facilitan la penetración del medio en la periferia coloidal. Para la determinación del parámetro de solubilidad (PS) se aplicó el método Sphere desarrollado por Hansen, empleando 61 disolventes distintos, a partir de los cuales se obtuvieron las componentes correspondientes a las interacciones moleculares de dispersión (δD), polares (δP) y las de puente de hidrógeno (δH) en Mpa ½. El método fue consistente con todas las propiedades de solubilidad conocidas del asfalteno y confirmó la menor solubilidad de la subfracción A1 con respecto a la subfracción A2, en todos los solventes ensayados. Mediante el método también se predijo la gran afinidad que existe entre los asfaltenos, las subfracciones A1 y A2 con las porfirinas metálicas. El mayor valor obtenido para A1 en la componente de puente de hidrógeno, hace presumir la mayor capacidad que posee esta fracción en formar enlaces tipo puente de hidrógeno [etc...]

<p> Petroleum asphaltenes (n-heptane insolubles and toluene solubles) and fractions more and less soluble in mixtures of heptane and toluene (heptol) were analyzed chemically and by small angle neutron scattering (SANS). Asphaltene chemistry and their propensity to aggregate in solution were correlated to the stability of water-in-oil emulsions and the strength of adsorbed films at oil-water interfaces. Solubility profiles of the more soluble and less soluble fractions in heptol indicated strong cooperative asphaltene interactions. The less soluble asphaltene fractions had lower H/C ratios, higher N, V, Ni, and Fe contents than the more soluble or unfractionated asphaltenes. Neutron scattering studies at 25 and 80°C indicated asphaltenes near their solubility limit formed the largest aggregates. Highly aromatic solvents and the presence of petroleum resins disrupted intermolecular pi and hydrogen bonding and reduced the degree of aggregation. Less soluble fractions formed aggregates considerably larger than the unfractionated asphaltenes (as high as 520 Å), while soluble asphaltenes formed the smallest aggregates (as low as 22 Å). Enhanced aromatic pi-pi bonding, dispersion forces and hydrogen bond interactions within the less soluble fraction likely caused large aggregate formation and low solubility. Emulsion stability was gauged by the volume percentage of water resolved after centrifugation at high speed (15,000 rpm). Strong emulsion formers were characterized by intermediate to large aggregates with lower aromaticity and higher nitrogen polarity, Ni and V. Asphaltenes aggregating due primarily to H-bonding and by pi-pi interactions were presumed to form a cohesive interfacial oil-water film and stable emulsions. At low aromaticities (< 30 % toluene), asphaltenes were poorly solvated without resins and did not form stable emulsions. Increasing the resin-asphaltene ratio to 5 or 10:1 of the less soluble asphaltene fractions significantly enhanced emulsion stability (< 20 vol % water resolved). Higher R/A (> 20) led to emulsions with partial stability (40-80 % water resolved). A biconical bob interfacial shear rheometer was used to study the properties of asphaltene films at oil-water interfaces. The degree of film consolidation was determined from ratios of elasticity (G')/film mass and yield stress/G'. Asphaltenes with higher concentrations of heavy metals (Ni: 330-360 ppm, V: 950-1000 ppm), lower aromaticity (H/C: 1.24-1.29), and higher polarity (N: 1.87-1.99) formed films of high elasticity, yield stress and consolidation. <P>

Aggregation of asphaltenes has attracted interest due to the impact on the crude-oil industry. Despite extensive studies on the molecular-structure of natural asphaltene, fundamental knowledge of their aggregation is incomplete. It is unclear how the driving forces of association are related to the molecular architecture and the solvent species, which ultimately affect the aggregation mechanism. In this dissertation, dynamic-light-scattering (DLS) experiments and molecular-dynamics (MD) simulations were performed to investigate the relation between asphaltene chemical-structure and solvent species. The model compounds studied isolate the driving forces of aggregation by varying the peripheral chain-length and functional-groups (triphenylene-cored models) in organic solvents. The results isolate the structure-function relationships. Increasing the chain length imposes restriction upon the nanoaggregate formation, while non-centrosymmetric models appear to be more prone to aggregation. Furthermore, polar components in asphaltene molecular-architecture are observed to increase aggregation potential, more than π-stacking. Hexabenzocoronene-cored models exhibit a structurally selective aggregation mechanisms, as the planar molecules are more liable to aggregate and precipitate than the non-planar models due to π-stacking hindrance. The motivation behind the development and testing of model polyaromatic compounds lies in the pursuit of isolating the source structural-dependence of the compounds interactions. This is done by assessing the solute-solute and solute-solvent associations by experimental and computational approaches, to underpin the structure-to-function relation dictated by aromatic and/or polar molecules in aromatic or aliphatic solvents. This dissertation provides insight for the aggregation of model compounds of varying molecular architectures, and sheds light on the intermolecular interactions affected by these variations and the solvent species.

A novel approach to asphaltenes precipitation and deposition prediction and forecast, applied multiple methods including innovative numerical modeling within multiphase flow. Furthermore, modeled the effect of CO2 injection on asphaltenes precipitation during enhanced oil recovery within the reservoir and wellbore. The parametric effect on asphaltenes deposition of crude oil was modeled and evaluated against previous experimental values. The numerical models and simulations were in good agreement with the steady-state solution of the asphaltenes onset curve.

La croissance de la demande en produits pétroliers (essence et gazole), en particulier dans les pays développés, et la nature limitée des ressources pétrolières conduisent l’industrie pétrolière à s’intéresser de plus en plus à l’exploitation et la transformation des huiles lourdes et extra-lourdes. Leurs propriétés non conventionnelles du fait de leur forte composition en asphaltènes (particules définies comme l'ensemble de constituants insolubles dans le n-heptane et solubles dans le toluène) nécessitent la mise en oeuvre de procédés de plus en plus sophistiqués à toutes les étapes de leur exploitation et de leur production. Ces bruts, situés principalement au Canada et au Venezuela, sont caractérisés par leur forte viscosité de 1 à 55 Pa.s (1 000 cP à 55 000 cP), qui rend leur transport en surface impossible dans leur état naturel. Le développement de solutions technologiques nouvelles repose sur une meilleure connaissance des propriétés thermo- physiques et du comportement colloïdal de ces produits.Les méthodes de caractérisation expérimentale et de modélisation utilisées pour les bruts conventionnels sont inadaptées pour les bruts lourds et extra lourds. La caractérisation PVT des bruts lourds fait l’objet de nombreux travaux à l’heure actuelle. Les propriétés à déterminer sont les équilibres de phase et les propriétés thermo physiques des phases en équilibre. Dans ce contexte, cette thèse a pour objectifs principaux le développement de méthodes expérimentales et de modèles adaptés aux bruts lourds et aux procédés de récupération envisagés pour ces bruts (production froide, injection de solvant VAPEX, injection de vapeur SAGD, etc...)<br>Due to increasing demand for fuel, in particular for developed countries, and the limited nature of reserves, petroleum industry is, and will, growing concerned by the heavy and and extra-heavy oil processing. The non-conventional properties of these oils (due to a high asphaltene composition) require specific engineering solutions during the different steps of their processing. These crudes, mainly localized in Canada and Venezuela, are characterized by their strong viscosity, from 1 up to 55 Pa.s, which makes their transport to earth surface impossible. The development of new technological solutions is based on a better knowledge of the thermophysical properties and the colloidal behavior of these products. The methods of experimental characterization and modelling used for the conventional crudes are unsuited for both heavy and extra heavy crudes. To date, characterization PVT of heavy crudes is the subject of numerous studies. The properties to be determined are balances of phase and thermophysical properties of the equilibrium cycles. In this context, the main objectives of this thesis are not only the development of experimental methods and models suitable for heavy crudes, but also the recovery processes envisaged for these crudes (cold production, VAPEX process, SAGD process, etc…)

Microfluidic H-cells and surface enhanced Raman spectroscopy are capable of analysing the asphaltene content of petroleum. An H-cell is a microfluidic device that exploits the non-turbulent flow of fluids within a micrometre-dimensioned channel. Diffusive separation in an H-cell permits a liquid that is miscible with the sample matrix to be used as an extractant. It was demonstrated that n-hexane can be used as extractant to obtain an asphaltene-free fraction of oil. The difference between the UV-Vis adsorption spectra of the asphaltene-free oil and the oil sample can then be used to estimate its asphaltene content. This has been demonstrated for a range of oils with asphaltene content between 1-30% and API gravity values between 40-10°, thus liquid petroleum and bitumen can be rapidly assayed by an H-cell; similarly, asphaltene and carboxylic acid content of oil can be determined simultaneously when methanol is used as extractant. The results were shown to be comparable to assays achieved via the ASTM D4124 and ASTM D974 methods respectively. For the first time it was demonstrated that surface enhanced Raman spectroscopy, using a gold substrate and illumination at 514 nm, can detect extremely low concentrations of asphaltene. This was shown to be achievable for asphaltene and related materials at concentrations of 0.001 ppm. In addition, data also demonstrated that the core of the Raman-responsive units within asphaltene have crystallite sizes equivalent to the Raman-responsive units in kerogen (~3 nm). Both methods provide technological advances because they make it possible to detect asphaltene in small sample volumes, using smaller footprint instrumentation. The H-cell method would be extremely useful for appraising oilfield potential, record the attenuation of oil-spills and provide frequent geochemical data that can monitor these at point of need. Similarly, the SERS technique widens the field of application into areas previously inaccessible to current techniques such as the effect of low concentrations of asphaltene-like materials in ecological and living systems.

L’objectif de ce travail est de proposer à l'industrie pétrolière un modèle thermodynamique compositionnel capable de prévoir les conditions opératoires induisant la floculation des asphaltènes à partir des bruts. Au cours de cette étude, diverses méthodes d'analyse (calorimétrie, analyse élémentaire, RMN du 13C, diffusion des neutrons…) ont été utilisées afin d'acquérir une meilleure description de la fraction asphalténique et d'en déduire les mécanismes de sa floculation. Le modèle proposé décrit cette floculation comme une transition thermodynamique induisant la formation d'une nouvelle phase liquide riche en asphaltènes et contenant l'ensemble des constituants initialement présents dans le brut : le dépôt asphalténique. Les asphaltènes sont représentés à l'aide d'un seul pseudo-constituant composé essentiellement de carbone et d'hydrogène. La représentation de la fraction légère F11-F20 est celle proposée par Jaubert. La fraction lourde F20+ est représentée à l'aide de quatre pseudo-constituants, leurs propriétés caractéristiques étant déterminées à l'aide des méthodes de contribution de groupes développées par Avaullee ainsi que par Neau et Rogalski. L'équation d'état de Peng-Robinson associée aux règles de mélange par contribution de groupes d'Abdoul et Peneloux est utilisée afin de restituer les équilibres de phases gaz-liquide-dépôt asphalténique. Ce modèle ne permettant pas de restituer la floculation de façon purement prédictive, la démarche consiste alors à ajuster certaines propriétés caractéristiques des pseudo-constituants introduits dans la représentation analytique des bruts. Les résultats obtenus montrent que le modèle de floculation proposé est bien adapté à la restitution des propriétés thermodynamiques (pressions de saturation, volumes relatifs, courbes de floculation) des bruts asphalténiques sur un large domaine de températures (30-150°C) et de pressions (0,1-50 MPa), couvrant la majorité des cas rencontrés dans l'exploitation pétrolière

Asphaltenes are the heaviest and most complex components in crude oil. Their precipitation and deposition may cause severe problems during production, transportation and processing of crude oil, hence affecting efficiency and cost of production in both upstream and downstream operations. During crude oil production, asphaltenes can deposit in the pores of reservoir rocks resulting in formation damage. Despite significant research, asphaltene behaviour in different flow regimes remains elusive. This thesis presents an investigation into crude oil asphaltene precipitation and deposition at ambient and reservoir conditions, using different experimental techniques and multi-scale simulations. Asphaltene precipitation can be triggered by altering the crude oil composition, which has been studied here through filtration experiments; a useful method to determine the amount of asphaltene precipitation induced by any precipitant. The relationship between the mass of precipitated asphaltenes and the mass of a precipitant in a crude oil+hydrocarbon system was compared to a crude oil+CO2 mixture in high pressure-high temperature experiments under conditions where the assumption of full miscibility is not valid. The precipitation onset point for the heavy crude oil used throughout the study was precisely determined in terms of the Hildebrand solubility parameter, showing for the first time that CO2 follows the same behaviour as hydrocarbon precipitants. However, the solubility parameter was not suitable for correlating precipitation at different temperatures. Subsequently, this work reports on asphaltene deposition in glass capillary flow experiments under laminar conditions where asphaltenes were precipitated with n-heptane, an analogue fluid for CO2. This study elucidates the fundamental behaviour of asphaltene deposition through the unique combination of techniques not previously been illustrated in the literature. The experiments involved co-injecting a toluene diluted crude oil and n-heptane through a capillary at constant volumetric flow rate while simultaneously measuring the pressure drop across the capillary. Increasing the total volumetric flow rate led to more deposition, observed through confocal laser-scanning microscopy and mass measurements, with more deposits build up at the capillary inlet. Beyond a critical flow rate, the deposition rate decreased as entrainment effects became more profound. Deposition was limited as the pressure levelled off in all the experiments, and oscillations in pressure suggested dynamic cycles between deposition and entrainment. In addition, a dependence of deposition on the floc size was revealed, showing that smaller particles dominate the deposition process. The experimental results were then compared to stochastic rotation dynamics simulations at the colloid scale, where a constant pressure drop over the capillary length was imposed. Results show a more homogeneous deposition profile with higher Peclet number, which is in agreement with the experimental findings. Additionally, deposition studies were extended to real sandstone reservoir samples using C7 and CO2 as precipitants at more realistic reservoir conditions. Pressure drop measurements across the core to quantify permeability damage were combined with X-Ray Microtomography (microCT) to visualise the deposits produced within the porous medium. The permeability measured through core-flooding experiments was compared to lattice-Boltzmann calculations in the segmented microCT images before and after deposition, where an increase in the flow rate showed a decrease in dimensionless permeability. Fitting the pressure drop data to a computational Deep Bed Filtration model allowed for a distinction between pore surface and pore throat deposition, which was confirmed by the microCT images of the location of asphaltene deposits. The results elucidate important asphaltene-related issues in porous media and provide a suitable framework for developing and improving deposition models.

