Dissertationen zum Thema „Hydrates de gaz naturel – Additifs“
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Abdallah, Mohamad. „Caractérisation multi-échelles des hydrates de gaz formés en présence d'additifs anti-agglomérants“. Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0048.
Der volle Inhalt der QuelleIn the context of oil production, the formation of gas hydrates can lead to the formation of deposits, the clogging of lines and the interruption of oil and/or gas production. Hydrate formation can therefore have a strong economic impact. To ensure production without the risk of production shutdown, different strategies are adopted. A common strategy involves the production outside the hydrate zone by injection of thermodynamic additives (THIs), for example. However, the displacement of hydrate stability conditions by THIs requires the injection of massive doses of additive with high environmental and economic costs. Another production strategy, in the hydrate zone, consists of injecting so-called low dose inhibitors (LDHI): kinetic inhibitors (KHIs) or anti-agglomerant additives (AAs). For deep offshore oil fields, only the injection of AAs is relevant. These additives do not block the formation of hydrates but prevent their agglomeration and disperse the crystals formed in the production fluids. The development of AAs and the validation of their applications on production fields require an in-depth investigation of their impacts on real production systems (dispersion of crystals in pipes, the size of crystals in the continuous phase, the transportability of slurries, etc…).êTo provide a better understanding of the impact of commercial AAs on the formation of hydrates, a multidisciplinary and multi-scale approach was adopted. The formation of natural gas hydrates was first carried out in the laboratory by reproducing oil production conditions with industrial systems under operational conditions with three different AAs. On the macroscopic scale, the slurries of crystals produced under stirring in the reactors highlight effects dependent on the AA used. They impact differently the kinetics of hydrate formation, the rate and speed of crystal growth as well as their state of dispersion. Without stirring, these AAs additives affect the morphology and control the growth of crystals and the phase in which they will grow. A hydrate transfer cell was then designed to sample of hydrate slurries formed in the reactors under conditions close to industrial reality (with stirring, high pressure, low temperature). The transferred hydrate slurries were then analyzed by X-ray microtomography using a method developed during this work. On the microscopic scale, the state of dispersion of the hydrate grains was assessed for all transferred samples and information was obtained on the size of the dispersed hydrate grains, their shape and their sedimentation in the organic phase. At the molecular scale, in-situ analyzes were carried out by Raman spectroscopy on methane hydrates formed in the presence of the three AA additives. These tests highlighted the distribution of hydrates in the organic phases (gas and condensate). Observations by optical microscopy reveal hydrate morphologies comparable to those obtained in the presence of AAs additives in the reactors
Ricaurte, Fernandez Marvin José. „Séparation du co2 d’un mélange co2-ch4 par cristallisation d’hydrates de gaz : influence d’additifs et effet des conditions opératoires“. Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3031/document.
Der volle Inhalt der QuelleThe separation of CO2 from a gas mixture by crystallization of gas hydrates is a process that could eventually provide an attractive alternative to the conventional techniques used for CO2 capture. The aim of this thesis was to evaluate the potential of this "hydrate" process to separate CO2 from a CO2-CH4 gas mixture, rich in CO2. We have studied in particular the selectivity of the separation toward CO2 and the hydrate crystallization kinetics. The effects of thermodynamic and kinetic additives (and some additive combinations) on these two parameters for different operating conditions (pressure, temperature, concentrations) were evaluated. Hydrate formation and dissociation experiments were performed in "batch mode” in a high pressure reactor, and with an experimental pilot rig designed and built entirely during this thesis. A semi-empirical model was also developed to estimate the water to hydrate conversion and the composition of the different phases (hydrates, liquid and vapor) at equilibrium. The results show that the combination of sodium dodecyl sulfate (SDS) used as a kinetic promoter, with tetrahydrofuran (THF) used as a thermodynamic promoter, provides interesting results in terms of both the amount of hydrates formed and the hydrate formation kinetics. The selectivity of the separation toward CO2 remains too low (an average of four CO2 molecules trapped in the hydrate structure for one of CH4) to consider using this "hydrate" process on a larger scale to separate CO2 from such a gas mixture
Cingotti, Béatrice. „Étude du mécanisme d'action d'une famille de copolymères inhibiteurs cinétiques susceptibles de modifier la cristallisation des hydrates de méthane“. Grenoble INPG, 1999. https://theses.hal.science/tel-01351384.
Der volle Inhalt der QuellePic, Jean-Stéphane. „Étude du mécanisme d'action d'un inhibiteur cinétique sur la cristallisation de l'hydrate de méthane“. Grenoble INPG, 2000. https://theses.hal.science/tel-00820320.
Der volle Inhalt der QuellePic, Jean-Stéphane. „Etude du mécanisme d'action d'un inhibiteur cinétique sur la cristallisation de l'hydrate de méthane“. Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2000. http://tel.archives-ouvertes.fr/tel-00820320.
Der volle Inhalt der QuelleSales, Silva Luiz Paulo. „Procédé de séparation par formation sélective d'hydrates de gaz pour la valorisation du biogaz“. Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLY021.
Der volle Inhalt der QuelleBiogas represents an alternative path to fossil energies. It is composed mainly by methane and carbon dioxide. This couple must be separated in a gas separation process. In recent years, the new process based on gas hydrate formation (GSHF) has taken special attention in academic community. Besides, the use of thermodynamic promoters can increase the efficiency of the process. Since GSFH is based on phase transition phenomenon, knowledge about phase equilibria is essential. In this project, we have selected and studied four thermodynamic promoters (tretrabutylammonium bromide / TBAB; tetrabutylphosphonium bromide / TBPB; tributylphosphine oxide / TBPO; tetrahydropyran / THP) that have potential to improve GSFH process of biogas in terms of stability gain (less energy consumption), kinetics and selectivity. One part of this project consisted in determining the gas hydrate equilibrium conditions involving these promoters and the different gas phases (CO2, CH4 and simulated biogas). Differential scanning calorimetry (DSC) methods were applied to measure the phase transition temperatures. Therefore, new phase equilibrium data were determined for the promoter/gas hydrate systems. In the second part of the project, we carried out quantitative measurements in an instrumented reactor in order to evaluate the GSFH process for upgrading biogas. Each promoter was evaluated in kinetics and thermodynamics aspects, such as crystal growth rate, amount of gas trapped into the hydrate phase, and selectivity. The optimization of the hydrate formation / dissociation cycle showed excellent results in terms of kinetics improvement
Sales, Silva Luiz Paulo. „Procédé de séparation par formation sélective d'hydrates de gaz pour la valorisation du biogaz“. Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLY021/document.
Der volle Inhalt der QuelleBiogas represents an alternative path to fossil energies. It is composed mainly by methane and carbon dioxide. This couple must be separated in a gas separation process. In recent years, the new process based on gas hydrate formation (GSHF) has taken special attention in academic community. Besides, the use of thermodynamic promoters can increase the efficiency of the process. Since GSFH is based on phase transition phenomenon, knowledge about phase equilibria is essential. In this project, we have selected and studied four thermodynamic promoters (tretrabutylammonium bromide / TBAB; tetrabutylphosphonium bromide / TBPB; tributylphosphine oxide / TBPO; tetrahydropyran / THP) that have potential to improve GSFH process of biogas in terms of stability gain (less energy consumption), kinetics and selectivity. One part of this project consisted in determining the gas hydrate equilibrium conditions involving these promoters and the different gas phases (CO2, CH4 and simulated biogas). Differential scanning calorimetry (DSC) methods were applied to measure the phase transition temperatures. Therefore, new phase equilibrium data were determined for the promoter/gas hydrate systems. In the second part of the project, we carried out quantitative measurements in an instrumented reactor in order to evaluate the GSFH process for upgrading biogas. Each promoter was evaluated in kinetics and thermodynamics aspects, such as crystal growth rate, amount of gas trapped into the hydrate phase, and selectivity. The optimization of the hydrate formation / dissociation cycle showed excellent results in terms of kinetics improvement
Mendes, Melchuna Aline. „Experimental study and modeling of methane hydrates cristallization under flow from emulsions with variable fraction of water and anti-agglomerant“. Thesis, Lyon, 2016. http://www.theses.fr/2016EMSE0811/document.
