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Articoli di riviste sul tema "Hydrates de gaz naturel – Additifs":
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Li, Bo, You-Yun Lu e Yuan-Le Li. "A Review of Natural Gas Hydrate Formation with Amino Acids". Journal of Marine Science and Engineering 10, n. 8 (17 agosto 2022): 1134. http://dx.doi.org/10.3390/jmse10081134.
Abstract (sommario):
Natural gas is a kind of low-carbon energy source with abundant reserves globally and high calorific value. It is cleaner and more efficient than oil and coal. Enlarging the utilization of natural gas is also one of the important ways to reduce carbon emissions in the world. Solidified natural gas technology (SNG) stores natural gas in solid hydrates, which is a prospective, efficient, safe and environmental-friendly strategy of natural gas storage and transport. However, the slow growth rate and randomness of nucleation during natural gas hydrate formation in pure water hinder the industrial application of this technology. As a kind of new and potential additives, biodegradable amino acids can be adopted as favorable kinetic promoters for natural gas hydrate synthesis. Compared with other frequently used chemical additives, amino acids are usually more friendly to the environment, and are capable of avoiding foam formation during complete decomposition of gas hydrates. In this paper, we have reviewed the research progress of gas hydrate generation under the promotion of amino acids. The formation systems in which amino acids can enhance the growth speed of gas hydrates are summarized, and the impact of the concentration in different systems and the side chains of amino acids on hydrate growth have been illustrated. The thermodynamic and kinetic behaviors as well as the morphology properties of hydrate formation with amino acids are summarized, and the promotion mechanism is also analyzed for better selection of this kind of potential additives in the future.
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Liu, Huaxin, Meijun Li, Hongfei Lai, Ying Fu, Zenggui Kuang e Yunxin Fang. "Controlling Factors of Vertical Geochemical Variations in Hydrate-Rich Sediments at the Site GMGS5-W08 in the Qiongdongnan Basin, Northern South China Sea". Energies 17, n. 2 (14 gennaio 2024): 412. http://dx.doi.org/10.3390/en17020412.
Abstract (sommario):
Large amounts of natural gas hydrates have been discovered in the Qiongdongnan Basin (QDNB), South China Sea. The chemical and stable carbon isotopic composition shows that the hydrate-bound gas was a mixture of thermogenic and microbial gases. It is estimated that microbial gas accounts for 40.96% to 60.58%, showing a trend of decrease with the increase in burial depth. A significant amount of gas hydrates is thought to be stored in the mass transport deposits (MTDs), exhibiting vertical superposition characteristics. The stable carbon isotopic values of methane (δ13C1) in the MTD1, located near the seabed, are less than −55‰, while those of the methane below the bottom boundary of MTD3 are all higher than −55‰. The pure structure I (sI) and structure II (sII) gas hydrates were discovered at the depths of 8 mbsf and 145.65 mbsf, respectively, with mixed sI and sII gas hydrates occurring in the depth range 58–144 mbsf. In addition, a series of indigenous organic matters and allochthonous hydrocarbons were extracted from the hydrate-bearing sediments, which were characterized by the origin of immature terrigenous organic matter and low-moderate mature marine algal/bacterial materials, respectively. More allochthonous (migrated) hydrocarbons were also discovered in the sediments below the bottom boundary of MTD3. The gas hydrated is “wet gas” characterized by a low C1/(C2 + C3) ratio, from 2.55 to 43.33, which was mainly derived from a deeply buried source kitchen at a mature stage. There is change in the heterogeneity between the compositions of gas and biomarkers at the site GMGS5-W08 along the depth and there is generally a higher proportion of thermogenic hydrocarbons at the bottom boundary of each MTDs, which indicates a varying contribution of deeply buried thermogenic hydrocarbons. Our results indicate that the MTDs played a blocking role in regulating the vertical transportation of hydrate-related gases and affect the distribution of gas hydrate accumulation in the QDNB.
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Graue, Arne, B. Kvamme, Bernie Baldwin, Jim Stevens, James J. Howard, Eirik Aspenes, Geir Ersland, Jarle Husebo e D. Zornes. "MRI Visualization of Spontaneous Methane Production From Hydrates in Sandstone Core Plugs When Exposed to CO2". SPE Journal 13, n. 02 (1 giugno 2008): 146–52. http://dx.doi.org/10.2118/118851-pa.
Abstract (sommario):
Summary Magnetic resonance imaging (MRI) of core samples in laboratory experiments showed that CO2 storage in gas hydrates formed in porous rock resulted in the spontaneous production of methane with no associated water production. The exposure of methane hydrate in the pores to liquid CO2 resulted in methane production from the hydrate that suggested the exchange of methane molecules with CO2 molecules within the hydrate without the addition or subtraction of significant amounts of heat. Thermodynamic simulations based on Phase Field Theory were in agreement with these results and predicted similar methane production rates that were observed in several experiments. MRI-based 3D visualizations of the formation of hydrates in the porous rock and the methane production improved the interpretation of the experiments. The sequestration of an important greenhouse gas while simultaneously producing the freed natural gas offers access to the significant amounts of energy bound in natural gas hydrates and also offers an attractive potential for CO2 storage. The potential danger associated with catastrophic dissociation of hydrate structures in nature and the corresponding collapse of geological formations is reduced because of the increased thermodynamic stability of the CO2 hydrate relative to the natural gas hydrate. Introduction The replacement of methane in natural gas hydrates with CO2 presents an attractive scenario of providing a source of abundant natural gas while establishing a thermodynamically more stable hydrate accumulation. Natural gas hydrates represent an enormous potential energy source as the total energy corresponding to natural gas entrapped in hydrate reservoirs is estimated to be more than twice the energy of all known energy sources of coal, oil, and gas (Sloan 2003). Thermodynamic stability of the hydrate is sensitive to local temperature and pressure, but all components in the hydrate have to be in equilibrium with the surroundings if the hydrate is to be thermodynamically stable. Natural gas hydrate accumulations are therefore rarely in a state of complete stability in a strict thermodynamic sense. Typically, the hydrate associated with fine-grain sediments is trapped between low-permeability layers that keep the system in a state of very slow dynamics. One concern of hydrate dissociation, especially near the surface of either submarine or permafrost-associated deposits, is the potential for the release of methane to the water column or atmosphere. Methane represents an environmental concern because it is a more aggressive (~25 times) greenhouse gas than CO2. A more serious concern is related to the stability of these hydrate formations and its impact on the surrounding sediments. Changes in local conditions of temperature, pressure, or surrounding fluids can change the dynamics of the system and lead to catastrophic dissociation of the hydrates and consequent sediment instability. The Storegga mudslide in offshore Norway was created by several catastrophic hydrate dissociations. The largest of these was estimated to have occurred 7,000 years ago and was believed to have created a massive tsunami (Dawson et al. 1988). The replacement of natural gas hydrate with CO2 hydrate has the potential to increase the stability of hydrate-saturated sediments under near-surface conditions. Hydrocarbon exploitation in hydrate-bearing regions has the additional challenge to drilling operations of controlling heat production from drilling and its potential risk of local hydrate dissociation (Yakushev and Collett 1992). The molar volume of hydrate is 25-30% greater than the volume of liquid water under the same temperature-pressure conditions. Any production scenario for natural gas hydrate that involves significant dissociation of the hydrate (e.g., pressure depletion) has to account for the release of significant amounts of water that in turn affects the local mechanical stress on the reservoir formation. In the worst case, this would lead to local collapse of the surrounding formation. Natural gas production by CO2 exchange and sequestration benefits from the observation that there is little or no associated liquid water production during this process. Production of gas by hydrate dissociation can produce large volumes of associated water, and can create a significant environmental problem that would severely limit the economic potential. The conversion from methane hydrate to a CO2 hydrate is thermodynamically favorable in terms of free energy differences, and the phase transition is coupled to corresponding processes of mass and heat transport. The essential question is then if it is possible to actually convert methane hydrate as found in sediments to CO2 hydrate. Experiments that formed natural gas hydrates in porous sandstone core plugs used MRI to monitor the dynamics of hydrate formation and reformation. The paper emphasizes the experimental procedures developed to form the initial natural gas hydrates in sandstone pores and the subsequent exchange with CO2 while monitoring the dynamic process with 3D imaging on a sub millimetre scale. The in-situ imaging illustrates the production of methane from methane hydrate when exposed to liquid CO2 without any external heating.