The vapour extraction process, or &amp<br>#8216<br>VAPEX&amp<br>#8217<br>has attracted a great deal of attention in recent years as a new method of heavy oil or bitumen recovery. The VAPEX (vapour extraction) can be visualized as energy efficient recovery process for unlocking the potential of high viscosity resources trapped in bituminous and heavy oil reservoirs. A total of 20 VAPEX experiments performed with Hele-Shaw cell utilizing three different Turkish crude oils. Two different VAPEX solvents (propane and butane) were used with three different injection rates (20, 40 and 80 ml/min). Garzan, Raman and Bati Raman crude oils were used as light, medium and heavy oil. Apart from normal Dry VAPEX experiments one experiment was conducted with CO2 and another one with butane + steam as Wet VAPEX experiment. All experiments were recorded by normal video camera in order to analyze visually also. For both VAPEX solvents, oil production rates increased with injection rates for all crude oils. Instantaneous asphaltene rate for Garzan oil, showed fluctuated performance with propane solvent. Butane showed almost constant degree of asphaltene precipitation. Instantaneous asphaltene rate for Raman and Bati Raman oils gave straight line results with the injection rate of 20 ml/min for both solvent. When the injection rate increased graphs showed the same performance with Garzan oil and started to fluctuate for both solvent. For asphaltene precipitation, propane gave better results than butane in almost all injection rates for Garzan and Raman oil. In the experiments with Bati Raman oil, butane made better upgrading than propane with the injection rate 80 ml/min. With the other two rates, both solvents showed almost same performace.

L'objectif de cette étude était de proposer des méthodes de caractérisation des bruts de pétrole qui apportent une information pertinente, permettant d'évaluer les risques de floculation des asphaltènes. Nous avons ainsi utilisé 4 techniques expérimentales notamment la densimétrie, la chromatographie inverse, granulométrie laser et la calorimétrie différentielle à balayage permettant la connaissance des propriétés structurales et thermodynamiques des fluides pétroliers. Nous avons proposé une nouvelle méthode de détermination du seuil de floculation des asphaltènes basée sur le changement de densité de fluide pétrolier entraîné par le phénomène de floculation. La chromatographie inverse a permis de déterminer le paramètre de solubilité de Hildebrand des fluides pétroliers et des asphaltènes d'une part et d'autre part leur caractérisation chimique à l'aide paramètre LSER. Les résultats obtenus par la calorimétrie et la granulométrie laser permettent de comprendre la variation de la structure colloïdale des fluides pétroliers avec la température et la composition<br>The objective of this study was to propose methods of characterization of the crude oils, making it possible to evaluating the risks of asphaltenes flocculation. With this view, we have used four experimental techniques: densimetry, inverse gas chromatography, dynamic light scattering and differential scanning calorimetry allowing to assess necessary thermodynamic and structural properties of crude oils. The firts two techniques brought a thermodynamic characterization of the crude oils, while following ones made it possible to characterize the structures of the crude oils and the aggregates asphaltenic. We have proposed a new method to determine asphaltenes flocculation onset based on the changes of the crude oils density implied by the flocculation process. Inverse chromatography allowed to determine the Hildebrand solubility parameter of crude oil and asphaltenes and to obtain the chemical characterization of them in terms of LSER paramters. Calorimetry and light scattering results gave valuable insight into variation of the colloidal structure of the crude oil with temperature and composition changes

Depuis 5 ans, l’autoémulsification de l’eau dans les bruts a été reportée sur plusieurs systèmes, et associée une récupération améliorée du pétrole. Nous avons tenté de comprendre quelle était son origine physico-chimique. Nous avons constaté que lorsqu’on mettait en contact du pétrole brut avec de l’eau, il se formait alors des micro-gouttes d’eau dans l’huile pour toutes les huiles lourdes étudiées. Nous avons montré que le phénomène d’émulsification spontanée observé lors du contact de pétrole brut avec de l’eau de faible salinité est un mécanisme doublement osmotique, régit par la double pénétration d’eau et des espèces « osmogènes » (ie espèces générant de la pression osmotique) dans les gouttelettes d’eau. Puis nous avons montré que le phénomène limitant est celui de la diffusion de l’eau dans l’huile et nous proposons une expression pour sa cinétique. En outre, nous avons observé deux phénomènes concomitants lors de l’étude de la récupération en huile à l’échelle microfluidique : récupération additionnelle d’huile et présence de micro-gouttes d’eau. Nous proposons d’expliquer cela par le gonflement des poches d’eau par le phénomène d’émulsification spontanée<br>Since 5 years, the autoemulsification of water in crude oils has been reported on several systems, and associated with improved oil recovery. We tried to understand what was its physicochemical origin. We found that when we put crude oil in contact with water, micro-droplets of water were formed in the oil for all the crude oils studied. We have shown that the phenomenon of spontaneous emulsification observed during the contact of crude oil with low salinity water is a double osmotic mechanism, governed by the double penetration of water and "osmogeneous" species (ie species generating osmotic pressure) in the water droplets. Then, we showed that the limiting phenomenon is the diffusion of water in the oil and we propose an expression for its kinetics. In addition, we observed two concomitant phenomena during the study of microfluidic scale oil recovery: additional oil recovery and the presence of micro-droplets of water. We propose to explain this by the swelling of the water pockets due to the phenomenon of spontaneous emulsification

Asfaltenos são constituídos de hidrocarbonetos policíclicos aromáticos que fazem parte de uma das classes de compostos químicos mais poluentes e carcinogênicos. São bem conhecidos por formarem inscrutações que obstruem tubulações, podendo até levar ao fechamento do poço. Estes podem constituir até 20% do petróleo, que ainda remanesce o principal recurso de energia usado em nosso planeta. Atualmente são convertidos em asfalto e coque durante o processo de refino, através de destilação destrutiva, exigindo altas temperaturas e emitindo compostos de enxofre na atmosfera. No entanto, sua conversão em matérias-primas mais valiosas e produtos menos poluentes, por exemplo, por craqueamento fotocatalítico ou oxidativo poderia ser uma opção mais limpa e econômica. A nanotecnologia vem sendo incorporada nas pesquisas com petróleo pelas contribuições positivas que acrescenta tanto do ponto de vista econômico como ambiental, assim como através do melhoramento e recuperação de óleos pesados. Os nanomateriais em geral possuem a vantagem de ter maior grau de dispersão e propriedades diferenciadas em relação ao bulk. Neste trabalho estudaram-se as interações entre os asfaltenos e diferentes nanomateriais com propriedades magnéticas, ópticas e eletrônicas extraordinárias, como as nanopartículas de óxido de ferro (Nmag), os híbridos de nanopartículas de ouro com óxido de grafeno reduzido (RGO@AuNP) e os nanobastões de ouro (AuNRs) respectivamente. As interações entre asfaltenos e Nmags com diferentes ligantes passivantes (C8H20O4Si e C6H17NO3Si) foram feitas através da construção de isotermas e experimentos de adsorção,revelando os tipos de ligação que ocorrem entre esses materiais, cobertura e a capacidade adsortiva. O recobrimento da nanopartícula e a concentração de asfalteno influenciam na adsorção, sendo a interação mais forte com as Nmags livres, indicando coordenação do ferro nos substituintes dos anéis aromáticos do asfalteno, tendo cobertura por monocamada. As Nmags funcionalizadas interagem por forças intermoleculares com os asfaltenos, apresentando cobertura por multicamadas. Em altas concentrações de asfalteno em tolueno, a adsorção foi mais efetiva para as Nmags funcionalizadas, pois a coordenação com o ferro é dificultada devido a formação de micela reversa, prevalecendo as interações hidrofóbicas. Houve uma drástica redução na temperatura de craqueamento dos asfaltenos na presença das Nmags, em mais de 100ºC, demonstrando seu potencial na catálise oxidativa de asfaltenos. As interações dos materiais RGO@AuNP e AuNR em filmes com asfalteno foram investigadas por microscopia hiperespectral de campo escuro. Como resultado observou-se o deslocamento e o alargamento da banda de espalhamento no espectro eletrônico, indicando a ocorrência de transferência de carga entre as espécies. A partir disso, realizaram-se fotocatálises com o RGO@AuNP à temperatura ambiente sob luz visível, utilizando o 9-antraldeído como composto modelo para o asfalteno. A reação levou à formação de endoperóxidos cíclicos, que sofreram clivagens com 90% de rendimento. Por ultimo, realizou-se um estudo mecanístico utilizando um sensor fluorogênico de espécies reativas de oxigênio (ROS) para avaliar a atividade fotocatalítica do RGO@AuNP. Mostrou-se que ocorrem transferências de elétrons fotoinduzidas da AuNP para o RGO em uma escala de tempo de ~11 fs, com eficiência quântica de ~35% e que radicais superóxidos (O2&#8226;-) podem ser gerados pelos efeitos sinérgicos da fotoexcitação do híbrido.<br>Asphaltenes are composed by polycyclic aromatic hydrocarbons that belong to one of the most polluting and carcinogenic chemical classes. They are well known for forming hard scales that obstruct pipelines and may even lead to the well shut down. They can constitute up to 20% of petroleum, which still remains the main source of energy used in our planet. At the present time, asphaltenes are converted into asphalt and coke by destructive distillation, in spite of the high cost and polluting technology involved, which employs high temperatures and releases sulfur compounds into the atmosphere. However, their conversion into more valuable raw materials, for instance, by photocatalytic or oxidative cracking using suitable catalysts, would be a better, more economic option. In recent years, nanotechnology has been incorporated into oil research, opening new economic and environmental perspectives, including the improvement and recovery of heavy oils. In general, nanomaterials have the advantage of being better dispersed and exhibiting differentiated properties in relation to the bulk. In this study the interactions between asphaltenes and different nanomaterials exhibiting remarkable magnetic, optical, and electronic properties, such as iron oxide nanoparticles (Nmag), hybrids of gold nanoparticles with reduced graphene oxide (RGO@AuNP) and the gold nanorods (AuNRs) respectively were investigated. The interactions between asphaltenes and Nmags with different surface-passivating ligands (C8H20O4Si and C6H17NO3Si) were made by performing isotherms curves and adsorption tests, revealing the types of binding between these materials, their coverage and the adsorptive capacity. The nanoparticle coating and the asphaltene concentration influence the adsorption. Theinteraction was stronger using the free Nmag, indicating coordination of the iron with the aromatic rings of the asphaltene, having a monolayer cover. Functionalized Nmags interact by intermolecular forces with asphaltenes, having a multilayer coverage. At high concentrations of asphaltene in toluene, the adsorption was more effective for the functionalized Nmags, since the coordination with the iron was hampered due to the formation of reverse micelle, prevailing the hydrophobic interactions. There was a drastic reduction in the asphaltene cracking temperature in the presence of Nmags, bigger than 100ºC, showing its potential on the oxidative catalysis of asphaltenes. The interactions of RGO@AuNP and AuNR materials with asphaltene films were investigated by dark field hyperspectral microscopy. As a result there was a shift and a broadening of the band in the electronic spectrum, indicating the occurrence of charge transfer between the species. From this, photocatalysis were performed with the RGO@AuNP, at room temperature, under visible light, using 9-antraldehyde (9-ATA) as a model compound for asphaltene. The reaction leads to the formation of cyclic endoperoxides that undergo further reactions, resulting in their cleavage, with 90% yield for the 9-ATA degradation. Finally, a mechanistic study was carried out using a fluorogenic sensor of reactive oxygen species to evaluate the photocatalytic activity of RGO@AuNP. It was showed that photoinduced electron transfer from AuNP to RGO can occur in ~11 fs time scale, with a quantum yield of ~35%, and superoxide radicals anions (O2&#8226;-) can be generated by synergistic effects after the hybrid photoexcitation.

Orientador: Maria Regina Wolf Maciel<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica<br>Made available in DSpace on 2018-08-15T01:50:27Z (GMT). No. of bitstreams: 1 RoccaRivarola_FlorenciaWisnivesky_M.pdf: 9147569 bytes, checksum: 2744b00d9edfcd31f6704d23a6fa772d (MD5) Previous issue date: 2009<br>Resumo: Os asfaltenos são macromoleculas aromáticas complexas, que apresentam estrutura que varia de acordo com o local de extração do óleo. Esta fração tem sido muito estudada pela indústria de petróleo, não apenas por sua contribuição às propriedades do óleo cru, mas também pelos problemas associados a sua agregação e precipitação. Com isso, foram desenvolvidos novos processos para valoração de petróleos pesados, que recuperam os asfaltenos, obtendo também óleo lubrificante. Neste trabalho foi estudado um dos processos para valoração de petróleos pesados, que utiliza fluidos supercríticos para a desasfaltação e produção de óleo lubrificante. Este processo foi estudado a partir de duas abordagens. A primeira abordagem foi o desenvolvimento de uma planta piloto de desasfaltação supercrítica, no qual o projeto de uma planta piloto construída foi adequado para o uso com petróleo. Este comissionamento foi assistido por simulações do processo realizadas em um software de simulação, no qual as variáveis de processo foram avaliadas em termos de sua influência no desempenho. Diversos testes foram feitos na planta piloto com frações pesadas de petróleos brasileiros, onde as condições operacionais foram avaliadas para a constatação das modificações de projeto necessárias. Uma vez concluída a primeira etapa, foi feita uma segunda abordagem para o processo, que representou o estudo do mecanismo de agregação e precipitação dos asfaltenos, que corresponde à primeira etapa do processo de desasfaltação. Este mecanismo foi avaliado com experimentos utilizando espalhamento de luz dinâmica, para quantificar a variação do tamanho das partículas de asfalteno com o tempo, em amostras preparadas com solventes orgânicos. Como complementação para este estudo, foi utilizada a Espectroscopia Raman Anti-Stokes Coerente para obter imagens das partículas de asfalteno no processo de agregação. Estes dados são de extrema importância, uma vez que ajudam a entender melhor o mecanismo de agregação dos asfaltenos, que ainda permanece como um grande problema sem solução na industria de petróleo e permitem o estudo e avaliação do processo de extração supercrítica para o melhor aproveitamento dos petróleos brasileiros na indústria.<br>Abstract: Alphaltenes are complex aromatic macro-cycle molecules, with a molecular structure that varies depending on the origin of the crude oil. Apart from heir contribution to the properties of petroleum, the study of the asphaltic fraction asbecome more important, due to the problems encountered during petroleum Pro cessing caused by asphaltene precipitation, which causes pipe clogging and catalyst deactivation. Associated with the problems related to the presence of asphalthenes, the petroleum industry developed new processes for upgrading of heavy oils and residues, designed for recovering asphaltenes and lube oil from that mixture. The Residuum Oil Supercritical Extraction (ROSE¿) process is the premier deasphalting technology available in industry. This process extracts high-quality deasphalted oil (DAO) and asphaltenes from atmospheric or vacuum residues and other heavier feedstocks. In this work the extraction of asphaltenes from oil was assessed using two different approaches. The first one was the installation and commissioning of a supercritical deasphalting pilot plant, assisted by simulations using a process simulation software and a thermodynamic study of the system comprised of deasphalted oil, asphaltenes and the solvent. The second approach was the use optical strategies to analyze and model asphaltene aggregation, which is the first step of the supercritical dealphalting process. The first optical technique used was dynamic light scattering (DLS), which gave information such as to study and describe the kinetics of asphaltene aggregation in aromatic solvents, at different temperatures. Associated with the DLS results, CARS (Coherent Anti-Stokes Raman Scattering) images were acquired with different solvents, and allowed an evaluation of the behavior of asphaltenes while they aggregate. These results are very important, once they provide insightful information on the asphaltene aggregation mechanism that still remains as a great unsolved problem in the petroleum industry, allowing it to be controlled in order to reduce problems related with asphaltene precipitation in oil transport and processing and improving the performance of heavy oils upgrading processes.<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química