Der volle Inhalt der QuelleCrystallization of hydrates during oil production is a major source of hazards, mainly related to flow lines plugging after hydrate agglomeration. During the petroleum extraction, oil and water circulate in the flow line, forming an unstable emulsion. The water phase in combination with light hydrocarbon components can form hydrates. The crystallization of hydrates has been extensively studied, mainly at low water content systems. However, as the oil field matures, the water fraction increases and can become the dominant phase, a system less known in what concerns hydrate formation. Actually, several techniques can be combined to avoid or remediate hydrate formation. Recently, a new class of additives called Low Dosage Hydrate Inhibitor (LDHI) started to be studied, they are classified as Kinetic Hydrate Inhibitors (KHI-LDHI) and Anti-Agglomerants (AA-LDHI).This work is a parametric study about hydrate formation from emulsion systems ranging from low to high water content, where different flow rates and the anti-agglomerant presence were investigated. The experiments were performed at the Archimède flow loop, which is able to reproduce deep sea conditions. The goal of this study is enhancing the knowledge in hydrate formation and comprehending how the dispersant additive acts to avoid agglomeration. For this matter, it was developed a crystallization topological model for the systems without and with additive. A technique to determine the system continuous phase and a mechanism of the anti-agglomerant action from the chord length measurements were also proposed
Nguyen, Hong Duc. „Dissociation des bouchons d'hydrates de gaz dans les conduites pétrolières sous-marines“. Saint-Etienne, EMSE, 2005. http://tel.archives-ouvertes.fr/tel-00009985.
Der volle Inhalt der QuelleNatural gas hydrates plugs cause problems during drilling, well operations, production, transportation and processing of oil and gas. Especially, it is a very serious problem in off-shore oil transportation where low temperature and high pressure become more and more favourable to gas hydrate formation as the new production wells are more and more deeper. Up to now, although many studies have been developed concerning the possibility of preventing pipe plugging, there is limited information in open literature on hydrate plugs dissociation and all models in literature are numerically complicated. In this study, hydrate plugs are formed from water in n-dodecane mixture with addition of a dispersant E102B in two different experimental apparatus in order to obtain hydrates plugs with different sizes (diameter of 7, 10. 75 and 12 cm). Then, the plugs are dissociated by the method of two-sided depressurisation. In this paper, we propose a numerical model which describes the dissociation of gas hydrate plugs in pipelines. The numerical model, which is constructed for cylindrical coordinates and for two-sided pressurisation, is based on enthalpy method. We present also an approximate analytical model which has an average error 2. 7 % in comparison with the numerical model. The excellent agreement between our experimental results, literature data and the two models shows that the models give a good prediction independently of the pipeline diameter, plug porosity and gas. The simplicity of the analytical model will make it easier in industrial applications
Hajiw, Martha. „Étude des conditions de dissociation des hydrates de gaz en présence de gaz acides“. Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0042/document.
Der volle Inhalt der QuelleThe twentieth century has seen an important increase of the fossil energy demand, representing today 80% of world energy consumption. To meet the request, oil and gas companies are interested in new gas fields. 40% of these reserves are acid and sour gases, i.e. the percentage of carbon dioxide and hydrogen sulphide is significant, sometimes over 20% of CO2 or H2S. Natural gas production with high content of acid gases can be a challenge, due to their corrosiveness potential in pipelines in the presence of water and H2S toxicity. On another hand, as a result of world's dependence on fossil energies, the release of carbon into atmosphere is increasing and leads to climate changes. Carbon Capture and Storage (CCS) is one of the most promising ways to reduce CO2 emissions in the atmosphere. Whether in natural gas or carbon dioxide transport, water may be present. During production, transportation and processing, changes in temperature and pressure can lead to water condensation (cause of corrosion, and consequently a possible pipeline rupture), ice and/or gas hydrates formation. Hydrates are a serious flow assurance problem and may block pipelines. To avoid hydrates formation, chemical inhibitors are used. Therefore accurate knowledge of mixtures phase equilibria are important for safe operation of pipelines and production/processing facilities
Jussaume, Lisebelle. „Étude d'inhibiteurs cinétiques d'hydrates de gaz : méthodes expérimentales et modélisations numériques“. Toulouse, INPT, 1999. http://www.theses.fr/1999INPT019G.
Der volle Inhalt der QuelleBonnefoy, Olivier. „Influence de cristaux d'hydrates de gaz ou de glace sur la perméabilité d'un milieu poreux“. Saint-Etienne, EMSE, 2005. http://tel.archives-ouvertes.fr/tel-00009658.
Der volle Inhalt der QuelleThe first part is a bibliographic study. We study the conditions for thermodynamic equilibrium of the hydrates as a bulk medium and the composition of the liquid and solid phases. We then describe the basics of fluid dynamics in a porous medium. Eventually, we merge the two approaches and study the influence of the porous medium on the hydrate stability. An off-shore hydrate field (Blake Ridge) and an on-shore field (Mallik) are precisely described. The latter will be used as a reference case for subsequent numerical simulations. The second part is devoted to the experiments. Their goal is to measure the permeability of a sediment containing crystals. To get closer to natural geologic conditions, crystals are synthesized in absence of free gas. It turns out that hydrates form in a very heterogeneous way in the porous medium, which makes the measurements non representative. We believe that this result has a general character and that, at the laboratory time-scale, it is difficult, to say the least to achieve a uniform distribution of gas hydrates grown from dissolved gas. To circumvene this difficulty, we show, with a theoretical approach, that ice crystals behave much the same way as the hydrate crystals, concerning the Van der Waals forces that govern the agglomeration. This allows us to calculate the Hamaker constant of the hydrates. The second serie of experiments focuses on the permeability of a non consolidated porous medium under mechanical stress, where the pores are filled with ice crystals. Two silica beads populations are used to form a porous medium : 3 mm and 0,2 mm. With the large grains, results show two thresholds : for saturations below the lower threshold, the presence of crystals does not modify the permeability. For saturations above the upper threshold, the permeability vanishes almost completely (percolation phenomenon). Between these two limits, the permeability decreases exponentially with the saturation. With the fine grains, the permeability decreases with the same rate. The last part concerns the numerical study of the Mallik field. We write the equations describing the heat and mass transfers as a function of space and time. Then, we study a one-dimensional limiting case. This allows us to evaluate the influence of the experimentally obtained “Permeability = f(saturation)” curve on the amount of produced gas. The proposed code gives a way to assess different production scenario, as the pressure reduction enhanced by ice formation
Bourry, Christophe. „Caractérisation physique et géochimique d'hydrates de gaz d'environnements géologiques différents : apport des techniques de Diffraction X Synchrotron et de Spectroscopie Raman : contribution à l'étude de leur origine, formation et stabilité sur les marges“. Brest, 2008. http://www.theses.fr/2008BRES2043.
Der volle Inhalt der QuelleThe knowledge of the occurrence of gas hydrates in the natural environment, their physical, chemical or thermodynamical properties is essential to prevent geohazards, to anticipate their role in climate change or to develop technologies to take advantage of this energy resource. To mis purpose, this work reports a physical and chemical characterization of four natural gas hydrates from African and Norwegian margins, and from the Sea of Marmara, for documenting their origin, formation and stability. Samples from African and Norwegian margins crystallize in type I structure. This observation is in agreement with their biogenic origin. On the other hand, hydrate samples from the sea of Marmara, characterized by a thermogenic origin, exhibit a type II structure. Raman spectroscopy was also used to investigate the dissociation processes of natural gas hydrates. These results indicate that there is no preferential dissociation of large small cages. Thermodynamical modeling let us evaluate the highly variable gas hydrate stability fields in sediments from the Hakon Most Mud Volcano, whereas it let us assert that only thermogenic gas hydrates can crystallize in the sea of Marmara. In a last chapter, geochemical data obtained from porewaters, gases, and gas hydrates collected during the Vicking cruise (2006) - HERMES Program - permitted to characterize the processes controlling the fluid circulation in the Hakon Mosby Mud Volcano where gas hydrates are present in great quantity
Arla, David. „Acides naphténiques hydrates de gaz : influence de l'interface eau/huile sur les propriétés dispersantes d'un brut acide“. Pau, 2006. http://www.theses.fr/2006PAUU3002.