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Khan, Muhammad Saad, Bhajan Lal, Hani Abulkhair, Iqbal Ahmed, Azmi Mohd Shariff, Eydhah Almatrafi, Abdulmohsen Alsaiari e Omar Bamaga. "Formation Kinetics Evaluation for Designing Sustainable Carbon Dioxide-Based Hydrate Desalination via Tryptophan as a Biodegradable Hydrate Promotor". Sustainability 15, n. 1 (1 gennaio 2023): 788. http://dx.doi.org/10.3390/su15010788.
Abstract (sommario):
Desalination using hydrates is a developing field, and initial research promises a commercially feasible approach. The current study proposes the natural amino acid, namely tryptophan, as a biodegradable gas hydrate promotor for desalination applications to speed up the hydrate formation process. Its kinetic behavior and separation capabilities with CO2 hydrates were investigated. The studies were carried out with varying concentrations (0.5, 1, and 2 wt.%) of tryptophan at different experimental temperatures (274.15, 275.15, 276.15, and 277.15 K) at 3.5 and 4.0 MPa pressure and 1 wt.% brine concentration. The induction time, initial formation rates, gas uptake, and water recovery are characterized and reported in this work. Overall finding demonstrated that tryptophan efficiently acted as a kinetic hydrate promotor (KHP), and increased tryptophan quantities further supported the hydrate formation for almost all the studied conditions. The formation kinetics also demonstrated that it shortens the hydrate induction time by 50.61% and increases the 144.5% initial formation rate of CO2 hydrates for 1 wt.% addition of tryptophan at 274 K temperature and 4.0 MPa pressure condition. The study also discovered that at similar experimental conditions, 1 wt.% tryptophan addition improved gas uptake by 124% and water recovery moles by 121%. Furthermore, the increased concentrations of tryptophan (0.5–2 wt.%) further enhance the formation kinetics of CO2 hydrates due to the hydrophobic nature of tryptophan. Findings also revealed a meaningful link between hydrate formation and operating pressure observed for the exact temperature settings. High pressures facilitate the hydrate formation by reduced induction times with relatively higher formation rates, highlighting the subcooling effect on hydrate formation conditions. Overall, it can be concluded that using tryptophan as a biodegradable kinetic promotor considerably enhances the hydrate-based desalination process, making it more sustainable and cost-effective.
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Jarrahian, Azad, e Ehsan Heidaryan. "Natural gas hydrate promotion capabilities of toluene sulfonic acid isomers". Polish Journal of Chemical Technology 16, n. 1 (1 marzo 2014): 97–102. http://dx.doi.org/10.2478/pjct-2014-0017.
Abstract (sommario):
Abstract The purpose of this study was to investigate the natural gas hydrate promotion capabilities of the hydrotrope Toluene Sulfonic Acid (TSA) isomers as an additive. The capabilities of TSA isomers were measured with different concentrations. The optimum additive concentration for hydrate formation was determined for the given pressure, temperature, mixing condition, and cooling time. The natural gas hydrate promotability of para-TSA was found to be 20% and 35% more than meta-TSA and ortho-TSA respectively at the optimum concentration. Beyond the optimum TSA concentration, the hydrate formation declined as the ice formation reduced the overall gas-to-water volume ratio in the hydrates
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Chuvilin, Evgeny, e Dinara Davletshina. "Formation and Accumulation of Pore Methane Hydrates in Permafrost: Experimental Modeling". Geosciences 8, n. 12 (10 dicembre 2018): 467. http://dx.doi.org/10.3390/geosciences8120467.
Abstract (sommario):
Favorable thermobaric conditions of hydrate formation and the significant accumulation of methane, ice, and actual data on the presence of gas hydrates in permafrost suggest the possibility of their formation in the pore space of frozen soils at negative temperatures. In addition, today there are several geological models that involve the formation of gas hydrate accumulations in permafrost. To confirm the literature data, the formation of gas hydrates in permafrost saturated with methane has been studied experimentally using natural artificially frozen in the laboratory sand and silt samples, on a specially designed system at temperatures from 0 to −8 °C. The experimental results confirm that pore methane hydrates can form in gas-bearing frozen soils. The kinetics of gas hydrate accumulation in frozen soils was investigated in terms of dependence on the temperature, excess pressure, initial ice content, salinity, and type of soil. The process of hydrate formation in soil samples in time with falling temperature from +2 °C to −8 °C slows down. The fraction of pore ice converted to hydrate increased as the gas pressure exceeded the equilibrium. The optimal ice saturation values (45−65%) at which hydrate accumulation in the porous media is highest were found. The hydrate accumulation is slower in finer-grained sediments and saline soils. The several geological models are presented to substantiate the processes of natural hydrate formation in permafrost at negative temperatures.
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Luan, Hengjie, Mingkang Liu, Qinglin Shan, Yujing Jiang, Peng Yan e Xiaoyu Du. "Experimental Study on the Effect of Mixed Thermodynamic Inhibitors with Different Concentrations on Natural Gas Hydrate Synthesis". Energies 17, n. 9 (26 aprile 2024): 2078. http://dx.doi.org/10.3390/en17092078.
Abstract (sommario):
Natural gas hydrate (NGH) is a potential future energy resource. More than 90% of NGH resources exist in the pore medium of seafloor sediments. During the development of deep-sea oil and gas fields, wellbore pipelines are often clogged due to the synthesis of gas hydrates, and the addition of thermodynamic inhibitors is a common solution to prevent hydrate synthesis. In this paper, the effects of two single inhibitors, sodium chloride and ethylene glycol, as well as hybrid inhibitors combining these two inhibitors on the synthesis of methane hydrates were investigated using the self-developed one-dimensional gas hydrate exploitation simulation test apparatus. The effects of single and hybrid inhibitors were investigated in terms of the hydrate synthesis volume and gas–water two-phase conversion rate. The results show that the hybrid inhibitor has a better inhibitory effect on hydrate synthesis with the same initial synthesis driving force. When the concentration of inhibitors is low, salt inhibitors can have a better inhibitory effect than alcohol inhibitors. However, in the mixed inhibitor experiment, increasing the proportion of ethylene glycol in the mixed inhibitor can more effectively inhibit the synthesis of hydrates than increasing the proportion of sodium chloride in the mixed inhibitor.
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Dmytrenko, Victoriia, Oleksandr Lukin e Vasyl Savyk. "The influence of the gas hydrates morphology on the rate of dissociation and the manifestation of self-preservation in non-equilibrium conditions". Technology audit and production reserves 3, n. 1(65) (30 giugno 2022): 39–43. http://dx.doi.org/10.15587/2706-5448.2022.261716.