Oxydation des asphaltenes de quatre petroles lourds avec du tetroxyde de ruthenium et identification des molecules d'acides formees par spectrometrie de masse. L'etude de la ou des fonction(s) acide(s) sur chaque produit, associee a une experience de simulation de maturation sur argile, a conduit a proposer un mecanisme d'incorporation de ces molecules dans les asphaltenes. Il s'agirait de reactions de type fridel-crafts, catalysees par la matrice minerale. L'etude de la structure des resines a ete etudiee par hydrogenolyse avec du nickel de raney et les molecules formees par chromatographie en phase gazeuse couplee a de la spectrometrie de masse

Orientadores: Rubens Maciel Filho, Paula Sbaite Duarte dos Santos<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-19T04:58:43Z (GMT). No. of bitstreams: 1 GordilloCelis_CarlosAlberto_M.pdf: 40097706 bytes, checksum: c60604f84094a693629fd3fbc7ee8c2b (MD5) Previous issue date: 2011<br>Resumo: Esta dissertação baseia-se na valoração da corrente de destilado e da corrente de resíduo geradas na destilação molecular (DM) do petróleo as quais são obtidas a partir do resíduo de vácuo (RV) proveniente da unidade de destilação a vácuo (UDV). Primeiramente se separou os asfaltenos da corrente ultrapesada do resíduo da DM (RDM), seguido do tratamento com solvente da corrente do destilado da destilação molecular (DDM). Duas amostras de RDM foram utilizadas como matéria prima na separação de asfaltenos, a primeira delas, o RDM obtido a temperatura do evaporador (TDM) de 340°C e, a segunda, o RDM obtido a TDM=280°C. Os asfaltenos separados chamaram-se de A, B e C. O asfalteno "A", separado do RDM TDM=340°C e os asfaltenos "C" e "B" foram separados do RDM TDM=280°C. A comparação das massas molares e da distribuição de massa molar das amostras separadas foi analisada a partir dos dados obtidos por cromatografia de permeação em gel, onde as massas molares medias variam entre 3737 e 4232 Da. Ressalta-se que foi necessário o desenvolvimento de um metodo analítico apropriado para analise de petróleo e asfaltenos por cromatografia de permeação em gel. As amostras de asfaltenos separados da corrente do RDM foram ainda caracterizadas por espalhamento de luz dinâmico, espectroscopia de infravermelho por transformada de Fourier, microscopia eletrônica de varredura e espectroscopia de energia dispersiva de raios-X. Na segunda metade do trabalho, utilizando-se como matéria prima a corrente de DDM TDM=340°C, comparando-se quatro amostras, duas provenientes do mesmo petróleo e mais duas, provenientes de petróleos diferentes. Partindo dessas correntes foi realizada, a desaromatizarão e desparafinação o óleo DDM em uma montagem experimental de bancada operada a pressão atmosférica e temperaturas de -7 a 80°C. O gasto energético envolvido nesse processamento se resumiu ao aquecimento e resfriamento do reator e do sistema de agitação magnético. Com o uso de solventes como, furfural e metil isobutil cetona (MIBC), a corrente de DDM deu origem a quatro óleos com características de óleos básicos, caracterizados e classificados segundo as viscosidades e índices de viscosidades dos mesmos, classificando-se como óleo básico neutro pesado, brilhante e cilindro pesado, dentro dos grupos API I e V. Assim, a valoração das correntes RDM e DDM fecha o ciclo de um grande projeto, que começou com alimentação do RV na UDM e finalizou com aproveitamento das correntes geradas dando valor agregado a esses produtos<br>Abstract: This dissertation deals with adding value to the distillate and residual streams of the molecular distillation (MD) of petroleum vacuum residua (PVR), PVR being the residual stream of vacuum distillation unit. First of all, asphaltenes were separated from the molecular distillation ultraheavy stream (MDR), followed by the solvent treatment of the molecular distillation distillate stream (MDD). Two samples of MDR were used as raw material for the asphaltene synthesis: the first was obtained at an evaporator temperature during the MD of 340°C; the second, at TDM=280°C. The molar mass and the molar mass distribution of the two samples were obtained from the gel permation chromatography (GPC) analysis. The asphaltenes with molar masses between 3737 to 4232Da were called "A"; "B" and "C". The asphaltene "A" was separated from MDR 340°C and the asphaltenes "B" and "C" were obtained from MDR 280°C. It's important to highlight that it was necessary to develop an analytic method in order to perform the GPC analysis of the samples. The "A"; "B" e "C" samples were characterized by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In the second phase of this work, four samples of MDD 340°C, two of them obtained from one petroleum, and the two remaining obtained from different petroleums, were used as raw materials for the deparaffinization and dearomatization processes. The experimental procedure was carried out at atmospheric pressure and temperatures between -7 to 80°C. The energy requirement for this process was related to the heating and cooling of the reactor and to the agitation system. The MDD treatment with furfural and methyl isobutyl ketone (MIBK) produced four different oils showing basic oil characteristics. The oils were classified according to their viscosity and viscosity index into heavy neutral, bright stock and heavy cylinder stock. Besides, they were classified into the I and V API groups. Thereby, the fact of adding value to the MDR and MDD streams closes a bigger project that started with the use of petroleum vacuum residua as feedstock of the molecular distillation process and ended with the better utilization of the distillation waste oil streams<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química

Made available in DSpace on 2016-12-23T14:41:50Z (GMT). No. of bitstreams: 1 Emanuele Catarina da Silva Oliveira.pdf: 3488830 bytes, checksum: fc0d45235f94ffa597f9bb41f45af330 (MD5) Previous issue date: 2013-03-25<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Heavy crude oils have attracted a growing interest from oil industries around the world. In this scenario, asphaltenes, which are molecules known for their low reactivity and high molecular weight, have received special attention in recent decades, due to the problems they cause during oil processing. In an effort to minimize these problems, researchers have increasingly looked for a better understanding of aspects such as molecular structure, stability and physicochemical properties of asphaltenes, as well as for the development of methods to prevent their unwanted precipitation. In recent decades, nuclear magnetic resonance (NMR) has been widely used as a tool for the study of petroleum and its derivatives. The analysis of 1H and 13C NMR spectra allows the direct determination of a series of structural parameters such as the fractions of aromatic carbons and of carbon atoms in alkyl chains. Diffusion-ordered NMR spectroscopy (DOSY), which is based on the results of pulsed-field gradient (PFG) experiments, is a new developed NMR technique highly useful for the elucidation of complex mixtures. This work sought to identify the differences in average molecular parameters of asphaltenes from national crudes and to correlate them with the physicochemical properties of the asphaltene and of the original crude. The aim was also to investigate and to compare the asphaltenes among themselves, using data such as diffusion coefficient, concentration of these compounds in the oil and state of aggregation. Extraction and quantification of the amount of asphaltenes were performed using ASTM D6560-00 standard and the characterization of the asphaltenes was performed using the following analytical techniques: elemental analysis, atomic absorption spectrometry, mass spectrometry, high-resolution 1H and 13C NMR and DOSY. Significant changes were observed in almost all studied parameters. To study the asphaltene aggregation behavior using DOSY, the asphaltenes were diluted in various concentrations of deuterated toluene and the DOSY spectra were correlated with their respective states of aggregation. The diffusion properties were highly dependent on the concentration and type of oil from which the asphaltene was extracted<br>Os petróleos pesados são de grande interesse das indústrias petroleiras ao redor do mundo. Com isso, os asfaltenos, moléculas conhecidas por sua baixa reatividade e alto peso molecular, têm recebido uma atenção especial nas ultimas décadas, devido aos problemas que causam durante o processamento do óleo. Buscando minimizar estes problemas, pesquisadores têm investido cada vez mais no conhecimento da estrutura molecular e estabilidade dos asfaltenos, no entendimento de suas propriedades físico-químicas e no desenvolvimento de metodologias que impeçam sua precipitação indesejada. Nas últimas décadas, a ressonância magnética nuclear (RMN) tem sido amplamente utilizada como ferramenta no estudo de petróleos e seus derivados. A obtenção de espectros de RMN de 1H e 13C permite a determinação direta de uma série de parâmetros estruturais, tais como a fração de carbonos aromáticos e de carbonos ligados em uma cadeia alquílica. O desenvolvimento de novas técnicas de RMN, como a espectroscopia de RMN ordenada pela difusão (DOSY), baseada na sequência de gradiente de campo pulsado (PFG), têm se mostrado excelentes ferramentas na elucidação de misturas complexas. Neste trabalho, procurou-se identificar as diferenças observadas nos parâmetros moleculares médios dos asfaltenos provenientes de petróleos nacionais, bem como correlacioná-las com as propriedades físico-químicas do próprio asfalteno e do óleo de origem. Pretende-se, ainda, investigar e comparar os asfaltenos, a partir de dados de coeficiente de difusão, concentração desses compostos no óleo e forma de agregação. A extração e quantificação do teor de asfaltenos foram realizadas utilizando-se a norma ASTM D6560-00 e a caracterização dos asfaltenos foi realizada através das técnicas analíticas de: análise elementar, espectrometria de absorção atômica, espectrometria de massas de alta resolução, RMN de 1H e 13C e, RMN DOSY. Foram observadas modificações significativas em praticamente todos os parâmetros estudados. No estudo do comportamento de agregação com a técnica RMN DOSY os asfaltenos foram diluídos em concentrações diferentes de tolueno deuterado e os espectros correlacionados com os seus respectivos estados de agregação. As propriedades de difusão se mostraram altamente dependentes da concentração e do tipo de óleo utilizado para a obtenção dos asfaltenos

Du fait des problèmes industriels reliés aux asphaltènes lors de l’extraction, du traitement et du transport des hydrocarbures, les champs pétrolifères sont développés de manière conservatrice avec des moyens de prévention de dépôts surdimensionnés. Les répercussions économiques sur les architectures et les opérations se quantifient en centaines de millions de dollars par an autour du globe terrestre.De nombreuses études menées sur les asphaltènes dans des solvants dispersants, tels que les solvants aromatiques, ont permis une description extensive des propriétés et structures moléculaires des asphaltènes durant les 20 dernières années. Malgré la connaissance accrue sur les dispersions d’asphaltènes en solution colloïdales, leur incompatibilité avec certains composés plus légers, tels que les alcanes, demeure mal comprise. En effet, la présence d’alcanes ou d’autres constituants légers comme le dioxyde de carbone induit une déstabilisation des asphaltènes. Sous ces conditions de mélanges, ceux-ci tendent à s’agréger et/ou à s’accumuler sur les parois des installations. De nombreuses études montrent que les théories de transfert de masse peuvent expliquer ces phénomènes dans des solution de pétrole + alcanes liquides préparées en laboratoire. Plus la concentration volumique de mauvais solvants est grande dans la solution, plus la quantité d’asphaltènes instables et leur vitesse d’agrégation sont grandes. En réalité, la décroissance de la pression dans les conduites, pendant l’écoulement du fluide, induit une augmentation significative du volume des composés hydrocarbures légers ou du CO2. Ainsi, avec l’allègement du solvant liquide certaines fractions d’asphaltènes peuvent être déstabilisées et causer des problèmes. Des expériences de solutions liquides à pression atmosphérique ont précédemment été conçues pour ajuster des paramètres théoriques nécessaires aux modélisations, tels que la constante d’agrégation des asphaltènes instables, leur nombre ou leur diffusivité. En revanche, ces coefficients sont inconnus dans les conditions de déstabilisation industrielles en raison de la difficulté à les déterminer expérimentalement. En pratique, ceci limite la prédiction des risques de dépôts d’asphaltènes dans des cas industriels. La volonté de cette thèse est d’améliorer la prédiction du comportement des asphaltènes dans les conditions d’opérations de l’industrie pétrolière. Son objectif est d’abord de développer la compréhension des systèmes liquides aux conditions atmosphériques afin d’en extraire les mécanismes dominants et limitants. Dans un premier temps, les observations expérimentales sont donc menées sur des mélanges de pétrole et d’heptane. Une fois les mécanismes bien compris, un parallèle est réalisé avec d’autres alcanes, dont le methane.La première partie de cette dissertation est une investigation des deux phénomènes qui ont lieu simultanément dans la phase liquide pendant l’ajout ininterrompu d’heptane : la déstabilisation et l’agrégation des asphaltènes en suspension.Dans une seconde partie, l’utilisation d’un résonateur en cristal de quartz, immergé dans le fluide d’étude, permet pour la première fois de mesurer la quantité de dépôt d’asphaltènes pendant le changement continu du solvant. Le modèle de diffusion proposé pour expliquer le transfert de masse des asphaltènes dans le fluide vers la surface solide est en accord avec de précédentes recherches. Les particules primaires d’asphaltènes instables sont identifiées comme contributrices principales du processus de déposition et le taux de changement de composition volumique de la solution liquide est un facteur dominant de leur génération.En dernière partie, les concepts ci-dessus sont vérifiés pour des systèmes à gaz dissouts avec un appareil analogue à capteurs immergés sous pression. Pour la première fois, le taux de déposition et la concentration en asphaltènes instables peuvent être quantifiées, en laboratoire, au cours d’une dépressurisation d’un pétrole<br>Asphaltenes have been known, since decades, to occasionally cause severe industrial problems during crude oil extraction and during its transport. Petroleum fields are apprehensively developed with oversized and costly prevention approaches due to the limited understanding on asphaltenes deposition in conditions of oil production.Previous fundamental researches provided extensive descriptions of asphaltenes properties in good solvents, such as aromatic solvents. The incompatibility of asphaltenes with alkanes induces their destabilization, their aggregation and their deposition. The aggregation and the mass transfer behavior of asphaltenes have been explained by theoretical concepts for oil + liquid alkane systems. The amount of destabilized asphaltenes and their aggregation rate both increase as the volume fraction of the anti-solvent increases. Quantitative laboratory measurements have been accordingly developed for liquid systems at atmospheric pressure. However, risks related to the instability of asphaltenes are only qualitatively understood during the primary production of crude oils. In the oil fields, the pressure decrease of the oil causes the light constituents, such as methane or carbon dioxide, to increase their volume fraction in the liquid phase. Experimental determination of theoretical parameters related to asphaltene deposition under pressure is therefore a key.The first part of this dissertation addresses the understanding of bulk behavior (destabilization and aggregation) related to asphaltenes in oil-heptane systems. Analytical equations are proposed to distinctly model both phenomena. Numerical results obtained by combining both equations provide excellent agreements with experimental measurements. The study reconciles the continuum consideration of asphaltene molecules in crude oils with the notion of flocculation "onset" by distinguishing the destabilization and the aggregation kinetics. A reasonable match is found between the transition of the theoretical and the adjusted colloidal stability ratio, indicating that underlying physics are captured by considering simultaneous destabilization and aggregation kinetics.A fully immersed quartz crystal resonator is used to record the mass of deposit on solid surfaces in contact with varying liquid solutions. The deposition rate of asphaltenes is studied during continuous addition of heptane. A diffusion-limited model, designed for studied geometry, can explain experimental results and agrees with previous research on different apparatus. The mass transfer relationship reveals that primary unstable aggregates of asphaltenes mainly contribute to the deposition process and have an average hydrodynamic radius of 7 nanometers (± 50%). A linear relationship is found between the generation rate and the deposition rate of unstable asphaltenes in the investigated conditions. However, the initial presence of large suspending unstable aggregates slows down the asphaltenes deposition process.In the last phase of this work, the validity of defined concepts for the destabilization, the aggregation and the deposition induced by heptane additions is verified for oil-methane systems. The rate of change of solution properties is found to be the predominant variable affecting the deposition of asphaltenes. The effect of methane is significantly more pronounced than liquid alkanes on the asphaltene deposition.For the first time, the bulk concentration of unstable asphaltenes and their deposition rate can be quantitatively measured during the depressurization of live oils (light constituent dissolved). Although first tendencies are de-rived from this work, the effect of the anti-solvent nature still needs further research with the identified variables in order to fully elucidate the thermodynamic driving quantity which controls the amount of destabilized asphaltenes