Der volle Inhalt der QuelleNowadays, the development of offshore oil production under increasing water depths (high pressures and low temperatures) has led oil companies to focus on gas hydrates risks. Hydrates are crystals containing gas and water molecules which can plug offshore pipelines. It has been shown that some asphaltenic crude oils stabilise water-in-oil emulsions (W/O) during several months and exhibit very good anti-agglomerant properties avoiding hydrate plugs formation. In this work, we have studied the´anti-hydraté properties of a West African acidic crude oil called crude AH. This oil contains naphthenic acids, RCOOH hydrocarbons which are sensitive to both the pH and the salinity of the water phase. The emulsifying properties of the crude AH have firstly been explored. It has been shown that heavy resins and asphaltenes are the main compounds of the crude AH responsible for the long term stability of the W/O emulsions whereas the napthenates RCOO- lead to less stable W/O emulsions. Dealing with hydrates, the crude AH exhibits moderate anti-agglomerant properties due to the presence of heavy resins and asphaltenes. However, the naphthenates RCOO- drastically increase the formation of hydrate plugs. Moreover, it has been pointed out that hydrate particles agglomeration accelerates the kinetics of hydrate formation and enhances the water/oil separation. In order to explain these behaviours, a mechanism of agglomeration by "sticking" between a hydrate particle and a water droplet has been proposed. Finally, we have developed a model which describes the physico-chemical equilibria of the naphthenic acids in the binary system water/crude AH, in order to transpose the results obtained in the laboratory to the real oilfield conditions
Gaillard, Cécile. „Cinétique de formation de l'hydrate de méthane dans une boucle de laboratoire“. Toulouse, INPT, 1996. http://www.theses.fr/1996INPT028G.
Der volle Inhalt der QuelleAlavoine, Axelle. „Modélisation du comportement des sédiments riches en hydrates de gaz via l'homogénéisation des propriétés micro-mécaniques“. Thesis, Paris Est, 2020. http://www.theses.fr/2020PESC1008.
Der volle Inhalt der QuelleGas hydrates represent an important potential energy resource, but also a risk of instability for the environment (landslides, global warming) that it is essential to control. The study of gas hydrate bearing soils, most often located on the ocean floor or in permafrost, is therefore a major challenge. The formation and dissociation of hydrates in these soils modifies the microstructure and with it the physical properties of the material. The objective of the thesis was to develop a model that could predict the behaviour of soils containing gas hydrates, initially on the scale of the conventional laboratory sample. Several multi-physical computational models applied to gas hydrate-enriched soils have already been published, but the mechanical part is still relatively underdeveloped due to the lack of experimental data and the relatively late interest shown by the mechanics' community in the subject.Based on this observation, we first focused our analysis on mechanical behaviour. The results of tests on sediments rich in methane hydrates available in the literature have been used as a basis for analyzing the effect of hydrates on the mechanical properties of a soil. In particular, the relationship between the elastic moduli of a soil and the volume fraction of hydrates was determined using an analytical homogenization calculation. However, sediments containing gas hydrate inclusions exhibit macroscopic behaviour that is far from linearly elastic. The latter is strongly related to the different physical and morphological characteristics of both matrix sediments and hydrates formed in the pore space.These observations led to the application of a numerical homogenization method based on Fast Fourier Transforms (FFTs). This method allows for the use of elastoplastic laws and complex geometries to define the microstructure components of the material to be homogenized. The results can therefore be used to determine a non-linear constitutive macroscopic model adapted to the type of sediment/hydrate composite to be simulated.The previous developments were then integrated into a finite element computation code first at the scale of the assumed homogeneous laboratory sample. Hydraulic couplings via pressures and conventional fluid flow models could therefore be integrated, as well as the solubility of methane in the aqueous phase and phase changes through a kinetic law. The thermodynamic aspect was also included. Mechanical behaviour could be defined either by analytical homogenization laws or by multi-scale calculations. The numerical homogenization calculation by FFT is carried out at the microstructure scale at Gauss integration points.These calculations were compared with laboratory test results for volume fractions of constant hydrates or for hydrate dissociation tests in soil samples. Finally, data from an exploration site were obtained from the literature and used to conduct a reservoir-scale calculation.Translated with www.DeepL.com/Translator
Vu, Quang Vinh. „Modélisation des conditions de stabilités des systèmes d'hydrates de gaz en présence des mélanges methanol-sels à l'aide d'une équation d'état d'électrolytes“. ENMP, Paris, 2001. http://www.theses.fr/2001ENMP1008.
Der volle Inhalt der QuelleFouconnier, Benoît. „Etude par calorimétrie de la formation d'hydrate de trichlorofluorométhane en émulsions : systèmes modèles pour l'étude des hydrates de gaz“. Compiègne, 2002. http://www.theses.fr/2002COMP1398.
Der volle Inhalt der QuelleKharrat, Mamdouh. „Etude des conditions de formation et de stabilité des hydrates de gaz dans les fluides de forage“. Phd thesis, École Nationale Supérieure des Mines de Paris, 2004. http://pastel.archives-ouvertes.fr/pastel-00001073.
Der volle Inhalt der QuelleLe, Quang Duyen. „Equilibre des hydrates de gaz en présence d'un mélange d'hydrocarbures gazeux“. Thesis, Saint-Etienne, EMSE, 2013. http://www.theses.fr/2013EMSE0726/document.
Der volle Inhalt der QuelleMany studies have been conducted since 1778’s to study the formation of clathrate hydrates of gas, especially under conditions of high pressure and low temperature to reproduce the conditions of oil production. My thesis mainly concerns the study of the thermodynamic of gas hydrates in presence of hydrocarbon: CO2 CH4, C2H6, C3H8, and C4H10 pure or in gas mixtures. The experimental results of this work complete the literature experimental results, were used to optimize the internal parameters related to the thermodynamic model data base GasHyDyn software.This model optimizes the parameters of Kihara and allows us to retain a second time , or to exclude a particular data set, considered as points of equilibrium , or balance points out .We finally discuss the reason for non-equilibrium of certain points, however, considered by their authors as equilibrium points. This seems kind of kinetic considerations related to a competition between gas hydrate structure to integrate during growth
Gayet, Pascal. „Formation/dissociation d'hydrates de gaz en milieu poreux : effet de la capillarité sur les conditions d'équilibre P/T“. Pau, 2005. http://www.theses.fr/2005PAUU3011.
Der volle Inhalt der QuelleGas hydrates are solid compounds that could be used as a thermal tracer for the oil or gas fields they recover. In order to do it, the P/T equilibrium conditions must be known accurately in porous medium. The work presented in this report is a contribution to the study of these conditions. Two experimental set-ups were built up. The first one, provided with a transparent cell, allows to visualize and measure equilibrium conditions of gas hydrates up to 0. 5 MPa. The second one, provided with a cell without any windows, allows to measure equilibrium conditions of gas hydrates up to 60 MPa. We checked that, in a bulk system, the use of a surfactant (SDS) accelerated hydrate formation. Their equilibrium conditions, measured and calculated, were in good agreement with literature data in the ranges 0. 2 – 0. 5 MPa for propane hydrate and 3 – 20 MPa for methane hydrate. We determined equilibrium conditions of methane hydrate, experimentally and theoretically, between 20 and 53 MPa, which completed literature data. We also checked that only mesoporous media (silica gels, clay) had an influence on equilibrium conditions of gas hydrates. They are shifted to lower temperatures and higher pressures and the smaller the mesopores, the higher the shift. On the basis of a modified van der Waals and Platteeux model, we demonstrated that shifts depended on the pore size distribution of the mesoporous systems
Fidel-Dufour, Annie. „Influence d'additifs anti-agglomérants sur l'agrégation et les propriétés de transport des hydrates de méthane dans des émulsions eau/dodécane“. Saint-Etienne, EMSE, 2004. http://tel.archives-ouvertes.fr/tel-00010236.