Abstract (sommario):
The object for the research was samples of artificially formed gas hydrate of different morphology. Gas hydrates are clathrate compounds of water molecules and hydrate-forming gases. They create significant problems for the oil and gas industry. At the same time, they contain enormous natural gas resources. The study of gas hydrates requires the production of quality samples in laboratory conditions and the availability of appropriate laboratory equipment. However, it is customary to use averaged physical indicators when performing calculations and in works on modeling gas-hydrate processes. At the same time, their morphological differences are not taken into account. Therefore, there is a risk of obtaining distorted research results. Based on this, the paper presents an analysis of the morphological differences of artificially formed gas-hydrate structures depending on the method of their formation. An assessment of the influence of the method of gas hydrate formation and the morphology of artificially formed gas hydrate samples on its stability is also given. In addition, recommendations are provided for choosing a method of forming samples of gas-hydrate structures that simulate natural samples. Gas hydrate samples for research were obtained at a laboratory facility by changing the method of mixing the contents of the reactor. The basis of the research methodology was the analysis of enlarged images of gas hydrate samples. The morphology of the gas hydrate samples was studied through the transparent viewing windows of the reactor. For obtain high-quality images, an optical system with a light source inside the reactor was used. The stability of the gas hydrate samples was investigated with gradual pressure release in the reactor. The difficulty of obtaining adequate samples of artificial gas hydrates for modeling the properties of natural analogues is shown. It is shown that morphological differences in the macro- or microstructure of artificially formed gas hydrate samples can affect the results of research. It was concluded that the results of experimental studies with samples of artificially obtained gas hydrate cannot be considered adequate for real conditions without appropriate corrections.
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Portnyagin, A. S., I. K. Ivanova, L. P. Kalacheva e V. V. Portnyagina. "Studying the Formation of Natural Gas Hydrates in a Porous Medium from a Polymer – Solution – Oil Mixture". Chemistry and Technology of Fuels and Oils 638, n. 4 (2023): 24–28. http://dx.doi.org/10.32935/0023-1169-2023-638-4-24-28.
Abstract (sommario):
The article presents the results of studies of equilibrium conditions and kinetic characteristics of the processes of formation of natural gas hydrate in systems of porous medium - water - polymer - calcium chloride - oil under static conditions. It has been established that, formation of methane and natural gas hydrates mixture occurs in the systems under study. The presence of oil in the reaction system does not affect the equilibrium conditions of the gas hydrates formation within the error but reduces the hydrate formation rateand water-to hydrate convertion. The presence of the CaCl2 salt in the system shifts the equilibrium conditions of hydrate formationto the region of low temperatures. The effect of calcium chloride on the kinetics in a system without polymers has an extreme dependenceand makes it possible to double the gas uptake rate at 50 g/L. The addition of polymers (polyacrylamide, sodium carboxymethyl cellulose, or polyethylene glycol) to the system suppresses the salt effect. The data obtained can be useful in the developmentof reagents for polymer flooding of an oil reservoir during oil production under conditions of gas hydrate stability.
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Goshovskyi, S. V., e Oleksii Zurian. "METHODS AND TECHNOLOGIES OF METHANE GAS EXTRACTION FROM AQUA GAS HYDRATE FORMATIONS". Мінеральні ресурси України, n. 4 (28 dicembre 2018): 26–31. http://dx.doi.org/10.31996/mru.2018.4.26-31.
Abstract (sommario):
In the bowels of the Earth and in the oceans of the World Ocean, there are practically unlimited resources of natural gas in the solid hydrate state, available to most countries of the world community. The development of gas hydrate deposits is based on the process of dissociation (separation), in which the gas hydrates break down into gas and water. In these technologies, three methods for the development of gas hydrate deposits are proposed: pressure reduction, heating and inhibitor input. Based on the systematized data, the above methods are suggested to be attributed to traditional methods, as the most studied and classical ones. It is proposed to identify a number of methods that imply the same results, but use other physical approaches and designate them as unconventional. 1. Decomposition of methane hydrates by nanoparticles. In this method, the use of nanoparticles commensurate with the gas hydrate cell (supplied as part of a hydrodynamic jet) is proposed for efficient and safe destruction of the gas hydrate. The application of nanotechnology provides effective and consistent study of the entire surface of the aquatic deposit of gas hydrates, with the necessary rate of their destruction and the production of planned volumes of methane. 2. Decomposition of methane hydrates by microorganisms (bacteria). In this process, in the process of the life of the bacteria, a gas must be released, replacing in the clathrate structure a molecule of methane per molecule of the given gas. In addition, the process must be controlled by the use of external factors that provide nutrition to the bacteria and at the same time, light, chemicals, electromagnetic radiation, etc. can be stopped at any time, which is absent in the natural conditions of formation of the gas hydrate.
Tesi sul tema "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.
Abstract (sommario):
Dans le cadre de la production pétrolière, la formation d’hydrates de gaz peut conduire à la formation de dépôts, au bouchage des lignes et à l’interruption de la production du pétrole et/ou du gaz. La formation d’hydrate peut donc avoir un impact économique fort. Pour assurer la production sans risque d’arrêt de production, différentes stratégies sont adoptées. Une stratégie courante implique la production hors zone hydrates par injection d’additifs thermodynamiques (THIs) par exemple. Cependant, le déplacement des conditions de stabilité des hydrates par les THIs nécessitent l’injection de doses massives d’additif avec un coût environnemental et économique élevés. Une autre stratégie de production, en zone hydrate, consiste à injecter des additifs dits à faible doses (LDHI) : les inhibiteurs cinétiques (KHIs) ou les anti-agglomérants (AAs). Pour les champs pétroliers sous-marins profonds (deep offshore), seule l’injection d’additifs anti-agglomérants (AAs) est pertinente. Ces additifs ne bloquent pas la formation des hydrates mais évitent leur agglomération et dispersent les cristaux formés dans les fluides de production. Le développement des AAs et la validation de leurs applications sur des champs de production nécessitent une investigation approfondie de leurs impacts sur les systèmes réels de production (dispersion des cristaux dans les conduites, la taille des cristaux dans la phase continue, la transportabilité des suspensions, etc…).êPour apporter une meilleure compréhension de l’impact des additifs anti-agglomérants commerciaux (AAs) sur la formation d’hydrates une approche pluridisciplinaire et multi-échelles a été adoptée. La formation d’hydrates de gaz naturel a tout d’abord été réalisée au laboratoire en reproduisant les conditions de production pétrolière avec des systèmes industriels dans des conditions opérationnelles avec trois AA différents. À l’échelle macroscopique, les suspensions de cristaux réalisées sous agitation dans les réacteurs mettent en évidence des effets dépendants de l’AA utilisé. Ils impactent différemment la cinétique de formation des hydrates, le taux et la vitesse de croissance des cristaux ainsi que leur état de dispersion. Sans agitation, ces additifs AAs affectent la morphologie et contrôlent la croissance des cristaux et la phase dans laquelle ils vont croître. Ensuite, une cellule de transfert d’hydrates a été conçue pour prélever des échantillons de suspensions d’hydrates formés dans les réacteurs dans des conditions proches de la réalité industrielle (avec agitation, pression élevée, faible température). Les suspensions d’hydrates transférées ont ensuite été analysées par microtomographie à rayons X à l’aide d’une méthode développée au cours de ce travail. À l’échelle microscopique, l’état de dispersion des grains d’hydrates a été évalué pour l’ensemble des échantillons transférés et des informations ont été obtenues sur la taille des grains d’hydrates dispersés, leur forme et leur sédimentation dans la phase organique. À l’échelle moléculaire des analyses in-situ ont été réalisées par spectroscopie Raman sur des hydrates de méthane formés en présence des additifs AA. Ces essais ont mis en évidence la distribution des hydrates dans les phases organiques (gaz et condensat). Les observations par microscopie optique révèlent des morphologies d’hydrates comparables à celles obtenues en présence des additifs AAs dans les réacteursIn 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
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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.