Orientadores: Rubens Maciel Filho, Maria Izabel M. S. Bueno<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica<br>Made available in DSpace on 2018-08-11T19:29:50Z (GMT). No. of bitstreams: 1 Henriques_ClaudeteBernardo_M.pdf: 3645834 bytes, checksum: 16d6c77b7c64c77aaf38edbfb3f50d60 (MD5) Previous issue date: 2008<br>Resumo: No mundo inteiro, a demanda por petróleo tem aumentado ao mesmo tempo em que as reservas de petróleos leves têm diminuído drasticamente. Neste cenário, a alternativa de exploração de óleos pesados, principalmente oriundos de águas profundas localizadas em regiões costeiras, tem se intensificado. Esta alternativa altera em muito os procedimentos padrão de refinarias, como também tem exigido uma rápida e confiável forma de caracterização destas amostras, que têm como características principais baixos valores de grau API, alta viscosidade, altos teores de asfaltenos e resinas, assim como a presença de compostos oxigenados, nitrogenados, organometálicos e impurezas oleofóbicas. Para preencher parte desta lacuna, esta dissertação apresenta um novo método analítico, adequado para análises de rotina, baseado na correlação de Espectrometria de Raios-X e alguns dos parâmetros mencionados acima, como determinação do teor de asfaltenos, de metais, de grau API, assim como a classificação dos petróleos em leves e pesados. As correlações são obtidas através de modelamento quimiométrico dos espectros com dados obtidos através de métodos padrão IP 143-1984(89) e/ou ASTM D6560-00 para o teor de asfaltenos, ASTM D 5708-05 e ISO 14597-97(E) para o teor de níquel, vanádio e ferro por ICP (do inglês, inductively coupled plasma) e XRS (do inglês, X-ray Spectrometry), respectivamente. Estes métodos padrão são inadequados para análise de rotina, já que se apresentam, em alguns casos, como laboriosos, demandando tempo, uso exaustivo de reagentes, gerando, portanto, resíduos quase sempre tóxicos. O uso do espalhamento raios X como sinal analítico para a determinação do teor de asfaltenos é fundamental para abrir uma nova perspectiva em se empregar a XRS (do inglês, X-ray Spectrometry) para análise desta propriedade, apresentado resultados que superaram os até então obtidos para correlação com o método de referência IP 143-1984 (89). Os modelos foram obtidos pelas ferramentas PCA (do inglês, Principal Component Analysis) e PLS (do inglês, Partial Least Square Regression), obtendo-se correlações acima de 0,9 entre os valores previstos e medidos pelos métodos padrão. Assim, esta dissertação é pioneira, já que visa incentivar o desenvolvimento de novos trabalhos correlatos<br>Abstract: In the whole world, the petroleum demand is increasing whereas light oils reserves are deeply decreasing. In this scenery the exploration of off-shore heavy oils in coastal deep waters is urgent. This alternative deeply alters the standard procedures in petroleum refineries and requires fast and reliable sample characterization methods. The samples present as main features low API degrees, high viscosity, high asphaltene and resin contents, the presence of oxygenated, nitronenated and organometallic compouns, as well as oleophobic impurities. To fill a part of this blank, this work shows the development of a new analytical method, nicely applicable to routine, based on the correlation of X-ray Spectrometry (XRS) and some of the parameters mentioned above, as the determination of asphaltene and metal contents, of API degree, as well as the classification of samples as light or heavy petroleums. The correlations are reached through chemometric modelling between the spectra and data obtained by standard methods IP 143-1984(89) and/or ASTM D6560-00 for asphaltene content, ASTM D 5708-05 and ISO 14597-97(E) for nickel, vanadium and iron determinations by ICP (Inductively Coupled Plasma) and XRS (X-ray Spectrometry), respectively. All the standard methods are inadequate for routine analysis, since they are laborious, extremelly reagent- and time-consuming, generating toxic residuals. The use of X-ray scattering as analytical signal to determine asphaltene content is fundamental to open a new perspective in X-ray Spectrometry, showing better performance than reference method (IP 143-1984(89)). The models were obtained by applying chemometric tools, as PCA (Principal Component Analysis) and PLS (Partial Least Square Regression), with correlation coefficients above 0.99 between measured and previewed values. So, this work is pioneer, opening new possibilities for future simultaneous applications in petroleum and co-products characterizations<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química

Orientador: Rubens Maciel Filho<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-18T00:25:55Z (GMT). No. of bitstreams: 1 Lodi_Leandro_M.pdf: 2994476 bytes, checksum: 76d1a0310770d2c2352f95d0f41c04af (MD5) Previous issue date: 2011<br>Resumo: A crescente demanda por óleos leves nas últimas décadas está forçando a indústria de petróleo a desenvolver processos novos e mais eficientes, além de adaptar e otimizar os existentes no processamento dos óleos crus pesados, extra-pesados e seus resíduos. A extração com diferentes solventes na região do supercrítico apresenta-se como alternativa técnica potencialmente viável quando comparada à extração convencional. O uso do fluido supercrítico possui algumas vantagens como: maior rendimento, melhor qualidade do produto óleo desasfaltado (ODES) e do asfalto, bem como a acessibilidade de recuperação do solvente. Entretanto, um importante passo no estudo destes processos, para viabilização industrial, têm-se os testes em escala piloto, nos quais se inicia a definição das variáveis de processo e econômicas. Os processos piloto fazem parte de etapas importantes para definição da viabilidade ou não de um processo, fornecendo, ainda, importantes dados para as avaliações de segurança do processo e estabelecimento das salvaguardas, as quais estabelecerão um processo seguro para operadores e instalações. Neste trabalho é apresentada uma proposta de montagem de unidade piloto para processo de desasfaltação em diferentes condições de operação. Tal processo servirá para pesquisa de novas alternativas com possibilidade de variações das condições de processo: temperatura, pressão e composição. O processo possibilitou que os resultados obtidos por meio dos experimentos sejam confiáveis e passíveis de implantação em processo industrial em grande escala<br>Abstract: The increase demand for light oils in the last decade is carrying to the petroleum industry to develop new processes and more efficient, besides to adapt and to optimize the existent process related to the crude oil (being heavy and extra - heavy) and its fractions obtained from distillation processing. Extraction process with different solvents in the supercritical area represents an alternative technique potentially viable when compared to conventional extraction. The supercritical fluid has specific advantages such as: higher yield, better quality of deasphalted oil and the asphalt, and also, the solvent recovery. Furthermore, experimental trials in a pilot scale are considered important tool to study these processes in terms of the operating and economic variables. In accordance to Seider and co-workers (2003), processes in pilot scale make part of the important steps for feasibility definition or not of them. In addition, the pilot process provides significant data for safe process and safety-guard evaluation, to apply in the safety of people and locations. In this work is presented a proposal for assembling a deasphalting pilot unit which will be operated at different conditions (temperature and pressure) in the normal region (related to liquid phase) and supercritical region. This study allowed to obtain important results regarding to screening variables of the deasphalting process. In the same sense, results showed that collected data are reliable and they might be used for the implantation in a large scale of the process<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestre em Engenharia Química

Orientador: Paulo Roberto Ribeiro<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociência<br>Made available in DSpace on 2018-08-21T19:58:43Z (GMT). No. of bitstreams: 1 Paes_DiogoMelo_M.pdf: 2739943 bytes, checksum: 4213b100e22039aa35e9bbceb5f52418 (MD5) Previous issue date: 2012<br>Resumo: Durante a produção de petróleo, partículas de asfalteno podem ser precipitadas da fase líquida devido a variações de pressão, temperatura e composição ao longo da trajetória do fluido do reservatório até a superfície. Uma vez precipitadas, essas partículas podem se depositar na parede de colunas de produção, reduzindo a área aberta ao escoamento e, consequentemente, a vazão. Apesar da importância do tema, a literatura sobre a deposição de asfaltenos em poços (incluindo modelos teóricos e dados experimentais) é escassa. Para superar as dificuldades inerentes a pouca literatura existente sobre o assunto, possibilitando um melhor entendimento desse complexo problema de transferência de massa, uma consistente metodologia foi proposta nesta dissertação. Essa metodologia envolveu uma revisão de literatura sobre conceitos fundamentais de transferência de quantidade de movimento e sobre a teoria da deposição de partículas, situando a deposição de asfaltenos em um contexto mais amplo, da deposição de partículas durante escoamentos turbulentos. Seis modelos de deposição (Lin et al. 1953; Friedlander e Johnstone 1957; Beal 1970; El-Shobokshy e Ismail 1980; Papavergos e Hedley 1984; Escobedo e Mansoori 1995) são estudados e validados com quatro conjuntos de dados experimentais de deposição de aerossol (Friedlander 1954; Wells e Chamberlain 1967; Liu e Agarwal 1974; Agarwal 1975). Com base nos resultados desse estudo, o modelo de Beal (1970) foi selecionado como sendo o mais adequado para prever a deposição de partículas, sendo considerado adequado também para prever a deposição de asfaltenos (limitando-se sua aplicação a intervalos similares de número de Reynolds, número de Schmidt e tempos de relaxação adimensionais em relação àqueles cobertos no estudo de validação). Por fim, esse modelo foi aplicado em uma análise de sensibilidade para se avaliar os parâmetros e mecanismos de transporte mais importantes para a deposição de asfaltenos em poços<br>Abstract: During petroleum production, asphaltene particles can precipitate from the crude oil due to pressure, temperature, and composition changes along the fluid path from the reservoir to the surface. Once precipitated, those particles can deposit in the inner surface of production tubings, restricting the available flow area and reducing flow rates. Despite the importance of the theme, the literature about asphaltene deposition in wellbores (including theoretical models and experimental data) is scarce. To overcome the difficulties inherent to that shortage of literature and enable a better understanding of that complex mass transfer problem, a consistent methodology is proposed in this work. That methodology involved a comprehensive review of fundamental concepts of the mass transfer and particle deposition theories, placing the asphaltene deposition within a more general context, of particle deposition during turbulent flow. Six published particle deposition models (Lin et al. 1953; Friedlander and Johnstone 1957; Beal 1970; El-Shobokshy and Ismail 1980; Papavergos and Hedley 1984; Escobedo and Mansoori 1995) are studied and validated with four published aerosol experimental data sets (Friedlander 1954; Wells and Chamberlain 1967; Liu and Agarwal 1974; Agarwal 1975). Based on the results of the study, Beal's (1970) model was selected as the most suitable to predict particle deposition and was considered adequate also to predict asphaltene deposition (limiting its application to similar ranges of Reynolds numbers, Schmidt numbers and dimensionless relaxation times in relation to those covered in the validation study). Finally, that model was applied in a sensitivity analysis to evaluate the most important parameters and transport mechanisms governing asphaltene deposition in wellbores<br>Mestrado<br>Explotação<br>Mestre em Ciências e Engenharia de Petróleo