Der volle Inhalt der QuelleThe gas hydrates are solid compounds of clathrate type which can be formed starting from cold water and hydrocarbon gas molecules under pressure. These conditions are met in certain oil conduits and can lead to a problem of production. Indeed, the oil effluent which leaves a well of production always contains light water and hydrocarbon molecules (methane, ethane, propane) suitable from a gas hydrate. The methane hydrates are not naturally present in the layers of production because the temperature is too high (until 200°C). On the other hand, the oil fluid cools at the time of its transport in a control, either because control is localized in a particularly cold zone, or because control is underwater, by the contact with cold water. It can then create hydrates being likely to block the conduits. To prevent their crystallization, the current tendency is to couple three types of approaches : insulation of the conduits, injection of additive at the time of the critical phases, reheating of control by hot water circulation at the time of accidental stopping. This thesis takes part in the modelling of the flows after formation of hydrates. It is not thus a question of preventing crystallization but of being interested in rheology of the flow after formation of crystals. The long-term objective is to identify the origin of the transportability of the purées of hydrates under the influence of additives known as "anti-binders". It is a question of approaching the geometrical conditions of an oil flow (pilot buckles) while preserving a simple system (eau/dodécane) with for objective on the long term identifying the coupling : geometry/crystallization/influence of the additives
Bouchafaa, Wassila. „Mesure et modélisation des conditions de dissociation d'hydrates de gaz stabilisés en vue de l'application au captage du CO2“. Phd thesis, Palaiseau, Ecole polytechnique, 2011. https://pastel.hal.science/docs/00/66/71/15/PDF/final_thesis_phD.pdf.
Der volle Inhalt der QuelleThe capture and the detention of the CO2, stemming from heatings, vehicles, incineration units and various types of combustion or fermentation became a world stake. The capture of this gas by using hydrates absorption is a promising alternative. The aim of this work is to study the stability of mixed hydrates systems containing CO2 and another gas (N2, CH4 and H2) with pure water, or with an additive allowing to decrease the operating pressures: the tetrabutylamonium bromide (TBAB), in a perspective of gas separation. The experimental technique that we have used is the differential scanning calorimetry (DSC). It allowed us to measure the dissociation temperatures and enthalpies for various hydrate with pure water: N2, CH4, N2 + CO2, CH4+CO2, H2+CO2; but also semi-clathrates systems: CO2+CH4 and CO2+N2 with different mass percentages of TBAB (10, 20, 30 and 40). The last part of this thesis concerns the modelling thermodynamics of semi-clathrate systems, where we developed the particular case of the system: CH4+TBAB
Bouchafaa, Wassila. „Mesure et modélisation des conditions de dissociation d'hydrates de gaz stabilisés en vue de l'application au captage du CO2“. Phd thesis, Palaiseau, Ecole polytechnique, 2011. http://pastel.archives-ouvertes.fr/pastel-00667115.
Der volle Inhalt der QuelleTouil, Abdelhafid. „Étude par microscopie optique de la nucléation, croissance et dissociation des hydrates de gaz“. Thesis, Pau, 2018. http://www.theses.fr/2018PAUU3010/document.
Der volle Inhalt der QuelleThe nucleation, growth and dissociation of gas hydrate across a water – gas meniscus in glass capillaries are investigated by means of video-microscopy and confocal Raman spec- troscopy under controlled temperature, pressure, cooling rate and substrate wettability and geometry. Structure I and II hydrates are examined, with the following guest molecules: CO2, CH4, N2, cyclopentane, and cyclopentane + CO2. By lowering the temperature well below 0 °C, i.e., under strong subcooling, all these hydrates but the cyclopentane hydrate nucleate without forming ice on the liquid water – guest meniscus, which is rapidly covered with a polycrystalline crust. The hydrate then propagates from this meniscus as fast-growing fibers or dendrites in bulk water and as a thin polycrystalline crust, or halo, along the capillary wall. On water-wet substrates, this halo advances on the guest side of the meniscus, fed by a water layer sandwiched between the halo and glass. Symmetrically, on guest-wet (silane-treated) glass, the halo and an underlying guest layer grow on the water side of the interface. No halo is observed on intermediate-wet glass. The hydrate halo growth and morphology and the thickness of its underlying water (or guest) layer strongly depend on subcooling. Thanks to the small capillary volume and the rapid temperature descent, the metastability limit of CO2 hydrate is approached for various pressures and substrate wettabilities. The low subcooling regime is investigated as well: a novel CO2 hydrate morphology is discovered for subcoolings below 0.5 °C, which consist of a hollow hydrate crystal originating from the water – guest meniscus and advancing on the guest side along glass, fed by a thick water layer sandwiched between glass and this crystal. A new procedure is proposed to determine gas hydrate dissociation conditions in a large temperature and pressure range, including the metastable extension of the three-phase (liquid water – hydrate - guest) down to temperatures well below 0 °C. Finally, the mechanisms by which CO2 and cyclopentane synergistically act to form the structure II hydrate are discussed
Lemaire, Morgane. „Sélectivité et piégeage de mélanges gazeux dans des hydrates de gaz en présence d'impuretés : étude par spectroscopie vibrationnelle et diffraction des neutrons“. Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1R058.
Der volle Inhalt der QuelleGas hydrates are present in many natural environments like marine sediments, polar ice cores and atmospheric aerosols. They represent major challenges in the field of technical and industrial applications, ranging from the exploitation of natural gas hydrates in marine sediments to the storage and transport of natural gas in solid form. During this study, particular interest is given to the influence of minerals on the formation of gas hydrates. Aluminosilicates (sodium feldspar, calcium and potassium) are minerals that are found on Earth as well as on various astral bodies such as planets, moons, meteorites and comets. These minerals are loaded with alkalis and have a large specific surface of reaction that can influence the formation of gas hydrates. The use of neutronic diffraction, coupled with Raman spectroscopy, has shown that alkaline surrogates act as inhibitors of gas hydrate formation kinetics while modifying the selectivity of mixed hydrates. Indeed, the mobility of alkaline cations, in contact with water molecules and gaseous CO2, leads to the precipitation of carbonate, whose formation competes with that of gas hydrates. The second objective of this work was to understand the influence of these surrogates on the formation of gas hydrates under astrophysical conditions. As these data are not widely available in the literature, the main objective of this part of the study was to understand the formation of pure and mixed hydrate under very low pressure and low temperature conditions. It appears that, under these extreme conditions, it is necessary to form interfaces between different amorphous ice layers in order to allow the formation of gas hydrate
Tonnet, Nicolas. „Dissociation des hydrates de méthane sédimentaires - Couplage transfert de chaleur / transfert de masse“. Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2007. http://tel.archives-ouvertes.fr/tel-00326878.
Der volle Inhalt der QuelleDans cette étude, les transferts de masse et de chaleur ont été étudiés numériquement et expérimentalement. Un modèle numérique 2D est proposé dans lequel les transferts de chaleur et de masse gouvernent la dissociation des hydrates de méthane. Les résultats numériques montrent la présence de gradients de pression et de température au sein du milieu poreux et l'évolution de la frontière de dissociation selon le type de sédiment utilisé. Ce modèle est utilisé afin de dimensionner un dispositif expérimental de dissociation de carottes sédimentaires partiellement saturées en hydrates de méthane qui permet un suivi précis de la cinétique de dissociation.
Le montage expérimental est composé de cinq zones cylindriques de même diamètre (1/2 inch) mais de tailles différentes (pour une longueur totale de 2,6 m). Chaque zone est contrôlée en pression et en température. Chaque expérience consiste en une cristallisation d'hydrates de méthane au sein d'un milieu poreux, puis en une dissociation de ces mêmes hydrates par une méthode de contrôle de la pression à une extrémité du dispositif. La cinétique de dissociation est étudiée par le suivi de la pression dans un ballast (situé en aval du dispositif). Les résultats obtenus, via une étude paramétrique, permettent de cibler les paramètres clés de la dissociation de ces hydrates sédimentaires et d'observer leur impact sur la cinétique de dissociation. Deux régimes bien distincts de dissociation sont mis en évidence et caractérisés selon les propriétés du sédiment partiellement saturé en hydrates de méthane. Le rôle de la glace au cours de la dissociation est également étudié pour ces deux types de dissociation.
Enfin, la correspondance des résultats numériques et expérimentaux est mise en évidence par comparaison de courbes de cinétique de dissociation et de courbes d'évolution de la pression au sein du milieu poreux.
Hamed, Nejib. „Etude de la cinétique de formation des hydrates de méthane dans les fluides de forage off-shore par analyse calorimétrique différentielle haute pression“. Paris, ENMP, 2006. http://www.theses.fr/2006ENMP1402.