Abstract (sommario):
La séparation du CO2 d'un mélange de gaz par cristallisation d'hydrates de gaz est un procédé qui pourrait à terme présenter une alternative intéressante aux techniques conventionnelles de capture du CO2. L'objectif de cette thèse était d'évaluer le potentiel de ce procédé "hydrates" pour séparer le CO2 d'un mélange CO2-CH4 riche en CO2. Nous avons étudié en particulier la sélectivité de la séparation vis-à-vis du CO2 et la cinétique de cristallisation des hydrates, ainsi que l'effet d'additifs thermodynamiques et cinétiques (et de certaines de leurs combinaisons) sur ces deux paramètres pour différentes conditions opératoires (pression, température, concentrations). Les expériences de formation/décomposition d’hydrates ont été réalisées en mode "batch" dans un réacteur haute pression faisant partie d'un pilote expérimental conçu et construit entièrement pendant cette thèse. Un modèle semi-empirique a été également développé pour estimer le taux de conversion de l’eau en hydrate et la composition des différentes phases en présence (hydrates, liquide et vapeur) à l'équilibre. Les résultats obtenus montrent que l'association du sodium dodécyl sulfate (SDS), utilisé en tant que promoteur cinétique, avec du tétrahydrofurane (THF), utilisé en tant que promoteur thermodynamique, permet d'obtenir des résultats intéressants en terme de quantité d'hydrates formés et de cinétique de formation. La sélectivité de la séparation vis-à-vis du CO2 reste cependant trop faible (en moyenne quatre molécules de CO2 piégées dans la structure de l'hydrate pour une de CH4) pour envisager d’utiliser ce procédé "hydrates" à plus grande échelle afin de séparer le CO2 de ce type de mélange de gazThe 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
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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.
Abstract (sommario):
Les hydrates de gaz sont des composés d'inclusion qui se forment en présence d'eau et de gaz à haute pression et basse température. La formation d'hydrates dans les pipes en production polyphasique conduit rapidement à un bouchage des conduites qui entraîne un arrêt de la production. Depuis quelques années, la recherche appliquée s'est orientée vers la mise au point d'inhibiteurs cinétiques. Ces additifs hydrosolubles sont des inhibiteurs de cristallisation. Ce travail a porté sur l'étude des mécanismes d'action d'une famille de copolymères AA/AMPS susceptibles de modifier la cristallisation de l'hydrate de méthane. Nous avons utilisé un appareillage qui permet d'obtenir des résultats macroscopiques (temps d'induction, vitesse de consommation de gaz) et microscopiques (granulométrie des particules d'hydrate). Nous avons étudié la cristallisation de l'hydrate de méthane sans additif au niveau macroscopique et au niveau microscopique à différentes pressions et vitesses d'agitation. Les influences de la composition des copolymères, de la masse moléculaire moyenne en poids et de la concentration massique en additif ont ensuite été étudiées. Des performances optimales pour un taux molaire de 50% en amps ont été mises en évidence. Par ailleurs, des concentrations minimum en additif ainsi que des masses moléculaires moyennes minimum sont nécessaires pour obtenir un effet cinétique sur les cristaux. Pour interpréter ces résultats, nous avons utilisé une modélisation. Il apparaît que le copolymère bloque la croissance en introduisant une zone morte. Puis, par un modelé fonde sur un bilan de population, nous avons établi une première identification de la source de cristaux sans et avec additifs. Enfin, la dernière partie de ce travail est relative à l'étude d'une formulation modelée à partir de copolymères AA/AMPS. Cette formulation présente une amélioration sensible des performances par rapport au polymère seul.
4
Pic, 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.
Abstract (sommario):
L'exploitation de gisements pétroliers off shore doit souvent faire face à des problèmes de colmatage de conduites, notamment dus à la cristallisation d'hydrates de gaz. Actuellement, les opérateurs ont recours à des additifs antigels, dont l'efficacité est limitée par des conditions d'exploitation et des normes anti-pollution de plus en plus sévères. Aussi les recherches s'orientent-elles vers une nouvelle classe d'inhibiteurs dits à faible dose. Afin de comprendre l'influence de tels additifs, nous avons réalisé un réacteur haute pression muni d'un dispositif d'injection de liquide et d'un capteur turbidimétrique in situ. L'accès à la granulométrie de la suspension aux premiers stades de la cristallisation et à la consommation de gaz permet de caractériser la cinétique de formation de l'hydrate de méthane. Nous avons développe un protocole opératoire original qui autorise une maîtrise accrue de la germination des cristaux, grâce à un ensemencement initial de la solution. Le temps de latence devient alors un paramètre représentatif de l'efficacité des inhibiteurs. Nous avons alors évalué l'influence des conditions de pression et d'agitation sur l'évolution de la population de cristaux en l'absence d'additif. Puis nous avons déterminé l'effet inhibiteur d'un additif cinétique modèle, la polyvinylpyrrolidone (pvp). Mis en solution avant la cristallisation, il allonge la période de latence, diminue la vitesse de consommation du gaz et ralentit la création de nouvelles particules durant plusieurs heures. Par contre, lorsque ce polymère est injecté dans le milieu en cours de formation, il n'affecte plus la cinétique de la réaction. Nous donnons enfin les bases d'un modèle relevant des processus élémentaires de cristallisation : germination, croissance et agglomération des particules. Confrontée aux données expérimentales, une étude paramétrique nous a permis d'émettre des hypothèses quant à l'effet des inhibiteurs cinétiques sur la formation des hydrates de gaz.
5
Pic, 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.
Abstract (sommario):
L'exploitation de gisements pétroliers off shore doit souvent faire face à des problèmes de colmatage de conduites, notamment dus à la cristallisation d'hydrates de gaz. Actuellement, les opérateurs ont recours à des additifs antigels, dont l'efficacité est limitée par des conditions d'exploitation et des normes anti-pollution de plus en plus sévères. Aussi les recherches s'orientent-elles vers une nouvelle classe d'inhibiteurs dits à faible dose. Afin de comprendre l'influence de tels additifs, nous avons réalisé un réacteur haute pression muni d'un dispositif d'injection de liquide et d'un capteur turbidimétrique in situ. L'accès à la granulométrie de la suspension aux premiers stades de la cristallisation et à la consommation de gaz permet de caractériser la cinétique de formation de l'hydrate de méthane. Nous avons développé un protocole opératoire original qui autorise une maîtrise accrue de la germination des cristaux, grâce à un ensemencement initial de la solution. Le temps de latence devient alors un paramètre représentatif de l'efficacité des inhibiteurs. Nous avons alors évalué l'influence des conditions de pression et d'agitation sur l'évolution de la population de cristaux en l'absence d'additif. Puis nous avons déterminé l'effet inhibiteur d'un additif cinétique modèle, la polyvinylpyrrolidone (PVP). Mis en solution avant la cristallisation, il allonge la période de latence, diminue la vitesse de consommation du gaz et ralentit la création de nouvelles particules durant plusieurs heures. Par contre, lorsque ce polymère est injecté dans le milieu en cours de formation, il n'affecte plus la cinétique de la réaction. Nous donnons enfin les bases d'un modèle relevant des processus élémentaires de cristallisation : germination, croissance et agglomération des particules. Confrontée aux données expérimentales, une étude paramétrique nous a permis d'émettre des hypothèses quant à l'effet des inhibiteurs cinétiques sur la formation des hydrates de gaz.
6
Sales, 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.
Abstract (sommario):
Le biogaz, constitué essentiellement de méthane et de dioxyde de carbone, représente une voie alternative aux sources d’énergies fossiles. Pour être valorisé le mélange doit être séparé dans un procédé de séparation de gaz. Ces dernières années, un nouveau procédé basé sur la formation d'hydrates de gaz (GSHF) a suscité une attention particulière dans la communauté scientifique. Basé sur une transition de phase hydrate – liquide – vapeur conduite en présence de promoteurs thermodynamiques, la purification est supposée demander moins d’énergie et moins de réactifs dangereux pour l’environnement que les procédés chimiques traditionnels comme l’absorption dans des solutions d’amines. Une connaissance des équilibres de phase dans les systèmes eau + gaz + additifs est essentielle à la validation du procédé. Dans ce projet, nous avons étudié quatre promoteurs, le bromure de trétrabutylammonium (TBAB), le bromure de tétrabutylphosphonium (TBPB), l’oxyde de tributylphosphine (TBPO) et le tétrahydropyrane (THP), qui ont pour buts d’abaisser la consommation d'énergie et d’améliorer la cinétique et la sélectivité du procédé. Une partie de ce projet a été consacrée à déterminer les conditions d'équilibre d'hydrates de gaz en présence de ces promoteurs et différentes phases gaz (CO2, CH4 et biogaz simulé). Les méthodes de calorimétrie différentielle à balayage (DSC) ont été appliquées pour mesurer les températures de transition de phase. De nouvelles données d'équilibre de phases ont été déterminées pour les systèmes hydrates de gaz + promoteurs. Dans la deuxième partie du projet, nous avons effectué des mesures quantitatives dans un réacteur instrumenté afin d'évaluer le procédé GSFH pour la valorisation du biogaz. Chaque promoteur a été évalué tant sur le plan de la cinétique (temps, d’induction, vitesse de croissance cristalline) que sur celui de la thermodynamique (quantité de gaz piégé, sélectivité). L'optimisation du programme de formation / dissociation des hydrates a montré d'excellents résultats en termes de cinétiqueBiogas 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
7
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.