Orientadores: Rubens Maciel Filho, Maria Izabel Maretti Silveira Bueno<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-18T14:39:31Z (GMT). No. of bitstreams: 1 Henriques_ClaudeteBernardo_D.pdf: 9506603 bytes, checksum: 875e508c591361025ae37d3b9ac0f432 (MD5) Previous issue date: 2011<br>Resumo: Esta tese tem como objetivo apresentar um estudo detalhado para a caracterização de petróleos, tanto no âmbito do desenvolvimento de modelos capazes de prever propriedades físico-químicas clássicas, como também avaliar os fenômenos associados a instabilidades decorrentes de características químicas. Para alcançar este objetivo, duas ações foram executadas: (1) Obter a curva de destilação do ponto de ebulição verdadeiro (PEV) através de simulação, por espectrometria de espalhamento de raios-X (EERX) aliada ao algoritmo denominado máquina vetor de suporte (SVM), com o propósito de prever o rendimento do processo de refino, e (2) Caracterizar o petróleo em relação ao fenômeno de agregação dos asfaltenos, para assim possibilitar a previsão da qualidade do processo de refino. Foram avaliadas amostras de petróleos com propriedades distintas, com o intuito de fornecer amplitude e robustez ao estudo. A primeira abordagem foi à análise classificatória dos petróleos em relação às suas propriedades intrínsecas (teor de enxofre, Grau API e ponto de ebulição verdadeiro), com aplicação de métodos multivariados de classificação. Com estas classificações em mãos, foram desenvolvidos modelos para previsão da curva PEV e do Grau API, utilizando o algoritmo SVM (segunda abordagem). Os dados tratados por meio deste algoritmo apresentaram um perfil de não linearidade. Os resultados obtidos para a caracterização das cargas a partir dos modelos não foram significativamente diferentes dos valores experimentais, permitindo o desenvolvimento de estudos computacionais usando o software comercial Petro-SIM®, para caracterização, aquisição das curvas das misturas de petróleos e, finalmente, previsão dos rendimentos dos cortes na simulação de uma torre de destilação atmosférica. A partir destes resultados, é muito importante ressaltar que, ao contrário da maioria das modelagens quimiométricas, um pequeno grupo de amostras foi necessário para o desenvolvimento do modelo (13 amostras). Vale também serem mencionadas a alta capacidade de previsão do modelo, a rápida e eficiente previsão de curvas PEV de amostras de petróleos puros, processados nas refinarias e, finalmente, a aplicação com sucesso destes modelos em simuladores de processo. A terceira abordagem do trabalho foi à avaliação dos aspectos relacionados à existência de formas coloidais dos asfaltenos, peptizados por resinas e dos efeitos relacionados à presença de outros solventes nos petróleos, que podem causar mudanças na cinética de floculação dos asfaltenos. A composição dos solventes (petróleos diluentes) e dos petróleos pesados foi correlacionada com os resultados do estudo cinético, obtido por meio da avaliação da transmitância por varredura óptica da camada de precipitação dos particulados e da floculação dos asfaltenos, como também por modelos dinâmicos. Para isto, foram elaboradas misturas de petróleos e observou-se que os efeitos associados ao fenômeno de agregação estão diretamente correlacionados com a composição dos petróleos, assim como com a presença de particulados nas misturas. A caracterização adequada dos constituintes de petróleo é uma informação indispensável para garantir o processamento adequado nas refinarias. A reprodução do cenário real do processo, por meio da simulação, foram promissores, mostrando que a caracterização da carga é possível ao se trabalhar com os modelos desenvolvidos, reforçando a relevância das técnicas aplicadas para descrição dos fenômenos químicos associados ao cenário de produção nacional<br>Abstract: This work aims to present a detailed study for petroleum characterization, through model developments able to preview physical chemical properties and also to evaluate the associate phenomena due to instability in current chemical characteristics. For this purpose two actions were executed: (1) To obtain the curve true boiling point (TPB) through the simulation by spectrometry X-ray scattering (EERX) combined with the algorithm called support vector machine (SVM), in order to predict the yield of the refining process, and (2) to characterize the petroleum in respect to asphaltene aggregation phenomena, making possible the prediction of the quality of the refining process. For these purposes, the petroleum samples were evaluated with different properties, providing amplitute and robustness to the study. The first approach was the classificatory analisis of petroleum in relation to intrinsic properties (sulfur contents, API degrees and true boiling point curves) with application of classification multivariate methods. With these classifications in hands, models were developed to predict the TBP curve and API gravity, using the algorithm SVM (second approach). The data were processed by this algorithm, showing nonlinear profiles. The results for the blend characterization using the models were not significantly different from the experimental values, allowing the development of computational studies using the commercial software Petro-SIM® for characterization, acquisition of mixtures curves and finally, prediction of the cuts yield in the simulation of an atmospheric distillation tower. From these results, it is important to emphasize that a small group of samples was necessary for the model development (13 samples). It is also worth to mention the high predictive ability of the model, the rapid and efficient prediction of TBP curves of crude oil samples, processed in the refineries and finally, the successful application of these models in process simulators. The third approach of this work was to evaluate the aspects related to the existence of colloidal forms of asphaltenes, peptized by resins and of effects related to the presence of other solvents in oils, which can cause changes in the kinetics of flocculation of asphaltenes. The composition of solvents (thinner oil) and of heavy crude oils were correlated with the results of kinetic study, obtained by evaluating the transmittance for optical scanning of the layer of precipitation of particles and the flocculation of asphaltenes, but also by dynamic models. For this, petroleum mixtures were prepared and it was observed that the effects associated to aggregation phenomena are correlated with the petroleum composition as well as the particulate presence in mixtures. The adequate characterization of petroleum constituents is essential information to ensure proper processing in refineries. The reproduction of real scenario of the process, through the simulation, were promising, showing that the blend characterization is possible when working with these developed models, reinforcing the relevance of the techniques applied for describing the chemical phenomena associated with the setting of national production<br>Doutorado<br>Desenvolvimento de Processos Químicos<br>Doutor em Engenharia Química

Orientadores: Maria Regina Wolf Maciel, Viktor Oswaldo Cárdenas Concha<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-23T23:08:11Z (GMT). No. of bitstreams: 1 Lodi_Leandro_D.pdf: 3500149 bytes, checksum: e2f6137e393deb4f4e4663e466189731 (MD5) Previous issue date: 2013<br>Resumo: Atualmente, o Brasil tem uma grande demanda do consumo de asfalto, devido à reconstrução ou à construção de novas estradas. Para garantir essa demanda, não somente no aspecto quantitativo, mas também visando melhorar a qualidade do asfalto, o mercado busca o desenvolvimento de tipos de pavimentação de alta durabilidade, com as misturas de alto módulo (MAM). Este projeto tem por objetivo geral o estudo do processo de desasfaltação supercrítica em escala piloto de resíduos pesados e ultrapesados do petróleo obtidos por destilação a vácuo convencional. Diversos solventes de extração principalmente a água, etanol e o CO2 foram testados e comparados com o propano, que é o solvente que é utilizado no processo de desasfaltação, e cujos estudos foram desenvolvidos no Laboratório de Otimização, Projetos e Controle Avançado (LOPCA), no Laboratório de Desenvolvimento de Processos de Separação (LDPS) e no Laboratório de Valoração de Petróleo (VALPET) da FEQ/UNICAMP. O trabalho visa introduzir ganhos operacionais, tais como a redução de tempo de processamento e o aumento da quantidade dos materiais obtidos, ou seja, otimização do processo. Um estudo computacional (usando simulador comercial) de um processo de desasfaltação supercrítica também foi realizado, estudando as propriedades termodinâmicas e operacionais do processo, o qual possibilita obter ganhos operacionais. Neste projeto, foram realizados experimentos de extração supercrítica ou quase-crítica de asfaltenos e resinas de resíduos de petróleo, visando obtenção dos dados da unidade de separação supercrítica já desenvolvida e a otimização do processo, utilizando planejamento experimental. Com o desenvolvimento do projeto foi possível separar compostos de petróleo com os solventes: água, CO2 e etanol, além do propano já utilizado nos processos industriais. Finalmente, o estudo apresenta novas técnicas de extração no processo de desasfaltação com solventes promissores considerados menos agressivos ao meio ambiente.<br>Abstract: Nowadays, Brazil has a large demand for asphalt due to reconstruction and/or construction of new roads. In order to assure this request, not only in the quantitative aspect, but also to improve the quality of asphalt, the market searchs for the development of pavement types of high durability, with mixtures of high modulus (MAM).This thesis has as general objective to study the process of supercritical deasphalting in pilot scale of heavy and superheavy petroleum waste obtained by conventional vacuum distillation process. Several extraction solvents mainly water and CO2 was tested and compared with propane which is the solvent used in the deasphalting process, and whose studies were developed at Optimization, Design and Advanced Control Laboratory (LOPCA), and at the Laboratory of Separation Process Development (LDPS) and at the Laboratory of Petroleum Valuation (VALPET) at School of Chemical Engineering (FEQ), State University of Campinas (UNICAMP). The work aims to replace the process of liquid-liquid extraction currently used for conventional deasphalting, trying to introduce operating gains, such as reduced processing time and increasing the quantity of materials obtained, i.e., process optimization. A computational study (using commercial simulator) of a supercritical deasphalting process also be performed, studying the thermodynamic and operational properties of process, which allows to achieve operational gains. In this thesis, experiments of supercritical or quasi-critical extraction of asphaltenes and resins of waste petroleum be performed in order to obtain data from the supercritical separation unit already developed and built up at the laboratories and for process optimization using experimental planning. With the development of the project has been possible to separate petroleum compounds with solvents: water, CO2 and ethanol, as well as the propane used in industrial processes. Finally, the study presents new extraction techniques in the process of solvent deasphalting promising considered less harmful to the environment.<br>Doutorado<br>Desenvolvimento de Processos Químicos<br>Doutor em Engenharia Química

Orientadores: Paulo de Tarso Vieira e Rosa, Hervé Carrier<br>Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química<br>Made available in DSpace on 2018-08-26T16:53:18Z (GMT). No. of bitstreams: 1 Cardoso_FelipeMauroRena_D.pdf: 12991377 bytes, checksum: 45dc2cfba21cc06f3ea5d3950d14b090 (MD5) Previous issue date: 2014<br>Resumo: As atividades de produção de petróleo são fortemente dependentes do comportamento de fase dos fluidos produzidos. Entre as possíveis mudanças de estado, aquelas que conduzem ao aparecimento de uma ou mais fases sólidas são as que apresentam o maior risco à produção de petróleo. A floculação dos asfaltenos, principais componentes da fração pesada e polar do óleo, pode levar à formação de sólidos nas diversas etapas da produção de petróleo. O comportamento de fases dos asfaltenos é bastante complexo, que de certa forma impacta na previsão, prevenção e remediação dos problemas causados por esta fração. Por este motivo, nesta tese, avaliaram-se diversas metodologias para estudar o comportamento de fases dos asfaltenos em condições de alta pressão. Dentre as metodologias, foi desenvolvida uma baseada na técnica do ressonador de cristal de quartzo (RCQ), capaz de identificar as condições termodinâmicas de mudanças de fases em fluidos pressurizados, contendo baixo teor de asfaltenos. Os dados obtidos com o RCQ foram validados pelas técnicas de filtração isobárica e microscopia em alta pressão (MAP). Aplicando as três técnicas citadas, a influência da adição de gases, os fatores cinéticos, as condições termodinâmicas e a influência da taxa de despressurização sobre a floculação dos asfaltenos foram estudados. Óleos vivos foram avaliados pela técnica de MAP, cujos resultados sugerem a existência de quatro tipos de comportamento de fases para experimentos de despressurização isotérmica, destacando-se a existência de equilíbrio líquido-líquido em temperaturas e pressões elevadas. A caracterização físico-química dos asfaltenos extraídos de óleo morto com n-heptano, sugerem que a diferença de aromaticidade entre esta fração e os seus referidos óleos, pode ser um parâmetro indicativo de possível problema de floculação dos asfaltenos durante a produção de petróleo<br>Abstract: Oil production activities are strongly dependent on the phase behavior of produced fluids. Among the possible phase changes, those that lead to one or more solid phases appearances presents the greatest risk to oil production. The flocculation of asphaltenes, the major components of the heaviest and most polar fraction of crude oil, can lead to solids formation in several steps of oil production. Asphaltenes phase behavior is quite complex, which somehow impacts in the prediction, prevention, and remediation of problems caused by this fraction. For this reason, in this thesis, we evaluated several methodologies applied for asphaltenes phase behavior under high-pressure conditions. Among the methodologies, we had developed a technique based on the quartz crystal resonator (QCR), able to identify thermodynamic conditions of phase changes in pressurized fluids containing low asphaltenes content. The data obtained with the QCR were validated by isobaric filtration and high pressure microscopy (HPM) tests. Applying the three aforementioned techniques, the influence of gas addition, kinetic factors, thermodynamic conditions and the influence of depressurization rate on the onset of asphaltenes flocculation were studied. Live oils were evaluated by the HPM technique. The results from HPM suggest the existence of four phase behavior kinds for isothermal depressurization experiments, highlighting the existence of a liquid-liquid equilibrium at elevated temperatures and pressures. The physico-chemical characterization of asphaltenes extracted with n-heptane from dead oil suggests that the difference of aromaticity between this fraction and its referred oils, could be a parameter to indicate possible problems of asphaltenes flocculation during the oil production<br>Doutorado<br>Físico-Química<br>Doutor em Ciências

Made available in DSpace on 2016-08-19T12:56:42Z (GMT). No. of bitstreams: 1 Dissertacao Irata.pdf: 3144382 bytes, checksum: c6e6615b3bf42aec9baa1245f95165df (MD5) Previous issue date: 2013-10-04<br>The oil´s behavior s study, mainly the hard fractions, including asphaltenes and resins, have became extremely important, since the relations between theses constituents during the oil mixing operations and its derivatives may bring several problems with the asphaltenes precipitance. Undesirable, the precipitance may cause pipe s obstruction during the oil s extraction, slowing down the production and rising up the expenses. These facts have motivated this work, that seek determine the influence of temperature and adding particulate materials, in the beginning of asphaltenes precipitation (IP) in models solutions, intending in better characterize the precipitation process, once many of the models applied to determinate the stability and compatibility between these oils, for example, are based on data from the beginning of the precipitation (IP). The technique spectroscopy near Infrared was used to determine the precipitation of asphaltenes in the temperature range from 10 to 30 ºC and with different particle materials (calcareous, sandstone, clay) and a optical microscopy technique determining IP with no temperature variations, contributing as basis for the obtained value, using the NIR technique. The results will designate the temperature variation, with little influences on precipitation, according to the literature. Particle adding (calcareous and clay) have proved to be significant, modifying significantly the asphaltenes precipitation outset, however, the same thing hasn t been noticed with the sandstone particles.<br>O estudo do comportamento do petróleo, principalmente das frações pesadas, que incluem asfaltenos e resinas, tem se tornado extremamente importante, visto que as relações entre esses constituintes durante as operações de misturas de petróleos e de petróleos e seus derivados, podem trazer inúmeros problemas com a precipitação dos asfaltenos. Indesejável, a precipitação pode ocasionar obstruções de tubulações durante a extração do petróleo, diminuindo a produtividade e aumentando os custos, o que motivou a realização deste trabalho que objetiva determinar a influência da temperatura e da adição de materiais particulados, no início de precipitação (IP) dos asfaltenos em soluções modelos, no intuito de melhor caracterizar o processo de precipitação, uma vez que muitos dos modelos empregados para determinar a estabilidade e a compatibilidade entre petróleos, por exemplo, baseiam-se nos dados do início de precipitação. A técnica de Infravermelho Próximo (NIR) foi utilizada para determinar o início de precipitação (IP) dos asfaltenos na faixa de temperatura de 10 a 30ºC e com diferentes materiais particulados (calcário, arenito e argila) e a técnica de microscopia óptica na determinação do IP servindo como base para os valores obtidos com uso da técnica NIR. Os resultados indicaram variações de temperatura, pouco influentes na precipitação, em acordo com a literatura. As adições de particulados (calcário e argila) mostraram-se significativas, alterando relevantemente o início de precipitação dos asfaltenos, no entanto, o mesmo não foi observado para os particulados de arenito.