Der volle Inhalt der QuelleOil based drilling fluids are used in offshore drilling operations to cool and lubricate the drilling bit, to transport the cuttings to the surface and to maintain the hydrostatic pressure in the well. With the increasing depth of offshore drilling, the thermodynamic conditions (high pressure and low temperature) are favourable to the formation of gas hydrates in the water-in-oil emulsions contained in the fluids. High pressure Differential Scanning Calorimetry (DSC) is a proven technique for the study of thermodynamic equilibrium of the system gas - water - hydrate. DSC was chosen to study the kinetics of hydrate formation because it is particularly well adapted to complex dispersed media. A study was curried out at variable pressure from 11 to 40 MPa and at variable sub-cooling degree from 14 to 30 K. Hydrate formation kinetics was studied in four fluids of different compositions. Performed experiences highlight the effect of different kinetic parameters. T he use of classic models allowed representing the experimental results for low and high driving forces. Furthermore, we developed a kinetic model which combines the theory of the crystallization, the statistical aspect of nucleation and the mass balance on different components of the drilling fluid
Metais, Cyrielle. „Impact des analogues sédimentaires et de la stœchiométrie sur la métastabilité structurale, la cinétique de formation et la sélectivité moléculaire des hydrates de gaz : une étude physico-chimique combinant diffraction neutronique, spectroscopie Raman et calculs quantiques“. Electronic Thesis or Diss., Bourgogne Franche-Comté, 2021. http://www.theses.fr/2021UBFCD071.
Der volle Inhalt der QuelleGas clathrate hydrates are nanoporous crystalline solids composed of hydrogen-bonded water molecules forming cages within which gaseous guest molecules are encapsulated. Clathrate hydrates are considered to be pivotal ingredients due to their natural occurrence. They constitute a great part of the Earth’s seafloor sediments but are also involved as a byproduct in gas and oil pipeline blockages. They are also known to play a role in extraterrestrial planetary and cometary formation scenari. A very important observation common to both terrestrial and extraterrestrial clathrate hydrates is that they are predominantly and naturally formed in the presence of porous dusty ice media, possibly enriched in minerals, hydrated salts and/or sediments. The impact of these mineral impurities onto the physical-chemistry properties of clathrate hydrates (trapped-gas selectivity, thermodynamic promotion or kinetics modification) is of prime importance to track the evolution of the abundances of species taking part in the compositions of hydrate-bearing deposits on Earth and on extraterrestrial bodies. Since the hydrate morphology and distribution both depend on the medium property (chemical composition, hydrophobicity, pore space, bulk stiffness), a fundamental understanding of the hydrate selectivity, thermodynamics, formation and dissociation mechanisms onto/into mineral-like media appears to be crucial.This PhD work falls in that research context. Mixtures of CO2, N2 and CH4 gases were used to synthesize hydrates in the presence of silica beads, used as surrogates for the natural hydrate environment. Quantum chemistry calculations (in the Density Functional Theory approximation) were performed on pure CO2 and N2 hydrates: this study revealed how cage occupancy influences the structural stability of the various types of formed hydrates. Powder neutron diffraction yields the formation of these systems to be followed in situ, i.e., under pressures and temperatures mimicking natural environments. It reveals a strong influence of sedimentary particle size on the hydrate formation kinetics. Raman spectroscopy was used to study the molecular selectivity within mixed hydrates (co-including several species) in the presence of the sedimentary particles and it is showed that the latter ones also influence the selectivity, in comparison with systems formed without sedimentary surrogates. This whole set of results open up new opportunities on both applied (gas separation, kinetic promoter) and fundamental (hydrates in natural environments) aspects
Bouchemoua, Amina. „Etude du captage du CO2 par la cristallisation des hydrates de gaz : Application au mélange CO2-N2“. Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00783876.
Der volle Inhalt der QuelleLe, Ba Hung. „Formation et agglomération de particules d'hydrate de gaz dans une émulsion eau dans huile : Etude expérimentale et modélisation“. Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2009. http://tel.archives-ouvertes.fr/tel-00475562.
Der volle Inhalt der QuellePétuya-Poublan, Claire. „Étude de la stabilité, de l’occupation des cages et de la sélectivité moléculaire des hydrates de gaz par spectroscopie Raman“. Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0680/document.
Der volle Inhalt der QuelleGas hydrates are crystalline compounds consisting of water molecules forming cages within which gas molecules are encapsulated. In natural environments, gas hydrates are formed in the presence of gaseous mixtures in the ocean floor and would be involved in the formation of comets and planets. Understanding the molecular selectivity and the stability of mixed hydrates (co-including several gaseous species) is crucial and constitutes the core of this research work. With the help of Raman spectroscopy and neutron diffraction,supplemented by quantum chemistry calculations, hydrates formed from mixtures of CO, N2 and CO2 have been investigated. In addition to their astrophysical interest, these systems offer the opportunity to better understand the impact of physical-chemistry properties (dipolar moment, water solubility,adsorption on ice) on the selectivity.The formation kinetics and the vibrational signatures of the encapsulated molecules in various types of cage have been analyzed in pure CO and N2 hydrates for the first time. By varying pressure and temperature, the gaseous molecules exhibit an exceptional ability for diffusing through the cages. Molecular selectivity, structural stability and cage occupancy have been studied in the mixed hydrates CO-N2, CO-CO2 and CO2-N2. The aqueous affinity and the dipolar moment of the gas molecules trigger the selectivity of the trapped gases (preferential encapsulation of COand CO2). In addition, the nitrogen molecule acts as a kinetic promoter of the formed structure. These fundamental results open new opportunities on both applied (gas separation)and fundamental (hydrates in natural environment) aspects
Delroisse, Henry. „Effets de tensioactifs ioniques sur les interfaces et l’agglomération d’hydrates de gaz“. Thesis, Pau, 2017. http://www.theses.fr/2017PAUU3036/document.
Der volle Inhalt der QuellePressure and temperature conditions encountered in the pipelines of hydrocarbons production may be favorable to the formation of gas hydrates (crystalline compounds formed by the association of molecules of gas and water). Their agglomeration in pipelines may form plugs and lead to production shutdowns and cause significant economic losses. To prevent it, oil and gas companies use various methods and more particularly anti-agglomerant additives. Anti-agglomerants are surfactants that can adsorb at the hydrate crystals surface and keep them dispersed in a hydrocarbon phase. The objective of this thesis is to progress in the understanding of mechanisms of action of ionic surfactant to prevent the gas hydrates agglomeration. Several cationic surfactants were studied on a cyclopentane (CP) hydrate (formed at atmospheric pressure) and on a methane/propane hydrate (formed under pressure). For both hydrates, the effect of surfactants on the crystals morphology and on their wettability was investigated, and their anti-agglomerant (AA) performance was evaluated in an agitated reactor for systems at different conditions and compositions. The surfactants leading to the formation of individual crystals had the best AA performances. In order to have a good protection against the agglomeration, it is not necessary that the surfactants make the crystals oil wettable in a system where the oil phase is in excess. We showed that the modification (by the addition of salt for example) of the physicochemical environment of surfactant molecules plays an important role on their AA properties. Similarly, the modification of the structure of molecules (counter-ion nature, length of the hydrocarbon chains) affects their adsorption on the hydrate, the morphology and wettability of crystals and consequently their AA performance. The main factors identified for a good performance of a surfactant molecule are its capacity to be efficiently fixed and in a sufficient amount on the hydrate surface in order to make the hydrate crystals hydrophobic. In the case where it makes the hydrate hydrophilic, the surfactant has to strongly reduce the interfacial tension between the aqueous and oil phases and then reduce the intensity of capillary forces between hydrate particles. Lastly, we set a correlation between the observations done at the microscopic scale and the AA performance of surfactants evaluated at the macroscopic scale. This work confirms that the CP-hydrate is overall a good model for a simple evaluation of the surfactant molecules performance. However, the use of the CP-hydrate has some limitations to conduct studies at high subcooling and watercut
Taleb, Farah. „Etude du comportement mécanique de sédiments argileux contenant des hydrates de gaz à partir de mesures in situ Hydromechanical properties of gas hydrate‐bearing fine sediments from in situ testing, in Journal of Geophysical Research: Solid Earth 123(11), November 2018“. Thesis, Brest, 2019. http://www.theses.fr/2019BRES0114.