Abstract (sommario):
Le biogaz, constitué essentiellement de méthane et de dioxyde de carbone, représente une voie alternative aux sources d’énergies fossiles. Pour être valorisé le mélange doit être séparé dans un procédé de séparation de gaz. Ces dernières années, un nouveau procédé basé sur la formation d'hydrates de gaz (GSHF) a suscité une attention particulière dans la communauté scientifique. Basé sur une transition de phase hydrate – liquide – vapeur conduite en présence de promoteurs thermodynamiques, la purification est supposée demander moins d’énergie et moins de réactifs dangereux pour l’environnement que les procédés chimiques traditionnels comme l’absorption dans des solutions d’amines. Une connaissance des équilibres de phase dans les systèmes eau + gaz + additifs est essentielle à la validation du procédé. Dans ce projet, nous avons étudié quatre promoteurs, le bromure de trétrabutylammonium (TBAB), le bromure de tétrabutylphosphonium (TBPB), l’oxyde de tributylphosphine (TBPO) et le tétrahydropyrane (THP), qui ont pour buts d’abaisser la consommation d'énergie et d’améliorer la cinétique et la sélectivité du procédé. Une partie de ce projet a été consacrée à déterminer les conditions d'équilibre d'hydrates de gaz en présence de ces promoteurs et différentes phases gaz (CO2, CH4 et biogaz simulé). Les méthodes de calorimétrie différentielle à balayage (DSC) ont été appliquées pour mesurer les températures de transition de phase. De nouvelles données d'équilibre de phases ont été déterminées pour les systèmes hydrates de gaz + promoteurs. Dans la deuxième partie du projet, nous avons effectué des mesures quantitatives dans un réacteur instrumenté afin d'évaluer le procédé GSFH pour la valorisation du biogaz. Chaque promoteur a été évalué tant sur le plan de la cinétique (temps, d’induction, vitesse de croissance cristalline) que sur celui de la thermodynamique (quantité de gaz piégé, sélectivité). L'optimisation du programme de formation / dissociation des hydrates a montré d'excellents résultats en termes de cinétiqueBiogas 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
8
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.
Abstract (sommario):
La cristallisation des hydrates pendant la production de pétrole est une source de risques, surtout liés au bouchage des lignes de production dû à l’agglomération des hydrates. Pendant l'extraction de pétrole, l'huile et l'eau circulent dans le pipeline et forment une émulsion instable. La phase eau se combine avec les composants d'hydrocarbures légers et peut former des hydrates. La cristallisation des hydrates a été intensivement étudiée, principalement à faible fraction d’eau. Cependant, lorsque le champ de pétrole devient mature, la fraction d’eau augmente et peut devenir la phase dominante, un système peu étudié concernant à la formation d'hydrates. Plusieurs techniques peuvent être combinées pour éviter ou remédier la formation d'hydrates. Récemment, une nouvelle classe d'additifs a commencé à être étudiée : Inhibiteurs d'Hydrates à Bas Dosage (LDHI), divisés en Inhibiteurs Cinétiques (KHI-LDHI) et anti-agglomérants (AA-LDHI).Ce travail est une étude paramétrique de la formation d'hydrates à partir de l'émulsion, en variant la fraction d’eau, le débit, en absence et en présence d’AA-LDHI. Les expériences ont été réalisées sur la boucle d'écoulement Archimède, qui est en mesure de reproduire les conditions de la mer profonde. L'objectif de cette étude est d'améliorer la compréhension de la formation d'hydrate et de comprendre comment l'additif dispersant évite l'agglomération. Pour ce faire, un modèle comportemental de la cristallisation pour les systèmes sans et avec additif a été développé. Il a également été proposé une technique pour déterminer la phase continue du système et un mécanisme d'action pour l'anti-agglomérant a été suggéréCrystallization 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
9
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.
Abstract (sommario):
Dans les conduites pétrolières sous-marines ou dans celles de gaz, la formation des hydrates de gaz est un problème majeur. La présence de nouvelles particules solides formées à partir des molécules d'eau et des hydrocarbures légers (méthane, éthane. . . ) sous haute pression et basse température au sein d’un effluent qui au départ est liquide, a pour effet d’augmenter brutalement la viscosité de l’ensemble, ce qui gène encore le flux dans son écoulement. Au bout du compte on peut observer un blocage complet de la conduite. Pour les éliminer après leur formation, on peut avoir recours à un procédé de dépressurisation symétrique. Pour étudier ce problème, nous avons utilisé deux appareillages. Avec ces deux systèmes, nous avons obtenu des bouchons de différentes tailles (7 cm, 10,75 cm et 12 cm de diamètre). Ils ont une porosité entre 0,25 et 0,9. Nous avons proposé un modèle numérique qui est basé sur la méthode d’enthalpie en milieu infini selon l’axe de symétrie radiale et pour des coordonnées cylindriques. Le modèle utilise une équation de la loi de Fourier modifiée afin de déterminer l’enthalpie en toutes positions de la phase liquide. Ce modèle intègre la porosité du bouchon, la structure des hydrates ainsi que la géométrie de la conduite. Ce modèle est validé par les données expérimentales présentes dans la littérature et nos résultats expérimentaux. Une méthode quasi-stationnaire est aussi proposée permettant de simplifier l’estimation de la durée de dissociation. L’erreur moyenne du temps de dissociation obtenu entre les deux méthodes est environ de 2,7 % pour une température comprise dans l’intervalle [273,15 K; 277,15 K] et une porosité entre 0,3 et 0,9Natural 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
10
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.
Abstract (sommario):
La demande en énergies fossiles a connu une forte croissance au cours du vingtième siècle et représente aujourd'hui 80% de la consommation énergétique mondiale. Pour répondre à la demande, les industries pétrolières et gazières s'orientent vers de nouvelles sources. 40% des réserves de gaz contiennent un pourcentage important (jusqu'à 20%) de gaz acides (dioxyde de carbone et sulfure d'hydrogène). La production de ces gaz à forte teneur en gaz acides représente un défi pour les industries, étant donné la toxicité du sulfure d'hydrogène et la forte probabilité de corrosion des pipelines en présence d'eau (naturellement produite avec le gaz naturel). D'autre part, l'utilisation des énergies fossiles conduit au changement climatique avec des émissions importantes de dioxyde de carbone dans l'atmosphère. Le captage et le stockage du CO2 semble être un procédé prometteur. De l'eau est souvent présente lors du transport du gaz naturel et du CO2 capturé. Lors des étapes de production et de transport, les conditions de température et de pression sont sujettes au changement. La condensation de l'eau (à l'origine de la corrosion et donc d'une rupture possible des pipelines) et à la formation de glace et/ou d'hydrates en sont les conséquences principales. Or la formation d'hydrates est un sérieux problème avec un risque de blocage des pipelines. Pour éviter la formation des hydrates, des inhibiteurs chimiques sont utilisés. Il est donc indispensable de bien connaitre les équilibres entre phases pour les différents mélanges considérés pour un fonctionnement et une production en toute sécuritéThe 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
Libri sul tema "Hydrates de gaz naturel – Additifs":
1
R, Dallimore S., Uchida T, Collett T. S e Geological Survey of Canada, a cura di. Scientific results from JAPEX/JNOC/GSC Mallik 2L-38 Gas Hydrate Research Well, Mackenzie Delta, Northwest Territories, Canada. [Ottawa]: Geological Survey of Canada, 1999.