L'objectif de ce travail est d'étudier par simulation de dynamique moléculaire le comportement des sous-fractions d'asphaltènes A1 et A2 en solution, en présence d'une nanoparticule de silice. Les sous-fractions d'asphaltènes A1 et A2 sont obtenues expérimentalement à partir d'un traitement des solutions d'asphaltènes au p-nitrophénol dans le cumène. Le travail se divise en deux parties. La première partie concerne le comportement des sous-fractions en solution dans le toluène et a permis de déterminer les conditions de calcul et de sélectionner les meilleurs modèles représentant ces sous-fractions. Ensuite, une série de modèles a été proposée et leur comportement dans l'heptane, le THF et le chloroforme a été caractérisé. En outre, les paramètres de solubilité de chaque modèle ont été calculés et comparés aux valeurs de la littérature. Le logiciel de calcul GROMACS 2019.3 a été utilisé. La fonction de distribution radiale (RDF) des systèmes a été calculée et le nombre, la taille, le moment dipolaire et la forme des agrégats ont été analysés le long des simulations de dynamiques moléculaires. La deuxième partie du travail porte sur l'interaction des modèles d'asphaltènes avec des modèles de nanoparticules de silice. L'objectif de cette partie est d'identifier si une des sous-fractions A1 ou A2 sera préférentiellement adsorbée à la surface de la nanoparticule et dans quelles conditions. Deux modèles de nanoparticules, l'une sphérique et l'autre assimilée à une surface 2D périodique, ont été considérées. L'enthalpie de solubilité de ces nanoparticules a été calculée pour vérifier si les conditions de calcul et le champ de forces utilisé pour la silice étaient adéquats. Pour étudier l'interaction entre une molécule ou un agrégat d'asphaltènes et une nanoparticule de silice, le modèle de surface 2D périodique a été considéré. Le profil d'énergie libre a été calculé en utilisant une méthode de Umbrella Sampling permettant d'échantillonner efficacement une coordonnée de réaction.La structure moléculaire des modèles associés à la sous-fraction A1 (insoluble dans le toluène) favorise l'empilement des modèles qui ont de plus la capacité d'interagir en formant des liaisons hydrogène. Les molécules contenant des atomes d'oxygène, sous forme de groupes phénoliques et carboxyliques, ont tendance à former de grands agrégats et sont peu solubles dans le toluène. Les mélanges entre les modèles de type A1 et A2 montrent que la présence des modèles de type A2 tend à réduire la taille des agrégats, conduisant à des agrégats plus solubles. Les liaisons hydrogène sont un facteur clé de la stabilité des agrégats en solution. La distribution asymétrique des charges avec l'augmentation de la taille de l'agrégat conduit à une diminution du moment dipolaire de l'agrégat. Le calcul du paramètre de solubilité pour les modèles d'asphaltènes en général sont raisonnables aux valeurs déjà rapportées pour les sous-fractions A1 et A2. La rigidité d'un modèle affecte le nombre de façons dont il peut interagir avec une surface. Plus le modèle est rigide, plus les fluctuations des interactions sont faibles, alors que plus une molécule est flexible, plus les fluctuations seront importantes et il sera alors plus difficile d'identifier des facteurs prépondérant (en raison du plus grand nombre de conformations). Les différents solvants ont pour effet de modifier les barrières énergétiques associées à l'adsorption d'un modèle sur la surface de silice. L'adsorption des agrégats dépend de leur taille. Plus l'agrégat est grand, plus le nombre d'interactions intermoléculaires est important, ce qui se traduit par une énergie d'interaction plus attractive à la surface<br>The objective of this work is to study by molecular dynamics simulation the behavior of asphaltene subfractions A1 and A2 in solution, in the presence of a silica nanoparticle. The sub-fractions of asphaltenes A1 and A2 are obtained experimentally from a treatment of asphaltene solutions with p-nitrophenol in cumene. The work is divided into two parts. The first part deals with the behavior of the subfractions in solution in toluene and determined the computational conditions and selected the best models representing these subfractions. Then, a series of models was proposed and their behavior in heptane, THF and chloroform was characterized. In addition, the solubility parameters of each model were calculated and compared to literature values. The GROMACS 2019.3 calculation software was used. The radial distribution function (RDF) of the systems was calculated and the number, size, dipole moment and shape of the aggregates were analyzed along molecular dynamics simulations. The second part of the work deals with the interaction of asphaltene models with silica nanoparticle models. The objective of this part is to identify if one of the A1 or A2 subfractions will be preferentially adsorbed on the surface of the nanoparticle and under which conditions. Two models of nanoparticles, one spherical and the other assimilated to a periodic 2D surface, have been considered. The immersion enthalpy of these nanoparticles was calculated to check if the calculation conditions and the force field used for silica were adequate. To study the interaction between an asphaltene molecule or aggregate and a silica nanoparticle, the periodic 2D surface model was considered. The free energy profile was calculated using an Umbrella Sampling method to efficiently sample a reaction coordinate.The molecular structure of the models associated with the A1 subfraction (insoluble in toluene) favors the stacking of the models, which also have the ability to interact by forming hydrogen bonds. Molecules containing oxygen atoms, in the form of phenolic and carboxylic groups, tend to form large aggregates and are poorly soluble in toluene. Mixtures between A1 and A2 type models show that the presence of A2 type models tends to reduce the size of the aggregates, leading to more soluble aggregates. Hydrogen bonding is a key factor in the stability of aggregates in solution. The asymmetric charge distribution with increasing aggregate size leads to a decrease in the dipole moment of the aggregate. The calculation of the solubility parameter for asphaltene models in general are reasonable at the values already reported for the A1 and A2 subfractions. The stiffness of a model affects the number of ways it can interact with a surface. The more rigid the model, the smaller the fluctuations in interactions, whereas the more flexible a molecule is, the larger the fluctuations will be and it will then be more difficult to identify overriding factors (due to the larger number of conformations). The different solvents have the effect of modifying the energy barriers associated with the adsorption of a model on the silica surface. The adsorption of aggregates depends on their size. The larger the aggregate, the greater the number of intermolecular interactions, resulting in a more attractive interaction energy at the surface<br>El objetivo de este trabajo es estudiar mediante simulación de dinámica molecular el comportamiento de las subfracciones de asfaltenos A1 y A2 en solución, en presencia de una nanopartícula de sílice. Las subfracciones de asfaltenos A1 y A2 se obtienen experimentalmente a partir de un tratamiento de soluciones de asfaltenos con p-nitrofenol en cumeno. El trabajo se divide en dos partes. La primera parte se refiere al comportamiento de las subfracciones en solución en tolueno y permitió determinar las condiciones de cálculo y seleccionar los mejores modelos que representan estas subfracciones. A continuación, se propuso una serie de modelos y se caracterizó su comportamiento en heptano, THF y cloroformo. Además, se calcularon los parámetros de solubilidad de cada modelo y se compararon con los valores de la literatura. Se utilizó el software de cálculo GROMACS 2019.3. Se calculó la función de distribución radial (RDF) de los sistemas y se analizó el número, el tamaño, elmomento dipolar y la forma de los agregados a lo largo de las simulaciones de dinámica molecular. La segunda parte del trabajo trata de la interacción de los modelos de asfaltenos con los modelos de nanopartículas de sílice. El objetivo de esta parte es identificar si una de las subfracciones A1 o A2 se adsorbe preferentemente en la superficie de la nanopartícula y en qué condiciones. Se consideraron dos modelos de nanopartículas, uno esférico y otro asimilado a una superficie periódica 2D. Se calculó la entalpía de inmersión de estas nano-partículas para comprobar si las condiciones de cálculo y el campo de fuerza utilizados para la sílice eran adecuados. Para estudiar la interacción entre una molécula o agregado de asfalteno y una nanopartícula de sílice, se consideró el modelo de superficie periódica 2D, se calculó el perfil de energía libre ivutilizando un método de Umbrella Sampling para muestrear eficazmente una coordenada de reacción. La estructura molecular de los modelos asociados a la subfracción A1 (insoluble en tolueno) favorece el apilamiento de los modelos, que además tienen la capacidad de interactuar formando enlaces de hidrógeno. Las moléculas que contienen átomos de oxígeno, en forma de grupos fenólicos y carboxílicos, tienden a formar grandes agregados y son poco solubles en tolueno. Las mezclas entre modelos de tipo A1 y A2 muestran que la presencia de modelos de tipo A2 tiende a reducir el tamaño de los agregados, dando lugar a agregados más solubles. El enlace de hidrógeno es un factor clave en la estabilidad de los agregados en solución. La distribución asimétrica de la carga con el aumento del tamaño del agregado conduce a una disminución del momento dipolar del mismo. El cálculo del parámetro de solubilidad para los modelos de asfaltenosen general son razonables en los valores ya reportados para las subfracciones A1 y A2. La rigidez de un modelo afecta al número de formas en que puede interactuar con una superficie. Cuanto más rígido sea el modelo, menores se-rán las fluctuaciones en las interacciones, mientras que cuanto más flexible sea una molécula, mayores serán las fluctuaciones y más difícil será identificar los factores dominantes (debido al mayor número de conformaciones).Los diferentes disolventes tienen el efecto de alterar las barreras energéticas asociadas a la adsorción de una plantilla en la superficie de sílice. La adsorción de los agregados depende de su tamaño. Cuanto mayor sea el agregado, mayor será el número de interacciones intermoleculares, lo que dará lugar a una energía de interacción más atractiva en la superficie

Le travail de thèse effectué a porté sur l'applicabilité et la compréhension d’un système catalytique bifonctionnel acide et hydro/déshydrogénante sur l'hydroconversion et l’hydrotraitement d'un Résidu Sous Vide. En amont de ce travail, il est rappelé qu'au-delà de 400 °C (régime thermique), la forte conversion du RSV conduit à des phénomènes indésirables de précipitation et d’instabilité, liés à l'augmentation de la polarité des asphaltènes. L’objectif de la thèse était donc de favoriser les réactions de craquage et d’hydrogénolyse à plus faible température (370 °C), grâce à la fonction acide du catalyseur, et d’étudier la nature des structures asphalteniques résultantes. Des catalyseurs modèles, de formulation NiMo, supportés sur des aluminosilicates préparés par greffage de silicium à la surface d'une alumine, ont été utilisés. Ces catalyseurs développent une acidité faible, apportée par le support. Cette acidité a été quantifiée et caractérisée sur les aluminosilicates synthétisés, comme sur le catalyseur fini. La phase hydrogénante, ainsi que la texture des solides, ont aussi été caractérisées en détail. Des catalyseurs, dont les trois paramètres précités ont pu être modifiés indépendamment, ont ainsi été obtenus.Les performances catalytiques ont ensuite été évaluées en hydroconversion d’un RSV Safaniya, en réacteur batch. Les résultats révèlent un impact limité de l’acidité sur les grandeurs globales du test. Les modifications successives des phases hydrogénantes, et l’apport de macroporosité, n’ont pas permis d’améliorer cet impact par la suite. L’analyse détaillée conduite sur les asphaltènes après conversion a mis en relief des modifications de structures moléculaires nettes. Celles-ci ont pu être illustrées via une méthode de reconstitution moléculaire. L'introduction d’acidité a ainsi favorisé les réactions de craquage des chaines aliphatiques ou naphténique des asphaltènes, sans pour autant augmenter l'aromaticité de la molécule<br>The aim of this work was to study and investigated bifunctional sulfided and acidic catalyst for the hydroconversion and the hydrotraitment of a Vacuum Residue. Upstream works have already demonstrate that high level of residue conversion, at high temperatures ( &gt; 400 °C), leads to create carbonaceous sediments (sediments), link to asphaltenes polarity and aromaticity. Thus, our objective was to promote hydrocracking reactions at lower temperatures (370 °C), by enhancing acidity of conventional sulfided catalysts. Structures of consequent asphaltenes, modified by acidity, were also studied. Model NiMo catalysts were obtained by grafting silica on the surface of alumina carriers. Characterization on carriers and sulfided catalysts reveal the improvement of a weak acidity. Hydrogenating phase and textures properties have also been characterized in this work. In the end, we have obtained catalysts with same texture, same hydrogenating power, but also different level of acidity strength. Catalytic performances were evaluated in batch reactor, for the hydroconversion reaction of a Safaniya Vacuum Residue. Results reveal no changes in hydroconversion or hydrotraitment reactions parameters with acidity. No improvement was observed by enhancing the hydrogenating power or by adding macroporosity on textures with acidic sulfided catalysts. Nonetheless, combinated asphaltenes analysis and molecular reconstructions methods have shown that acidity can modify asphaltènes structures and properties. Acidity enhances cracking reactions of aliphatic chains and naphthenic units, without improving the aromaticity of the molecules

Ce travail porte sur la compréhension des paramètres du catalyseur (texture, effet de support) permettant d’améliorer la réaction de conversion de liquéfiats de charbon. En effet, le catalyseur actuellement employé est un catalyseur du type conversion de résidu sous vide de brut de pétrole. Or ces matrices sont différentes en termes de poids moléculaires et de teneur en hétéroélément (O et N). Pour atteindre l’objectif de cette thèse, une caractérisation poussée du liquéfiat a été menée à l’aide de diverses techniques (GCxGC, HR-13C-RMN, FT-ICR/MS,…). Cette analyse détaillée du liquéfiat a mis avant son caractère fortement aromatique. Les extractions aux solvants ont permis d’isoler les asphaltènes et préasphaltènes de ce liquéfiat. Leurs analyses montrent que ces familles de composés sont de plus faible masse moléculaire que les asphaltènes des résidus pétroliers, et que leur teneur en hétéroélément est plus importante. Les tests catalytiques de conversion de liquéfiat ont été réalisés à 420°C 15MPa d’H2 pendant 8h. Ils montrent que l’augmentation de la taille de pore (mésoporeux) ainsi que l’apport d’une bimodalité du support (méso+macroporosité) permettent d’augmenter le transfert de matière et donc d’augmenter le coefficient de diffusion ce qui a pour conséquence d’améliorer le rendement en produits plus légers. Concernant la nature du support, de part sa capacité à favoriser les réactions d’HDO le TiO2 (vs Al2O3) permet de limiter la compétition entre les composés oxygénés et les composés hydrocarbonés. En conclusion, ce travail montre que plusieurs paramètres sont susceptibles d’améliorer les performances des catalyseurs de conversion des liquéfiats de charbon<br>This work focuses on the comprehension of the catalyst parameters (textural properties and support effect) that increase the yield of the coal liquid upgrading. The current in use catalyst was design for the petroleum vacuum residue conversion. However, these two feeds present different characteristics such as the average molecular weight and the amount of heteroelement (especially O and N). To reach our goal, an in-depth characterization of the coal liquid was carried out using techniques such as GCxGC, HR-13C-NMR, FT-ICR/MS. This coal liquid analysis pointed out its strong aromatic character. Extractive solvent experiments isolated the asphaltenes and preasphaltenes and their analysis show that they have a smaller average molecular weight distribution than that of petroleum asphaltenes. Catalytic experiments were carried out at 420°C, 15MPa of H2 for 8h. It shows that the increasing mesoporous size and the bimodality (meso + macroporosity) enable to raise the mass transfer thus the diffusion coefficient which enhances the yield in lighter products. The capability of TiO2 (as a support vs Al2O3) to promote HDO reaction, enables to restrain the competition between oxygen containing compounds and pure hydrocarbons. To conclude, this work demonstrates that several parameters can enhance catalyst’s performance for the coal liquid upgrading