Der volle Inhalt der QuelleGas hydrates (GH) are composed of gas molecules, often methane, trapped in a lattice of hydrogen-bonded water molecule. They are found in sediments of continental margins and permafrost, lakes and inland seas, where their stability conditions (high pressure and low temperature) are met. GH are considered as a potential energy resource but furthermore as a potential submarine geohazard and source of greenhouse gases. It is essential to understand the consequences of the presence of these metastable components on the geo-mechanical properties of their host sediment (GHBS). Ifremer has conducted several oceanographic campaigns aiming to assess such geohazard in an area of the deep-water Niger Delta, characterised by hydrates which formed in high gas flux environments in clayey sediment. The database is composed of in-situ acoustic, geotechnical, pore-pressure dissipation measurements, as well as cores and seismic profiles.The PhD work exploited the dataset with the aim of understanding the effect of GH content, morphology and distribution on the mechanical and hydraulic properties of the GHBS. This rare field study revealed that marine GH-bearing clays have a contractive behaviour upon shearing, which contrasts with the dilative behaviour of sandy GHBS often discussed in litterature. Alternatively, different morphologies of GH have been linked with different features of the mechanical behaviour of GHBS. For high GH saturtion (> 10%), the hydraulic diffusivity of the GHBS was observed to increase with increasing GH content, which was linked to fractures or decrease in compressibility. A new simple constitutive model based on “equivalent skeleton void ratio” was used in order to simulate the mechanical behaviour of GHBS.Preliminary results show that only one additional parameter related to the morphology of hydrate is necessary to correctly simulate the mechanical behaviour of GHBS
Perrin, Amandine. „Contribution à l'étude du stockage du méthane par adsorption“. Nancy 1, 2004. http://www.theses.fr/2004NAN10125.
Der volle Inhalt der QuelleNatural gas, which methane is the main component, is an alternative fuel. It is abundant and has clean burning characteristics; however its storage is difficult due to its very low density. Two storage routes were investigated. Methane adsorption was studied in optimized microporous carbons. They were prepared by chemical activation of anthracite powders with sodium hydroxide, and were then compacted. Associating both high adsorptive capacities and high apparent densities finally allowed exceeding the target of 150 volumes of methane delivered per volume of storage vessel at 20ʿC and 3. 5 MPa. Formation of methane hydrates was also observed in micro mésoporous carbons, at 2ʿC and at pressures higher than 4 MPa
Casenave, Viviane. „Architecture et dynamique des migrations d'hydrocarbures dans une couverture sédimentaire à hydrates de gaz : implications sur le système pétrolier (bassin du Bas Congo)“. Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT143/document.
Der volle Inhalt der QuelleEvidence of fluid flow features and their mechanisms of migration through the sedimentary pile are a known phenomenon on continental margins. It has been widely studied over the past twenty years, notably due to the improved resolution of seismic data and the abundance of data in these areas due to oil and gas exploration.The Lower Congo basin, offshore West Africa, is a prolific petroleum province that has been extensively studied, and has been in operation for over 30 years. The area of interest is located above a producing oil field (the Moho license), in which hydrocarbons are trapped in turbidite channels. The work is primarily based on the analysis of geophysical data including 3D and 2D-THR seismic, multibeam bathymetry and corresponding backscatter, as well as background data (samples taken from ROV photos, geochemical analyses).The analysis of this important seismic dataset revealed abundant evidence of fluid migration in the Mio-Pliocene sedimentary pile. They mainly correspond to indications of vertically focused migration, including current fluid expulsion structures on the seafloor, and buried structures, interpreted as fossile and indicating former activity of the fluid expulsion system. The studied fluid migration features mainly consist of pockmarks (depressions) and carbonate cementations. These two types of indicators can build vertical stacks, over several hundred meters, highlighting the durability of the fluid escapes and suggesting the development of real pipes.A new type of pockmarks has been discovered, the spider structures, which are located above a turbiditic reservoir, and which result from a focused migration of thermogenic hydrocarbons. They are related to gas hydrates, in the context of a sloping BSR (Bottom Simulating Reflector), due to the presence of the hydrate wedge. A dynamic model of their functioning is proposed, showing that these structures develop upslope, due to the gas migration under the sloping BSR. A study of the BSR, in the particular context of the hydrates wedge, allows to propose a model of gas escapes, linked to the dissociation of the hydrates, during a sea level fall. This model presents a dissociation of gas hydrates of regional scale (associated with biogenic gas), localized at the gas hydrate wedge zone of the last lowstand. Finally, the network of fluid escape structures of the Mio-Pliocene interval was investigated in order to understand its architecture and the mechanisms of fluid migration in the study area. Hydrocarbons appear to migrate mainly along certain portions of faults and vertically crosscutting the sedimentary pile through pipes or chimneys. The base of the Pliocene, associated with a sea level fall, marks the formation of the first paleo-spiders, as well as a level containing numerous evidence of gas. A model of this network of fluid migrations is proposed, integrating the indicators of hydrocarbon migrations through the sedimentary pile, and the major event of the Pliocene base. This study seems to indicate that a the sea level fall constitute a trigger for the fluids migrations, in the basin.This work thus marks the starting point of a larger-scale investigation which consists in, on the one hand, searching for similar structures (spiders and bands of pockmarks) in other basins ; and, on the other hand, by comparing fluid flow events with the eustatic curve
Martinez, de Baños Maria Lourdes. „Mechanisms of formation and dissociation of cyclopentane hydrates“. Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3037/document.
Der volle Inhalt der QuelleThe mechanisms of formation and dissociation of cyclopentane (CP) hydrates, which form at ambient pressure and temperatures between 0°C and 7°C, have been observed in/on/near water drops immersed in CP at scales ranging from a few nanometers to the millimeter by a variety of techniques including macrophotography and optical microscopy under various modes: bright field, differential interference contrast (DIC), fluorescence and confocal reflectance. The substrates used are either hydrophobic or hydrophilic. In a first series of experiments, a simple millifluidic method is implemented. It allows to generate, store and monitor at the same time almost a hundred of regularly-spaced water droplets of equal volume (in the µl range) separated by the guest (CP) phase in a transparent fluorinated polymeric (PFA) (hydrophobic) tubing, each droplet behaving as an independent reactor for hydrate crystallization. Insights into the ‘memory effect’ are gained by measuring the statistics of hydrate nucleation events in these reactors when chilling below 7°C the water drops. The method also allows the visualization of single-drop events such as hydrate birth and growth, and the formation of a CP-in-water emulsion upon hydrate melting, especially when an additive such as an inhibitor is added to the water. In a second series of experiments, a single water droplet in CP, either sitting or hanging from a glass substrate, is observed by microscopy under various cooling and heating sequences. Hydrate crystallization (nucleation and growth) is observed to strongly depend on subcooling at the water drop/CP interface. Two novel phenomena are visualized in detail:(i) the propagation, from the contact line of the water drop, of a hydrate halo along the glass/CP interface. (ii) hydrate crystallization in a two-dimensional CP-in-water emulsion.The two types of tools developed in this thesis open new perspectives for elucidating the mechanisms of hydrate formation and dissociation in presence of additives (promoters and inhibitors) and in the presence of a mineral substrate. Applications include hydrates in sedimentary environments, flow assurance, gas separation, etc
Le, Thi Xiu. „Experimental study on the mechanical properties and the microstructure of methane hydrate-bearing sandy sediments“. Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC1039.