2
Carroll, John J. Natural gas hydrates: A guide for engineers. Amsterdam: Gulf Professional Pub., 2003.
3
Max, M. D. Natural Gas Hydrate in Oceanic and Permafrost Environments (Coastal Systems and Continental Margins). Springer, 2003.
4
Broseta, Daniel, Livio Ruffine e Arnaud Desmedt. Gas Hydrates 1: Fundamentals, Characterization and Modeling. Wiley & Sons, Incorporated, John, 2017.
5
Broseta, Daniel, Livio Ruffine e Arnaud Desmedt. Gas Hydrates 1: Fundamentals, Characterization and Modeling. Wiley & Sons, Incorporated, John, 2017.
6
Broseta, Daniel, Livio Ruffine e Arnaud Desmedt. Gas Hydrates 1: Fundamentals, Characterization and Modeling. Wiley & Sons, Incorporated, John, 2017.
7
Sloan, Jr E. Dendy, e Carolyn Koh. Clathrate Hydrates of Natural Gases, Third Edition (Chemical Industries Series). 3a ed. CRC, 2007.
8
Broseta, Daniel, Livio Ruffine e Arnaud Desmedt. Gas Hydrates 2: Geoscience Issues and Potential Industrial Applications. Wiley & Sons, Incorporated, John, 2018.
9
Broseta, Daniel, Livio Ruffine e Arnaud Desmedt. Gas Hydrates 2: Geoscience Issues and Potential Industrial Applications. Wiley & Sons, Incorporated, John, 2018.
10
Broseta, Daniel, Livio Ruffine e Arnaud Desmedt. Gas Hydrates 2: Geoscience Issues and Potential Industrial Applications. Wiley & Sons, Incorporated, John, 2018.
Capitoli di libri sul tema "Hydrates de gaz naturel – Additifs":
1
Ketzer, João Marcelo, Adriano Viana, Dennis Miller, Adolpho Augustin, Frederico Rodrigues, Daniel Praeg e José Cupertino. "Hidratos de Gás Na Margem Continental Brasileira". In Recursos Minerais Marinhos. Sociedade Brasileira de Geofísica - SBGf, 2023. http://dx.doi.org/10.22564/sbgfbook.cad5.2023.cap10.
Abstract (sommario):
O presente capítulo faz uma introdução geral sobre o tema hidratos de gás naturais, i.e., que ocorrem nos sedimentos, apresentando os tipos existentes, como se formam, os principais gases envolvidos, a sua importância econômica e ambiental (incluindo mudança climática e como geohazards), além de suas ocorrências naturais no mundo. A seguir é apresentado um breve histórico dos estudos e da exploração de hidratos de gás no Brasil, seguido de uma descrição das ocorrências naturais confirmadas no país, no leque do Amazonas (Bacia da Foz do Amazonas) e no Cone de Rio Grande (Bacia de Pelotas). Por fim é apresentada uma breve comparação entre as duas ocorrências e uma discussão sobre o desenvolvimento futuro da exploração de hidratos de gás no país. Palavras-chave: metano, leque do Amazonas, Cone de Rio Grande, recurso energético, mudança climática, geohazard. Abstract This chapter starts with an introduction of the topic of natural gas hydrates, presenting the main existing types, how they form, the main gases involved in their formation, their economic and environmental (including climate change and as geohazards) importance, in addition to their worldwide natural occurrences. Also included is a brief history of the study and exploration of gas hydrates in Brazil, and a description of the two confirmed occurrences in the country: The Amazon fan (Foz do Amazonas basin) and the Rio Grande Cone (Pelotas Basin). The chapter ends with a brief comparison between the two occurrences and a discussion about the future development of the exploration for gas hydrates in the country. Keywords: methane, Amazon fan, Rio Grande Cone, energy resource, climate change, geohazard.
2
Gorbachev, Boris Gusev, Victor Kuzin, Shengli Xie e Dong Yue. "Preface". In Hybrid Methods of Big Data Analysis and Applications, ix—xviii. Creosar Publishing, 2022. http://dx.doi.org/10.57118/creosar/978-1-915740-01-4_0.
Abstract (sommario):
This volume describes the solution of problems of Big Data intellectual analysis, control, design and optimization. Big Data - technologies that extract maximum benefit from big data, which are widespread in all spheres. Starting with an official introduction to the basics of algorithm hybridization, this book combines many different aspects of current research on hybrid technologies, such as deep neural networks, fuzzy neural networks, multi-MISO ANFIS, fuzzy C-means, conditional disentangled networks, generative adversarial networks, finite difference method and enthalpy method. The book also covers a wide range of applications and implementation problems, from pattern recognition and image generation to intelligent forecasting problems, automation of production in technical applications (3D-analysis, forecasting of distributed photovoltaic systems and loads) with due attention to modeling. It covers a wide range of applications in the field of Big Data analysis, as well as Data Mining. In addition to the traditional tasks of classification, clustering, forecasting, it also discusses original approaches to hybrid optimization and control in the tasks of multi-object optimization for smart grid, natural gas hydrate wellbore, parallel search for optimal technological parameters of the non-consumable electrode welding. The articles are arranged in five thematic topics, I) Strongly coupled (functional) hybrid methods (articles 1-3); II) Loosely coupled (functional) hybrid methods (articles 4-5); III) Transformational hybrid methods (articles 6-7); IV) Integrated methods (articles 8-12) and V) Distributed hybrid intelligent methods (article 13).
Atti di convegni sul tema "Hydrates de gaz naturel – Additifs":
1
Delgado-Linares, Jose G., Ahmad A. A. Majid, Luis E. Zerpa e Carolyn A. Koh. "Reducing THI Injection and Gas Hydrate Agglomeration by Under-Inhibition of Crude Oil Systems". In Offshore Technology Conference. OTC, 2021. http://dx.doi.org/10.4043/31161-ms.
Abstract (sommario):
Abstract Gas hydrates constitute a serious flow assurance problem. Over the last decades, industry has faced this problem by using avoidance methods (e.g. injection of thermodynamic hydrate inhibitors) and management strategies (e.g. addition of hydrate anti-agglomerants). In the former, hydrates are completely avoided by shifting the hydrate boundary towards higher pressure and lower temperatures; in the latter, hydrates are allowed to form but their tendency to agglomerate is reduced. It should be noted that some crude oils are naturally able to avoid hydrate agglomeration, this non-plugging tendency may originate from the surfactant-like behavior of fractions like asphaltenes and acids. Recent works have shown that the natural non-plugging potential of certain oils can be affected by the addition of polar molecules like alcohols. There is another strategy for managing hydrate that consist of the addition of THIs at a concentration lower that the one required to full hydrate inhibition. In this case, hydrates are under-inhibited. Studies carried out on hydrate agglomerating systems have shown that under-inhibition might prevent hydrate agglomeration only in a specific range of THI concentrations and sub-cooling; however, work on non-plugging oils is scarce. In this paper, the hydrate agglomeration of two crude oils under-inhibited with methanol and MEG was evaluated through a visual rocking cell apparatus and a high-pressure rheometer. Results showed that THIs and the crude oil's natural surfactants were capable of acting synergistically in reducing hydrate agglomeration and improving the system flowability.