Ce travail porte sur la compréhension du phénomène d'instabilité qui se produit dans le procédé d'hydroconversion des résidus sous vide (RSV). Au delà de 60% de conversion du RSV, l'instabilité se manifeste par un dépôt solide d'hydrocarbures lourds dans les unités industrielles de conversion des résidus, ce qui empêche d'atteindre un niveau de conversion du RSV plus élevé. L'objectif de cette thèse consiste à mieux comprendre l'influence du catalyseur utilisé dans le procédé d'hydroconversion sur l'apparition du phénomène d'instabilité. Des catalyseurs dopés au fluor et sodium ont été préparés par ajout de dopants à la surface d'un catalyseur NiMo/Al2O3 de référence. Après leur caractérisation, les catalyseurs ont été testés sur charge réelle RSV en réacteur autoclave. Les tests catalytiques ont été réalisés à haute température dans les conditions industrielles (430°C) et à plus basse température (390°C), afin de favoriser les réactions catalytiques par rapport aux réactions thermiques. Les tests catalytiques réalisés à 390 et 430°C montrent une teneur en sédiments deux fois moins importante avec le catalyseur F-NiMo, ce qui est expliqué par une amélioration de la conversion des asphaltènes. Celle-ci est expliquée par l'amélioration des réactions d'hydrogénation et de l'acidité, et par une meilleure résistance au cokage à 390°C. L'effet de la température sur la stabilité a également été étudié. Les résultats démontrent que la teneur en sédiments des effluents est deux fois supérieure pour les tests réalisés à 430°C par rapport aux tests réalisés à 390°C. Cet accroissement de l'instabilité est attribué à un caractère plus aromatique et condensé des molécules qui précipitent (asphaltènes), qui ont en conséquence une tendance accrue à s'agréger, et par la désalkylation des molécules qui stabilisent (résines).

Ce est consacré à l’élaboration et à l’étude de mélanges de type polymères/maltènes (MP) et polymères/asphaltes (AMP). Les polymères sont des copolymères à blocs de styrène et de butadiène (SBS) présentant une architecture ramifiée en étoile à quatre branches. Ils ont été partiellement hydrogénés en SBEBS grâce à l’utilisation d’un catalyseur type Ziegler-Natta. Dans les conditions expérimentales utilisées, les analyses physico-chimiques des SBEBS ont clairement montré que l’hydrogénation a été réalisée sans dégradation ni réticulation des chaînes macromoléculaires. Les mélanges, fabriqués sous agitation à l’état fondu, ont ensuite été caractérisés par rhéologie et microscopie de fluorescence. Les résultats obtenus permettent d’établir que : - selon la teneur en copolymère, les AMP présentent soit une morphologie de type émulsion soit une structure de type macroréseau, - les mélanges polymères/maltènes sont des systèmes bi-phasiques constitués par une phase de copolymère gonflé et une phase de maltènes, tandis que les mélanges polymères/asphaltes sont des systèmes tri-phasiques constitués d’une phase de copolymère gonflé, d’une phase de maltènes et d’une phase d’asphaltènes stabilisés par des maltènes. Dans tous les cas, ces effets sont la conséquence directe du gonflement du copolymère dans les mélanges. Cette étude a donc permis d’établir que la microstructure des copolymères a une influence notoire sur leur gonflement et sur les performances rhéologiques des mélanges résultants<br>A study of maltenes/polymer and asphalt/polymer blends, with two styrene-butadiene-styrene (SBS) polymers with four-branch star-like chain architecture is reported in this work. The employed polymers, with the same overall composition and distribution, were in-situ partially hydrogenated using a Nickel II Ziegler-Natta type catalyst without cross-linking or chain scission reactions. Blends were prepared by a melt mixing procedure and studied by fluorescence microscopy and rheological measurements. Results indicate that maltene/polymers blends are bi-phase heterogeneous systems with swollen polymer-rich and maltenes-rich phases, while asphalt/polymers blends are tri-phase systems with swollen polymer-rich, maltenes-rich and stabilized asphaltenes phases. In both cases, the rheological behavior of blends is mainly affected by the swollen polymer rich phase. It was confirmed that the rheological properties of PMM depend on the molecular characteristics of the copolymer such as the total molecular weight and molecular architecture, which determine the material behavior

La texture et la microtexture de precurseurs carbones de composition elementaire variee ont ete etudiees lors de la carbonisation depuis la nucleation, jusqu'a la coalescence et a la fin de la croissance des domaines orientes. Dans la 2**(e) partie, les relations roche-mere et petrole sont abordees par l'etude de la filiation kerogene-asphaltene de roche-asphaltenes d'huile. Dans la 3**(e) partie, on analyse l'influence de la biodegradation sur l'importance des domaines orientes des aspfhaltenes a partir d'une serie d'huile a biodegradation croissante. La degradation microtexturale s'accentue avec le pourcentage ou hydrocarbures aromatiques partant precocement au cours de la pyrolyse. Les asphaltenes sont affectes par les facteurs modifiant la matiere organique totale

Les activités de production des hydrocarbures sont fortement dépendantes du comportement thermodynamique des fluides produits. La précipitation d'asphaltènes, entités qui constituent les principaux composants de la fraction la plus lourde et la plus polaire du pétrole, peut conduire à la formation d'un dépôt solide. Nous avons mis en oeuvre et évalué plusieurs méthodologies expérimentales appliquées à la détermination des diagrammes de phase de fluides asphalténiques dans les conditions de haute pression et haute température. Nous avons mis au point une technique utilisant un résonateur à cristal de quartz (RCQ), capable d'identifier les conditions thermodynamiques de changement de phase, sous haute pression, dans des fluides avec une teneur faible en asphaltènes. Les données obtenues avec le RCQ ont été validées par filtration isobare et par microscopie haute pression (MHP). Les effets sur la floculation de l'ajout de gaz, des conditions thermodynamiques imposées au fluide et de la vitesse de dépressurisation ont été étudiés expérimentalement à l'aide des trois techniques susmentionnées. Les résultats obtenus par MHP sur différentes live oils suggèrent l'existence de quatre types de comportement de fluides lors d'une dépressurisation isotherme, avec dans certains cas l'apparition d'un équilibre liquide-liquide dans des conditions de températures et de pressions élevées. Enfin, nous avons établi, avec la caractérisation physico-chimique des asphaltènes obtenus (nC7) à partir des huiles mortes, que la différence d'aromaticité entre cette fraction et celle de son huile d'origine, pouvait être un indicateur utile afin d'anticiper un possible phénomène de précipitation<br>Oil production activities are strongly dependent on the phase behavior of produced fluids. The flocculation of asphaltenes, the major components of the heaviest and most polar fraction of crude oil, can lead to solids formation in several steps of oil production. In this thesis, we evaluated several methodologies applied for asphaltenes phase behavior assessment under high-pressure conditions. Among the methodologies, we had developed an apparatus based on the quartz crystal resonator (QCR), able to identify thermodynamic conditions of phase changes in pressurized fluids containing low asphaltenes content. The data obtained with the QCR were validated by isobaric filtration and high pressure microscopy (HPM) tests. Applying the three aforementioned techniques, the influence of gas addition, kinetic factors, thermodynamic conditions and the influence of depressurization rate on the onset of asphaltenes flocculation were studied. Live oils were evaluated by the HPM technique. The results from HPM suggest the existence of four phase behavior patterns for isothermal depressurization experiments, highlighting the existence of a liquid-liquid equilibrium at elevated temperatures and pressures. The physico-chemical characterization of asphaltenes extracted with n-heptane from dead oil suggests that the difference of aromaticity between this fraction and its referred oils could be a parameter to indicate possible problems of asphaltenes flocculation during the oil production

Parmi les effets stabilisant les mousses produites sans espèces tensioactives, les écoulements Marangoni jouent un rôle important. Nous avons donc mis au point une expérience permettant d’étudier ces écoulements et permettant de tester avec une grande sensibilité l’adsorption d’espèces à une interface liquide/gaz. Nous nous sommes ensuite intéressés à la moussabilité des mélanges binaires d’huiles, en l’occurrence les mélanges alcane/toluène. Même si ces espèces prises séparément ne moussent pas, le mélange des deux peut présenter une moussabilité importante. En effet, dans les mélanges considérés, la proportion des deux espèces à l’interface avec l’air n’est pas la même que celle dans le volume du mélange, les sites à l’interface liquide/gaz n’ayant pas les mêmes énergies que les sites en volume. Une modification de l’épaisseur d’un film liquide, qui se traduirait par une modification du rapport du nombre de sites accessibles par les molécules surface sur volume, est ainsi défavorisée. Enfin, nous avons étudié la moussabilité de systèmes modèles du brut contenant des asphaltènes qui sont des espèces colloïdales endogènes des bruts présentant des propriétés interfaciales connues aux interfaces eau/huile et solide/liquide. En utilisant le montage développé pour étudier l’effet Marangoni, nous démontrons qu’aux concentrations inférieures à 5wt% les asphaltènes ne s’adsorbent pas significativement aux interfaces liquide/gaz. Toutefois, nous montrons que la stabilité des mousses de mélange d’huiles est accrue par la présence d’asphaltènes : nous suggérons que cet effet résulte de la pression osmotique induite dans les films liquides par les agrégats colloïdaux d’asphaltènes<br>Knowing that the Marangoni effect plays a major role in stabilizing foams produced without surfactant, we have developed an innovative setup in order to study quantitatively Marangoni flows at the surface of a liquid. Moreover, this experiment provides an experimental tool that can detect the presence of surface active agents at liquid/gas interfaces with a high sensitivity. In parallel, we have studied the foamability of binary mixtures of alkane and toluene. Indeed, even though these oils taken separately do not foam, the binary mixture can have a high foamability. In fact, the proportion of the two species at the liquid/gas interface is not the same because the sites at the surface do not have the same energies than the sites in volume. A modification of the thickness of a liquid film composed of a binary mixture would result in a modification of the ratio of the number of sites accessible by molecules surface-to-volume. Such a thinning is thus disadvantaged. Finally, we have studied the foamability of model systems of crude oil, namely solutions composed of asphaltenes dispersed in oil mixtures. Asphaltenes are endogenous colloidal species of crude oils with well-known interfacial properties at water/oil and solid/oil interfaces. Using the setup developed to study the Marangoni effect, we have shown that at concentrations not exceeding 5wt% of asphaltenes, the latter do not adsorb significantly at oil/gas interfaces. However, we demonstrate that the stability of the alkane/toluene foams is increased by the presence of asphaltenes: we suggest that this effect results from the osmotic pressure induced in the liquid films by the colloidal aggregates of asphaltenes