Der volle Inhalt der QuelleMethane hydrates (MHs), being solid ice-like compounds of methane gas and water, form naturally at high pressure and low temperature in marine or permafrost settings. They are being considered as an alternative energy resource (mainly methane hydrate-bearing sand, MHBS) but also a source of geo-hazards and climate change (MHs in both coarse and fine sediments). Knowledge of physical/mechanical properties of sediments containing MHs, depending considerably on hydrate morphologies and pore-habits, is of the importance to minimize the environmental impacts of future exploitations of methane gas from MHBS. Existing experimental works mainly focus on synthetic samples due to challenges to get cored intact methane hydrate-bearing sediment samples. Various methods have been proposed for MH formation in sandy sediments to mimic natural MHBS, but without much success. The main interests of this thesis are to investigate morphologies and pore-habits of MHs formed in synthetic MHBS at various scales and to study the effects of MHs (MH morphology and MH saturation) on the mechanical properties of MHBS.Two MH formation methods (modified from two methods existing in the literature) have been first proposed to create MHs in sandy sediments at different pore-habits. At the macroscopic scale, MH pore-habits have been predicted via comparisons between sonic wave velocities, measured and that calculated based on rock physic models. The effects of MHs formed following the two proposed methods (at different hydrate saturations) on the mechanical properties of MHBS were investigated by triaxial tests. Furthermore, Magnetic Resonance Imaging (MRI) has been used to investigate the kinetics of MH formation, MH distribution along with sample height and also MH dissociation following the depressurization method which has been considered as the most economical method for MH production from MHBS. A temperature cycle in undrained conditions was supposed to not only complete MH redistribution in pore space after the water saturation of the sample at high hydrate saturation but also make MHs distributed more homogeneously in the sample even at low hydrate saturation. Furthermore, the mechanical properties of sediments (e.g. stiffness, strength) were found higher at higher MH saturation.At the grain scale, the MH morphologies and pore habits in sandy sediments were observed by X-Ray Computed Tomography (XRCT, at Navier laboratory, Ecole des Ponts ParisTech) and Synchrotron XRCT (SXRCT, at Psiche beamline of Synchrotron SOLEIL). It has been really challenging due to not only the need of special experimental setups (needing both high pressure and low temperature controls) but also poor XRCT, SXRCT image contrast between methane hydrate and water. Specific experimental setups and scan conditions were then developed for pore-scale investigations of MH growth and MH morphologies in sandy sediments by using XRCT, SXRCT. Besides, a new method has been developed for accurate determination of volumetric fractions of a three-phase media from XRCT images. Observations (at better spatial and temporal resolution) via Optical Microscopy (in cooperation with the University of Pau) were finally used to confirm diverse MH morphologies in sandy sediments. Comparisons between observed MH morphologies, pore habits, and existing idealized models have been discussed. Methane hydrate formation in sandy sediments was supposed to be an unstable and complex process. Different types of MH morphologies and pore habits could exist in the sample. It seems vital that numerical studies on the mechanical behavior of gas hydrates in sediments, based on four idealized hydrate pore-habits, should take into account realistic hydrate morphologies and pore habits.Keywords:Methane hydrates, sandy sediments, formation, dissociation, morphologies, pore-habits, mechanical properties, XRCT, SXRCT, optical microscopy, triaxial tests, rock physic model
Thiéry, Régis. „Les systèmes eau-gaz-sels : modélisation des équilibres de phases et application aux fluides géologiques“. Vandoeuvre-les-Nancy, INPL, 1996. http://docnum.univ-lorraine.fr/public/INPL_T_1996_THIERY_R.pdf.
Der volle Inhalt der QuelleFreire, Brântuas Pedro. „Captage du dioxyde de carbone par des semiclathrate hydrates : Modélisation, expérimentation et dimensionnement d’une unité pilote“. Thesis, Saint-Etienne, EMSE, 2013. http://www.theses.fr/2013EMSE0691/document.
Der volle Inhalt der QuelleGas hydrates are a non conventional way of trapping and storing gas molecules trough the crystallization of water under the high pressure and low temperature conditions. Quaternary ammonium salts form hydrates at atmospheric pressure and can also form mixed hydrates in the presence of gas. It’s important to know their thermodynamic properties in order to evaluate their potential applications: one of these applications is the capture of carbon dioxide from flue gas. The semiclathrates studied were made from peralkylamonium salts (TBAB, TBACl, TBAF) and tetrabutyl phosphonium bromide (TBPB) plus several gases: CO2, N2, and CH4. The formation pressure was greatly reduced with regards to the respective gas hydrates. An eNRTL model for determining the activity coefficients of hydrate forming systems with salts has been used. Single and double salts systems were analyzed in the presence of CH4 and the data obtained is in a good agreement with the literature. The TBAB and CH4 semiclathrates system was also investigated with the results being different of those of the literature probably due to a difference on the structure of the semiclathrate. However, the results are promising, and the model gives a good predictionBased on the experimental results, a pilot plant scale process was designed. This new process consists in forming mixed hydrates of TBAB and CO2 in a bubble column. The hydrates are then removed from the column and after expansion, the mixed hydrates transform into TBAB hydrates releasing CO2, which can be returned to the bubble column
Jatiault, Romain. „Les émanations naturelles d'hydrocarbures lourds depuis les sédiments vers l'hydro-atmosphère : approche intégrée multiéchelle dans le bassin profond du bas-congo“. Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0047/document.
Der volle Inhalt der QuelleThe Lower Congo Basin is a passive margin, affected by strong salt tectonics. Natural escapes of heavy hydrocarbons observed in the area have major impacts on the society, ecology, biology, and the economy. The aim of this work is to understand the mechanisms of these systems, from the mobilisation in the sediments towards the seafloor outlets and subsequently towards the sea surface. This study combines data analysis from spatial imagery, oceanography, geochemistry and marine geophysics in order to get a multi-scale integrated vision of the natural seepage situation in the Lower Congo Basin. The analysis of spatial imagery data shows that in the study area, the hundred active seeps sites expel a hydrocarbons volume of 4400 m3 per year, following an intermittent mechanism with miscellaneous frequencies from one site to another. We connected visible hydrocarbon slicks at the sea surface with seabed structures by integrating current measurements across the water column. Seafloor structures correspond to clustered pockmarks of high seismic amplitude located at the rim of salt diapirs and to clusters of mounds composed of highly degraded oil outwards. In sediments, geophysical anomalies form vertical chimneys, delimited by the seismic reflector associated with the base of gas hydrates stability downwards. The spatial correspondence of geophysical criteria enabled to inventory the potentially active sites on the geophysical data. Only 40% of these sites are associated with recurring oil slicks at the sea surface
Pham, Trung-Kien. „Etude expérimentale et modélisation de la cristallisation d’hydrates de méthane en écoulement a partir d’une dispersion eau-huile a fort pourcentage d’eau“. Thesis, Lyon, 2018. https://tel.archives-ouvertes.fr/tel-02869624.
Der volle Inhalt der QuelleProduction of crude oil with natural gas and water at low temperature and high pressure favors conditions for gas hydrate formation which might cause many troubles in flow assurance, up to blockage of pipelines. To prevent plugging, varieties of methods are applied to flowlines by addition of thermodynamic inhibitors (THIs), kinetic hydrate inhibitors (KHIs) and anti-agglomerants (AAs). Recently, AAs are more widely used due to not only their high performance at severe conditions but also the reduction in costs of operation at low dosage (AA-LDHIs). Mostly, previous studies on gas hydrate formation and transport have focused on low water cuts and without anti-agglomerants. On the contrary, at high water cuts, the gas hydrate formation and transport in the presence of AA-LDHI and/or salt in pipelines are not widely understood. The principal objective of this study is a better understanding on hydrate formation and plugging by testing the role of commercial additives to avoid plugging. In details, this work deals with hydrate kinetics of crystallization and agglomeration together with hydrate slurry transport and deposition under flowing conditions (especially at high water cuts). Effects of various parameters were studied, including the amount of commercial anti-agglomerants (AA-LDHIs), water volume fraction, and water salinity in a mixture of Kerdane® oil and water. The experiments were performed in the “Archimède” 80 bar - pilot scale flowloop which reproduces the conditions in oil and gas transport in subsea pipelines. The experimental apparatus is equipped with a FBRM (Focused Beam Reflectance Measurement) and a PVM (Particle Video Microscope) probe and temperature, pressure drop, flowrate and density sensors. The flow was induced through Moineau pump and/or a “gas-lift” system. The results revealed that with gas-lift protocol; hydrates formed on the surface of gas bubbles and water droplets and they were transported in oil and water continuous phases. Generally, the hydrates tend to deposit at high water cut and agglomerate at low water cut. Mechanisms of hydrate formation and transport with and without AA-LDHI in bubble conditions were proposed. With Moineau pump protocol; effects of hydrate formation
Jin, Dongliang. „Thermodynamique et cinétique de la formation de l'hydrate de méthane confiné dans un milieu nanoporeux : théorie et simulation moléculaire“. Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY076/document.