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Kar, Aritra, Palash Acharya, Awan Bhati, Arjang Shahriari, Ashish Mhahdeshwar, Timothy A. Barckholtz e Vaibhav Bahadur. "Modeling the Influence of Heat Transfer on Gas Hydrate Formation". In ASME 2022 Heat Transfer Summer Conference collocated with the ASME 2022 16th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/ht2022-79744.
Abstract (sommario):
Abstract Gas hydrates are crystalline structures of water and gas which form at high pressures and low temperatures. Hydrates have important applications in carbon sequestration, desalination, gas separation, gas transportation and influence flow assurance in oil-gas production. Formation of gas hydrates involves mass diffusion, chemical kinetics and phase change (which necessitates removal of the heat of hydrate formation). When hydrates are synthesized artificially inside reactors, the heat released raises the temperature of the water inside the reactor and reduces the rate of hydrate formation (since the driving force is reduced). An examination of literature shows that there is inadequate understanding of the coupling between heat and mass transfer during hydrate formation. Current models treat heat and mass transfer separately during hydrate formation. In this study, we develop a first principles-based mathematical framework to couple heat and mass transfer during hydrate formation. Our model explores the difference between “actual subcooling” and “apparent subcooling” in the hydrate forming system. The apparent subcooling depends on the targeted reactor temperature and is supposedly, the driving force for hydrate growth. However, due to the increase in temperature of the reactor, the actual subcooling is lower than the apparent subcooling. All these effects are modeled for a 1-D hydrate forming reactor. Results of our simulations are compared with some experimental observations from literature. We also present mathematical scaling to determine the temperature rise in a hydrate-forming reactor. In addition to artificial synthesis of hydrates, the mathematical framework developed can also be applied to other hydrate forming systems (flow assurance, hydrate formation in nature).
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Sahari Moghaddam, Farzan, Maziyar Mahmoodi, Marziyeh Zare, Fatemeh Goodarzi, Majid Abdi e Lesley James. "Natural Gas Hydrate Equilibria in Brine Including the Effect of Inhibitors on Hydrate Formation". In SPE Canadian Energy Technology Conference. SPE, 2022. http://dx.doi.org/10.2118/208890-ms.
Abstract (sommario):
Abstract Preventing hydrate formation is critical to safely and economically manage subsea tiebacks. Thermodynamic Hydrate Inhibitors (THI) and Low Dosage Hydrate Inhibitors (LDHI) help manage hydrate formation. Here, we use a novel isothermal approach using a PVT cell to experimentally find the hydrate equilibrium point of natural gas and brine. In addition, a constant temperature and pressure condition is used to compare hydrate formation with and without hydrate inhibitors. First, to better understand the novel isothermal technique, natural gas-brine equilibrium experiments were conducted. Secondly, a constant pressure and temperature approach is used to investigate Kinetic Hydrate Inhibitors (KHIs) and low dosage methanol performance on hydrate formation. The formation and dissociation points are detected through a sudden drop or peak in the pressure profile, respectively, and by visual observation. To evaluate inhibitor performance, the experiments were conducted at challenging temperatures between -0.5°C to 3°C, applicable to the environment offshore Newfoundland and Labrador. Two commercial KHIs and one THI were tested. Both KHIs showed good performance up to certain level of subcooling according to their concentration. However, KHI-B performed better at inhibiting hydrates compared to KHI-A despite its lower concentrations compared to KHI-A. The induction time for 1 wt% KHI-A under 10°C subcooling at a temperature of 0.75°C was 311 min. The induction time for 1 wt% KHI-B under 12°C subcooling at a temperature of 2.66°C was 184 min. Yet, in the case of KHI B, with half the concentration (0.5 wt%), no hydrate formed at temperature of 1.21°C and 10°C subcooling. Low dosage methanol (a common THI) was also assessed. Although the induction time under 10.36°C subcooling and constant temperature of −0.43°C was only 47 min, no hydrate formed within 22 hours at −0.12°C under 7.5°C subcooling. This work uses a novel experimental isothermal approach by PVT cell to investigate hydrate equilibrium and the effectiveness of different inhibitors. Hence, a better understanding of natural gas hydrate equilibrium in brine is developed. Based on significant costs associated with injecting high quantities of THI (e.g., methanol) to prevent hydrate formation, this work also compares the performance of KHIs and low dosage THI (methanol).
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Aregbe, Azeez Gbenga, e Ayoola Idris Fadeyi. "A Comprehensive Review on CO2/N2 Mixture Injection for Methane Gas Recovery in Hydrate Reservoirs". In SPE Nigeria Annual International Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/207092-ms.
Abstract (sommario):
Abstract Clathrate hydrates are non-stoichiometric compounds of water and gas molecules coexisting at relatively low temperatures and high pressures. The gas molecules are trapped in cage-like structures of the water molecules by hydrogen bonds. There are several hydrate deposits in permafrost and oceanic sediments with an enormous amount of energy. The energy content of methane in hydrate reservoirs is considered to be up to 50 times that of conventional petroleum resources, with about 2,500 to 20,000 trillion m3 of methane gas. More than 220 hydrate deposits in permafrost and oceanic sediments have been identified to date. The exploration and production of these deposits to recover the trapped methane gas could overcome the world energy challenges and create a sustainable energy future. Furthermore, global warming is a major issue facing the world at large and it is caused by greenhouse gas emissions such as carbon dioxide. As a result, researchers and organizations have proposed various methods of reducing the emission of carbon dioxide gas. One of the proposed methods is the geological storage of carbon dioxide in depleted oil and gas reservoirs, oceanic sediments, deep saline aquifers, and depleted hydrate deposits. Studies have shown that there is the possibility of methane gas production and carbon dioxide storage in hydrate reservoirs using the injection of carbon dioxide and nitrogen gas mixture. However, the conventional hydrocarbon production methods cannot be used for the hydrate reservoirs due to the nature of these reservoirs. In addition, thermal stimulation and depressurization are not effective methods for methane gas production and carbon sequestration in hydrate-bearing sediments. Therefore, the gas replacement method for methane production and carbon dioxide storage in clathrate hydrate is investigated in this paper. The research studies (experiments, modeling/simulation, and field tests) on CO2/N2 gas mixture injection for the optimization of methane gas recovery in hydrate reservoirs are reviewed. It was discovered that the injection of the gas mixture enhanced the recovery process by replacing methane gas in the small and large cages of the hydrate. Also, the presence of N2 molecules significantly increased fluid injectivity and methane recovery rate. In addition, a significant amount of free water was not released and the hydrate phase was stable during the replacement process. It is an effective method for permanent storage of carbon dioxide in the hydrate layer. However, further research studies on the effects of gas composition, particle size, and gas transport on the replacement process and swapping rate are required.
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Sayed, Mohammed, Rajesh Saini, Eyad AlAli, Rajendra Kalgaonkar e Ahmed Arnous. "From Laboratory to Field Applications: A Safer Gas Hydrate Dissolver to Replace Methanol". In Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/31998-ms.