Au cours du procédé de fabrication des disques de freins aéronautiques, les industriels utilisent une huile aromatique qui se charge en divers composés chimiques et perd progressivement ses propriétés d’intérêt. Après plusieurs cycles d’utilisation, elle est alors évacuée et incinérée, ce qui représente une empreinte carbone non-négligeable ainsi que des coûts de consommation importants. L’objectif de ce projet est donc de proposer un procédé permettant le traitement de l’huile en vue de son recyclage.En premier lieu, plusieurs méthodes ont été développées afin de caractériser l’huile à divers stades de pollution. D'une part, des analyses par chromatographie gazeuse couplée à de la spectrométrie de masse ont permis de détecter la présence d’hydrocarbures aromatiques polycycliques (HAP), solubilisés dans l’huile. D’autre part, des mesures de viscosité ont mis en évidence l’augmentation continue de ce paramètre au cours de la pollution l’huile. Cet accroissement s’est avéré être principalement dû à l’accumulation d’un autre type de composés, des asphaltènes, présents en suspension dans le milieu. La concentration de ces objets a été déterminée à partir d’extraits secs. La mise en œuvre de diffusion par rayons X aux petits angles (SAXS) a par ailleurs permis de déterminer la taille de ces nanoobjets.Compte tenu des caractéristiques distinctes des deux catégories de polluants, divers procédés de séparation ont été sélectionnés. Pour la séparation des asphaltènes, la mise en œuvre d’une filtration membranaire (ultrafiltration) ou d’un couplage précipitation - microfiltration a été envisagée. En ce qui concerne l’élimination des HAP, la filtration membranaire (nanofiltration), la distillation sous vide et l’extraction par CO2 supercritique ont été ciblées. Pour réaliser ces études, une approche méthodologique a été proposée, couplant essais expérimentaux, modélisation thermodynamique et simulation numérique pour l’extraction au CO2 supercritique et la distillation. La filtration membranaire a, quant à elle, été étudiée expérimentalement et à diverses échelles.Les essais de filtration membranaire ont montré la possibilité de retenir les asphaltènes par la mise en œuvre d’ultrafiltration. Cependant, il convient de trouver les paramètres opératoires permettant d’atteindre des performances acceptables à l’échelle industrielle (seuil de filtration, conditions de pression et température, stade de pollution de l’huile…). La précipitation des asphaltènes avant filtration peut également être envisagée pour faciliter leur séparation. Les résultats montrent que la mise en contact de l’huile avec un alcane de type n-heptane permet la formation de précipités, séparables ensuite par microfiltration.En ce qui concerne la séparation des HAP, les résultats de simulation prévoient une séparation efficace de ces composés par distillation sous vide. En effet, pour une huile polluée composée de 5% massique en HAP, ce procédé permet l’obtention d’une huile régénérée avec une teneur inférieure à 1%. L’extraction au CO2 supercritique s’avère également prometteuse pour réaliser cette séparation. L’étude souligne cependant une faible solubilité des HAP les plus lourds dans ce solvant, ce qui devra être considéré si ce procédé est choisi. 60% des HAP contenus dans l’huile polluée sont tout de même extraits par le CO2 dans les conditions étudiées. Enfin, quel que soit le seuil de filtration mis en œuvre, y compris la nanofiltration, la séparation membranaire ne permet pas l’élimination des HAP<br>In the manufacturing process of aircraft brake discs, an aromatic oil is employed, where it is charged into various chemical compounds and subsequently undergoes a gradual loss of its properties. Following several cycles of use, the oil is then evacuated and incinerated, representing a considerable carbon footprint and high consumption costs. The objective of this project is to propose a process for the recycling of oil in order to reuse it in the process.In the initial phase of this study, several analytical methods were used for the characterization of oil in its various stages of contamination. First, gas chromatography and mass spectrometry (GC-MS) were employed to detect the presence of polycyclic aromatic hydrocarbons (PAHs), which are solubilized in oil. Then, viscosity measurements have demonstrated that this parameter exhibits a continuous increase during the process of oil pollution. This increase is mainly due to the accumulation of another type of compound, namely asphaltenes, which are present in suspension in the oil. The concentration of these objects was determined by using a dry extracts method. The application of small- angle X-ray diffraction (SAXS) has also permitted the determination of the dimensions of these nano-objects.In view of the distinctive characteristics of the two classes of pollutants, different separation processes were selected for each class. For the separation of asphaltenes, the implementation of membrane filtration (ultrafiltration) or precipitation coupling with microfiltration was considered. In order to achieve the removal of PAH, the following techniques were considered: nanofiltration, vacuum distillation, and solvent extraction (supercritical fluid). To perform these studies, a methodological approach was proposed, combining experimental tests, thermodynamic modeling, and numerical simulation for supercritical CO₂ extraction and distillation. Membrane filtration has been the subject of exclusive experimental study at various scales.Membrane filtration tests have demonstrated the possibility of retaining asphaltenes by ultrafiltration. However, it is necessary to find the operating parameters that allow acceptable performances on an industrial scale (molecular weight cut off, pressure and temperature conditions, stage of oil pollution...). The precipitation of asphaltenes prior to filtration may also be considered as a means of facilitating their separation. The results demonstrate that the contact of the oil with an n-heptane alkane allows the formation of precipitates, which can be effectively separated by microfiltration. Regarding PAHs separation, the simulation results demonstrate the efficacy of vacuum distillation as a method for the separation of PAHs. Indeed, for a polluted oil composed of 5% by mass in PAH, this process allows the production of a regenerated oil with a PAH concentration of less than 1%. Furthermore, supercritical CO₂ extraction is a promising method for achieving this separation. However, the study indicates that heavier PAHs have low solubility in this solvent, which should be considered if this process is selected. Nevertheless, 60% of the PAHs present in the polluted oil are extracted by CO₂ under the investigated conditions. Finally, regardless of the filtration scale employed, including nanofiltration, membrane separation is unable to effectively remove PAHs.This study allows an evaluation of the effectiveness of targeted separation processes for the regeneration of polluted oil. The results demonstrate that a combination of processes is required for the separation of the two classes of pollutants. The selection of the final process remains a future decision. In addition to the technological feasibility, a number of other criteria must be considered, including the required quality of the oil, the costs of processing, the ease of operation, and so forth

Asphaltenes are the heaviest components of petroleum and bitumen consisting of a complex mixture of heteroaromatic substances that have been associated with various deposition problems in both upstream and downstream sectors of the petroleum industry. This thesis describes characterisation of asphaltenes from a variety of sources and geographical areas using FTIR, NMR, as well as selective chemical degradation methods in combination with GC/MS & GC/IRMS with the aim of understanding how their compositions vary with source and geochemical history. Asphaltenes were observed to co-precipitate with substances such as waxes that are components of the maltene fraction. Quantitative removal of the co-precipitated substances requires Soxhlet extraction of the asphaltenes for several hours. The extraction time was found to vary with different asphaltenes. The so-called occlusion or physical entrapment of biomarkers in the cage-like structure of the asphaltenes is more than likely a consequence of the co-precipitation of the waxes. Analysis of mid-infrared spectra of the asphaltenes revealed that petroleum asphaltenes consist predominantly of aliphatic moieties bonded to condensed aromatic structures with relative proportions of aromatic carbon in range of 30 to 40% for non-biodegraded petroleum asphaltenes as revealed by 13C NMR. Biodegraded asphaltenes are less aromatic with relative aromatic carbon being 27% or less although the aromatic moieties tend to have relatively greater degree of condensation than asphaltenes from ono-degraded oils . Although n-alkyl and iso-alkyl groups are the dominant aliphatic moieties, naphthenic groups, mainly in form of homohopanoids and steroids, are significantly present. Oxygen functionalities are mainly in form of hydroxyl, ether, ester, and carboxyl as well as conjugated ketone groups. Ester groups were detected only in coal and black shale asphaltenes. Carboxyl groups were detected in all the asphaltenes irrespective of source and geographical region, although they were particularly prominent in black shale and coal asphaltenes even at a relatively high rank of Ro = 1.5%. Nitrogen functionalities were present as pyridinic and pyrrolic heteroaromatic systems in addition to tertiary aromatic amines. With increasing thermal stress, asphaltenes were observed to evolve towards an equilibrium structure or composition in which aromatic moieties become dominant over aliphatic moieties as a result of increasing condensation and dealkylation. Distribution of alkyl moieties shifts towards increasing proportions of the lower molecular weight homologues with increasing thermal maturity. The thermal stress also results in loss of oxygen functionalities mainly from ester and carboxyl groups. At the molecular level, isomerisation of bound hopanoids and steroids to form an equilibrium composition was observed with increasing maturity. However, while isomerisation of bound hopanoids in asphaltenes appear to be in phase with the corresponding isomerisation of hopanes in the maltene fraction, the isomerisation of bound steroids lags significantly behind the corresponding isomerisation of the steranes in the maltenes. There is good potential in using multivariate pattern recognition tools in oil/oil correlations based on asphaltene bulk composition as measured using FTIR. Notwithstanding some misclassification, the techniques tend to correlate asphaltenes with common source. Similarly, the aliphatic moieties of asphaltenes also reflect the organic matter sources of the asphaltenes. The n-alkyl moieties from asphaltenes with common source not only show similar distributions, but also similar δ13C trends even in asphaltenes from biodegraded oils. Likewise, bound hopanoids also reflect the organic matter source such that asphaltenes with common source show similar hopanoid distributions. The aliphatic moieties therefore have good potential that may be comparable to the conventional hydrocarbon-based biomarkers in oil/oil correlations. In general, the composition of asphaltenes is controlled by the source organic matter and its thermal evolution. The effect of biodegradation is not yet completely understood but, with the exception of steroids, it does not appear to affect the aliphatic composition of the asphaltenes. There is therefore a significant potential in using asphaltenes in discrimination/correlation of oils particularly where the hydrocarbons in the maltene fraction are lost to biodegradation.

Made available in DSpace on 2016-08-19T12:56:39Z (GMT). No. of bitstreams: 1 Maria do Socorro Garreto.pdf: 7283583 bytes, checksum: 2b71ac789d5be27c5154d61dd9dc98cc (MD5) Previous issue date: 2006-05-10<br>The crude oil can be understood as a mixture sufficiently polydisperse where its diverse components form a dispersion and/or solution whose original state can be modified in function of variations of temperature, pressure and composition causing, for example, the formation of organic deposits. The asphaltene constitutes heavy fractions of oils with great capacity for precipitation and consequent deposition. Better understanding of the asphaltenes behavior is essential to reduce the negative impacts caused by these fractions in petroleum production and processing. An important subject is the relation between the asphaltenes stability in the oils and the measurements of asphaltenes onset precipitation, which represent the minimum amount of a flocculent (n-alkane of low molar mass) necessary to initiate the formation of the precipitated ones in the oils. These measurements, in general, are executed in different conditions against the found ones during the production, and are found also significant errors for oils with low amounts of asphaltenes and with particles in suspension. Distinct interpretations in relation to the precipitation phenomenon are still verified when comparing the results between diverse techniques. In this work, the results of different techniques in the determination of the asphaltenes onset precipitation have been evaluated by optical microscopy, viscosimetry and impedance spectroscopy in ten samples of Brazilian crude oils with different characteristics. The results of precipitation onset also had been related with the asphaltenes stability in the pure oils and mixtures of oils. The oil samples had been assigned P1-P10, A and B. The precipitation onset was induced by the addition of heptane in the oil and the toluene oil (2:1) mixture. The results showed good agreement with the values of precipitation onset for the three evaluated techniques, indicating that the flocculation and precipitation represent the same phenomenon. The addition of the toluene provoked a displacement of the asphaltene onset precipitation point strengthening the influence of the aromaticity in the solubilization of the asphaltenes. It was still observed that the stability of the asphaltene in the oil depends on a relation between all the physico-chemical parameters, however parameters such as resins and aromatics exert a bigger influence on the stability. The study in oil mixtures had indicated that the precipitation onset is not a parameter that can be used exclusively as indicative of asphaltenes stability.<br>O petróleo pode ser compreendido como uma mistura bastante polidispersa em que, seus diversos componentes formam uma dispersão e/ou solução cujo estado original pode ser alterado em função de variações de temperatura, pressão e composição, acarretando, por exemplo, a formação de depósitos orgânicos. Os Asfaltenos constituem frações pesadas de petróleos com grande capacidade para a precipitação e conseqüente deposição pelas mudanças no equilíbrio de fases da mistura. Uma melhor compreensão do comportamento dos asfaltenos é essencial para reduzir os impactos negativos causados por estas frações na produção e processamento do petróleo. Um assunto importante e também bastante discutível é a relação entre estabilidade dos asfaltenos nos petróleos e as medidas de início de precipitação dos asfaltenos, que representa a quantidade mínima de um floculante (n-alcano de baixa massa molar) necessária para iniciar a formação dos precipitados nos petróleos. Essas medidas, em geral, são executadas em condições distintas às encontradas durante a produção, e também, verificam-se erros bastante significativos para petróleos com baixos teores de asfaltenos e que apresentam partículas em suspensão. Neste trabalho avaliaram-se os resultados obtidos a partir de diferentes técnicas para a determinação do inicio de precipitação dos asfaltenos, seja a microscopia ótica, viscosimetria e espectroscopia de impedância, para dez amostras de petróleos brasileiros com características diferentes. Os resultados de início de precipitação foram também relacionados com a estabilidade dos asfaltenos nos petróleos puros e em misturas de petróleos. As amostras de petróleos foram designadas P1-P10, A e B. O início de precipitação foi induzido pela adição de n-heptano no petróleo e na mistura petróleo tolueno (2:1). Os resultados revelaram uma boa concordância nos valores de início de precipitação para as três técnicas avaliadas indicando que a floculação e precipitação representam o mesmo fenômeno. A adição do tolueno provocou um deslocamento do ponto de início de precipitação dos asfaltenos reforçando a influência da aromaticidade na solubilização dos asfaltenos. Observou-se ainda que a estabilidade dos asfaltenos no petróleo depende de uma relação entre todos os parâmetros físico-químicos, entretanto os parâmetros resinas e aromáticos exercem uma maior influência sobre a estabilidade. Os resultados obtidos com as misturas dos petróleos indicaram que o início de precipitação não é um parâmetro que possa ser empregado, exclusivamente, como indicativo da estabilidade dos asfaltenos em misturas.

Le but de ce travail est de fournir des informations qui peuvent aider à clarifier le mécanisme par lequel se produit la précipitation d’asphaltènes afin d'optimiser les modèles qui prédisent ce phénomène. Premièrement, la composition chimique des fractions aromatiques et saturées est analysée au regard à la stabilité des asphaltènes dans le brut. Plus précisément, la composition SARA de différents bruts vénézuéliens est corrélée au seuil de floculation des asphaltènes. Nos résultats mettent en évidence que les saturées, semblables aux résines, ont un effet significatif sur la stabilité des asphaltènes dans le brut. Deuxièmement, la teneur en Ni et V dans les asphaltènes et leurs sous fractions A1 et A2 a été déterminé par spectroscopie d'émission atomique avec plasma inductif. Les données expérimentales établissent que A1 a une concentration en V et en Ni supérieure à celle de A2, quelque soit la stabilité des bruts. Nous interprétons ces données comme l’illustration d’interactions fortes, telles que des liaisons covalentes entre pétroporphyrines et les molécules d’asphaltènes. Finalement, un dispositif haut pression est utilisé pour détecter visuellement la pression seuil de floculation d'un système modèle correspondant à une solution d’asphaltènes dans un mélange toluène/heptane/CO2. Les résultats confirment, pour ces systèmes gazés, que les augmentations de pression conduisent à une augmentation de la solubilité des asphaltènes et que pour la température il y a deux régimes opposés. Le premier correspond à une diminution de la stabilité du fluide avec l’augmentation de la température et le second, passé une valeur seuil proche de 80°C, conduit au phénomène inverse<br>The purpose of this work is to provide information that can help in clarifying the mechanism by which asphaltene precipitation occurs in order to optimize the models that predict the phenomenon. The study is divided into three chapters. In the first one, the constituents of aromatic and saturate fractions of some Venezuelan crude oils were associated with the asphaltenes stability. SARA composition was correlated with asphaltene flocculation onsets and the results showed that saturates, similar to resins, have a significant effect on the flocculation process of the asphaltenes. In the second chapter, the concentration of Ni and V was determined in asphaltenes and their fractions A1 and A2. The samples were analyzed using inductively coupled plasma atomic emission spectrometry and elemental combustion analysis. Results show that A1 presents higher Ni and V concentrations than A2, in both stable and unstable crude oils. These results can be explained by strong interactions, such as covalent bonds between the petroporphyrins and the asphaltene molecules. In the final section, the asphaltenes phase envelopes were obteined for a system consisting of asphaltene in a mixture toluene/heptane/CO2. The temperature ranges 10-150 °C with varying concentrations of CO2 between 10 and 20 wt%. The experimental results confirm that increase of pressure leads to increase of solubility of the asphaltenes in the medium. Also, there are two temperature regimes having opposite trends. First, the solubility of the asphaltenes increases with the temperature, then after a threshold value of 80 °C, the stability is getting worse with the temperature