Der volle Inhalt der QuelleMethane hydrate is a non-stoichiometric crystal in which water molecules form hydrogen-bonded cages that entrap methane molecules. Abundant methane hydrate resources can be found on Earth, especially trapped in mineral porous rocks (e.g., clay, permafrost, seafloor, etc.). For this reason, understanding the thermodynamics and formation kinetics of methane hydrate confined in porous media is receiving a great deal of attention. In this thesis, we combine computer modeling and theoretical approaches to determine the thermodynamics and formation kinetics of methane hydrate confined in porous media. First, the state-of-the-art on the thermodynamics and formation kinetics of methane hydrate is presented. Second, different molecular simulation strategies, including free energy calculations using the Einstein molecule approach, the direct coexistence method, and the hyperparallel tempering technique, are used to assess the phase stability of bulk methane hydrate at various temperatures and pressures. Third, among these strategies, the direct coexistence method is chosen to determine the shift in melting point upon confinement in pores, $Delta T_m = T_{m}^{pore} - T_{m}^{bulk}$ where $T_m^{pore}$ and $T_m^{bulk}$ are the melting temperatures of bulk and confined methane hydrate. We found that confinement decreases the melting temperature, $T_m^{pore}
Izquierdo, Ruiz Fernando. „Clatratos Hidratos de Gas en Condiciones Extremas“. Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS187/document.
Der volle Inhalt der QuelleThis document contains a scientific report resulting from more than four years of theoretical and experimental research on a particular kind of physicochemical systems called gas clathrate hydrates. These systems are inclusion compounds constituted by a three dimensional water framework hosting gas molecules with low dipolar moments in its cavities. Gas clathrate hydrates are very important in a great variety of scientific fields related to life sciences or planetology, and they are also considered as a main natural resource for the energy industry. Usually, gas clathrate hydrates need high pressure and low temperature to be thermodynamically stable. Depending on these conditions, differentphases have been detected being the most common ones the cubic structuressI and sII, the hexagonal sH, and the orthorhombic Filled Ice Structure(FIS). Our study has substantially advanced in the knowledge of the behaviorof methane and carbon dioxide clathrate hydrates under different pressure andtemperature conditions. In particular, we have contributed to: (i) the determination and understanding of stability thermodynamic regions, (ii) the characterizationof a controversial high-pressure structure, and (iii) setting up a new experimental equipment for Raman measurements in a pressure range up to 1 GPa [...]
Este documento contiene el informe científico resultante después de más de cuatro años de investigación teórica y experimental sobre un tipo particular de sistemas físico-químicos llamados clatratos hidratos de gas. Estos sistemas son compuestos de inclusión constituidos por un armazón tridimensional de agua que aloja en sus cavidades moléculas de gas con momentos dipolares bajos.Los clatratos hidratos de gas son muy importantes en una gran variedad de campos científicos relacionados con las ciencias de la vida o la planetología, y también se consideran como uno de los principales recursos naturales para la industria energética. Por lo general, los clatratos hidratos de gas necesitan alta presión y baja temperatura para ser termodinámicamente estables.Dependiendo de estas condiciones, se han detectado diferentes fases siendo las más comunes las estructuras cúbicas sI y sII, hexagonal sH y la estructura ortorrómbica de hielo relleno (FIS). Nuestro estudio ha avanzado sustancialmente en el conocimiento del comportamiento de los clatratos hidratos de metano y dióxido de carbono en diferentes condiciones de presión y temperatura, proporcionando (i) regiones termodinámicas de estabilidad, (ii) la caracterización de una estructura de alta presión controvertida y (iii) un nuevo equipo experimental para mediciones Raman en un rango de presión de hasta 1 GPa [...]
Atig, Dyhia. „Propriétés physiques et mécaniques de l’hydrate de méthane à l’échelle du pore“. Thesis, Pau, 2019. http://www.theses.fr/2019PAUU3021.
Der volle Inhalt der QuelleGas hydrates are ice-like crystals stable at high pressure and low temperature. They are ubiquitous on earth, notably at the edges of continental shelves, where they contribute to the mechanical stability of marine sediments, by hydrate cohesion and hydrate adhesion to mineral particles. However, the mechanical behavior of gas hydrates at pore scale has been hardly or not at all studied. The purpose of this thesis is to study the stability conditions and the tensile mechanical properties of methane hydrate at pore scale in a representative pore habit of gas hydrate in a sedimentary medium.Here, using optical microscopy, first the formation, growth and dissociation conditions of methane hydrate are investigated across a water/CH4 interface in glass micro-capillaries used both as a pore model and as an optical cell resisting high pressure and low temperature. Then by developing a contactless and an in situ method, "thermally induced depressing", tensile mechanical properties of polycrystalline methane hydrate shell are determined. At low enough temperature, the hydrate nucleates as a polycrystalline "crust" over the water/CH4 interface. From this crust, the hydrate continues growing on both sides of the interface: in the water as "needle like crystals", in the gas as "hair like crystals", and finally between the gas and the substrate as a polycrystalline film, the "halo". The halo advances slowly on the substrate, riding over a water film, and comes to rest and adheres to the substrate. From then on, the "shell" (crust and halo) isolates the water from the gas. Tensile tests are carried out by generating a depression in the water compartment by increasing temperature at constant methane pressure.Tensile elastic properties of the shell (elastic modulus and the tensile strength) are determined as a function of the grain size, controlled here by two parameters, supercooling compared to the equilibrium temperature and the annealing time. We find elastoplastic behavior, with mixed ductile and brittle characteristics. Our data on tensile strength contribute to fit the gap of five orders of magnitude of grain size, and three orders of magnitude of tensile strength (between molecular simulations at nanometre scale and current experiment at millimetre to centimetre scale). The effect of grain size on the tensile strength of methane hydrate could be a factor contributing to the destabilization of continental slopes
Galfré, Aurélie. „Captage du dioxyde de carbone par cristallisation de clathrate hydrate en présence de cyclopentane : Etude thermodynamique et cinétique“. Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2014. http://tel.archives-ouvertes.fr/tel-00993771.
Der volle Inhalt der QuelleDouzet, Jérôme. „Conception, construction, experimentation et modelisation d’un banc d’essais grandeur nature de climatisation utilisant un fluide frigoporteur diphasique a base d’hydrates de tbab“. Thesis, Saint-Etienne, EMSE, 2011. http://www.theses.fr/2011EMSE0616/document.
Der volle Inhalt der QuelleFor some years, new industrial processes have been developed and marketed in the refrigeration and air conditioning fields. Among systems which begin to have good business opportunities some are using two-phase secondary refrigerants solid / liquid. This kind of technology offers the advantages of reducing the use of classical refrigerants which are regulated and can smooth the production of cold over 24 hours with its ability to store the slurry. At the European level, thanks to the efforts of several manufacturers, the refrigeration field is developing fast with respect to the use of ice slurries. Moreover the industrial or district air conditioning field is a major energetic issue in terms of the immediate energy it requires as well as in terms of "peaks" generated during certain periods of the day.In this field, especially in Japan, the use of “PCM” (Phase Change Material) is additionally developing. In this technological segment, the PCM used are hydrate slurries. This solution has the advantage of crystallizing at positive temperatures which is more suited for the air conditioning than ice slurries.This research work deals with the adaption of a refrigeration technology available on the European market to the field of air conditioning. The fluid used is an aqueous solution of TBAB (Tetra-Butylammonium Bromide) with a crystallization temperature at atmospheric pressure which can be adjusted to a temperature between 6 and 12°C. The experimental device designed and installed is a real size prototype able to cool 4 rooms. Both the industrial demonstrator as well as instrumented test bench allowed us to carry out practice sessions which demonstrated the feasibility of the process. It also allowed us to design improvements and new developments. In parallel to the construction and the experiments, additional measurements concerning some thermo-physical characteristics of TBAB hydrate slurries were conducted in specialised laboratory. Finally, a modelling tool was also developed in order to relate our experiments with theoretical thermo-physical phenomena. This numerical model is intended to be a predicative tool for the design of new installations and for the development of the prototype
Youssef, Ziad. „Étude thermodynamique de la formation d'hydrates en absence d'eau liquide : mesures et modélisation“. Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00694018.
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