Abstract (sommario):
Abstract Low-molecular-weight hydrocarbon gases, such as methane and ethane, along with other low-molecular-weight species, such as CO2 and H2S, exist within the gas stream flowing through the pipelines used to transport natural gas and crude oils. Under certain conditions of low temperature and high pressure, and in the presence of free water molecules, gas-hydrate crystals will start to form. These gas hydrate crystals may accumulate and cause partial or complete plugging of the pipeline in the vertical or horizontal sections of the pipe. Methanol was previously found to be the only effective chemical able to clear gas hydrate plugs in many cases. The low flashpoint of methanol makes it unsafe to be pumped or stored in large volumes in hot regions such as in the Middle East. The main objective of the current work is to develop a safer chemical treatment with a higher flashpoint for the dissolution/mitigation of in-place gas hydrate plugs in pipelines. The parameters that make methanol an effective hydrate dissolver were investigated before development of the new hydrate dissolver. Methanol has a very low freezing point (-90°C) and is completely miscible with water. Solvent-based and aqueous-based formulations were chosen while considering parameters such as miscibility with water, freezing point, viscosity, and availability. The performance of these formulations was evaluated using a see-through gas hydrate cell. Pressure and temperature were modified to allow the formation of hydrates at simulated field conditions. Representative gas and water compositions were used in the experiments to form gas hydrate inside the gas hydrate cell. Hydrate formation can be detected either by detecting the change in torque on the stirring shaft or by visual inspection of the cell. The performance of these formulations was evaluated and compared to methanol. Two solvent-based formulations and two aqueous-based treatments met the flashpoint requirement and were effective in dissolving hydrate plugs at similar dosage when compared to methanol. These formulations proved to dissolve gas hydrate plugs in similar or less time than methanol. Two field trials were conducted to test one of the aqueous-based treatments and the outcome showed that the hydrate plug was dissolved in less than 17 minutes from the moment the aqueous solution was injected. The tested formulations have been shown to not only work as a dissolver, but also as an inhibitor to prevent the fresh formation of hydrate downstream. In addition to improving the performance of dissolving gas hydrate plugs in the pipelines, the use of these treatments has enabled safer operations in the field.
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Sayed, Mohammed, Rajesh Saini, Eyad AlAli, Rajendra Kalgaonkar e Ahmed Arnous. "From Laboratory to Field Applications: A Safer Gas Hydrate Dissolver to Replace Methanol". In Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/31998-ms.
Abstract (sommario):
Abstract Low-molecular-weight hydrocarbon gases, such as methane and ethane, along with other low-molecular-weight species, such as CO2 and H2S, exist within the gas stream flowing through the pipelines used to transport natural gas and crude oils. Under certain conditions of low temperature and high pressure, and in the presence of free water molecules, gas-hydrate crystals will start to form. These gas hydrate crystals may accumulate and cause partial or complete plugging of the pipeline in the vertical or horizontal sections of the pipe. Methanol was previously found to be the only effective chemical able to clear gas hydrate plugs in many cases. The low flashpoint of methanol makes it unsafe to be pumped or stored in large volumes in hot regions such as in the Middle East. The main objective of the current work is to develop a safer chemical treatment with a higher flashpoint for the dissolution/mitigation of in-place gas hydrate plugs in pipelines. The parameters that make methanol an effective hydrate dissolver were investigated before development of the new hydrate dissolver. Methanol has a very low freezing point (-90°C) and is completely miscible with water. Solvent-based and aqueous-based formulations were chosen while considering parameters such as miscibility with water, freezing point, viscosity, and availability. The performance of these formulations was evaluated using a see-through gas hydrate cell. Pressure and temperature were modified to allow the formation of hydrates at simulated field conditions. Representative gas and water compositions were used in the experiments to form gas hydrate inside the gas hydrate cell. Hydrate formation can be detected either by detecting the change in torque on the stirring shaft or by visual inspection of the cell. The performance of these formulations was evaluated and compared to methanol. Two solvent-based formulations and two aqueous-based treatments met the flashpoint requirement and were effective in dissolving hydrate plugs at similar dosage when compared to methanol. These formulations proved to dissolve gas hydrate plugs in similar or less time than methanol. Two field trials were conducted to test one of the aqueous-based treatments and the outcome showed that the hydrate plug was dissolved in less than 17 minutes from the moment the aqueous solution was injected. The tested formulations have been shown to not only work as a dissolver, but also as an inhibitor to prevent the fresh formation of hydrate downstream. In addition to improving the performance of dissolving gas hydrate plugs in the pipelines, the use of these treatments has enabled safer operations in the field.
7
Aminnaji, Morteza, Alfred Hase e Laura Crombie. "Anti-Agglomerants: Study of Hydrate Structural, Gas Composition, Hydrate Amount, and Water Cut Effect". In International Petroleum Technology Conference. IPTC, 2023. http://dx.doi.org/10.2523/iptc-22765-ms.
Abstract (sommario):
Abstract Kinetic hydrate inhibitors (KHIs) and anti-agglomerants (AAs) – known as low dosage hydrate inhibitors (LDHIs) – have been used widely for gas hydrate prevention in oil and gas operations. They offer significant advantages over thermodynamic inhibitors (e.g., methanol and glycols). While significant works have been done on KHIs evaluation, AAs suffer from their evaluation in terms of hydrate structural effect, gas composition, water cut, and hydrate amount, which are the main objectives of this work. A Shut-in-Restart procedure was carried out to experimentally evaluate (using a visual rocking cell) various commercial AAs in different gas compositions (from a simple methane system to multicomponent natural gas systems). The kinetics of hydrate growth rate and the amount of hydrate formation in the presence of AAs were also analysed using the recorded pressure-temperature data. The amount of hydrate formation (WCH: percentage of water converted to hydrate) was also calculated by pressure drop and establishing the pressure-temperature hydrate flash. The experimental results from the step heating equilibrium point measurement suggest the formation of multiple hydrate structures or phases in order of thermodynamic stability rather than the formation of simple structure II hydrate in the multicomponent natural gas system. The initial findings of experimental studies show that the performance of AAs is not identical for different gas compositions. This is potentially due to the hydrate structural effect on AAs performance. For example, while a commercially available AA (as tested here) could not prevent hydrate agglomeration/blockage in the methane system (plugging occurred after 2% hydrate formed in the system), it showed a much better performance in the natural gas systems. In addition, while hydrate plugging was not observed in the visual rocking cell in the rich natural gas system with AA (at a high subcooling temperature of ∼15°C), some hydrate agglomeration and hydrate plugging were observed for the lean natural gas system at the same subcooling temperature. It is speculated that methane hydrate structure I is potentially the main reason for hydrate plugging and failure of AAs. Finally, the results indicate that water cut%, gas composition, and AAs concentration have a significant effect on hydrate growth rate and hydrate plugging. In addition to increasing confidence in AAs field use, findings potentially have novel applications with respect to hydrate structural effect on plugging and hydrate plug calculation. A robust pressure-temperature hydrate flash calculation is required to calculate the percent of water converted to hydrate during hydrate growth in the presence of AAs.
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Suri, Ajay, e Ankur Singh. "Synergistic Hydrate Inhibition by Iota-Carrageenan with Kinetic Hydrate Inhibitors". In Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213610-ms.
Abstract (sommario):
Abstract The hydrate-inhibiting performance of a natural plant-based polysaccharide iota-carrageenan is evaluated as a standalone inhibitor and as a synergist with two well-known kinetic hydrate inhibitors (KHIs), polyvinyl caprolactam (PVCap) and polyvinylpyrrolidone (PVP), in order to achieve a higher hydrate inhibition performance. The hydrate inhibiting performance is assessed experimentally by measuring the induction time (IT) required for measurable hydrate formation and by the average hydrate growth rate (HGR) after measurable hydrate formation using a standard constant cooling rate of 1°C/h. Three inhibitor dosages at 0.5 wt% and 1 wt% are tested for the methane hydrate formation at 7.6 MPa and hydrate equilibrium temperature of 10.45°C. Synergy evaluation between the common KHIs and iota-carrageenan is done by making 50:50 ratio blends of iota-carrageenan with PVP and PVCap respectively (half iota-carrageenan and half KHI by wt%) and their performance is compared with the performance of individual PVP and PVCap performance at the same total inhibitor concentration for fair comparison. The individual inhibitor experimental results at 0.5-1 wt% showed that iota-carrageenan has a lower IT (around 4.5-5 h) than PVP (around 5.5-6.3 h) and PVCap (around 6.5-7.1 h), but has a lower average hydrate growth rate (HGR) between 0.07-0.08 m/h compared to PVCap (0.11-0.12 m/h) and PVP (0.13-0.18 m/h). The experimental results for the 50:50 blends of i-crgn with PVP and PVCap at a total concentration of 0.5-1 wt%, showed significant boost in the ITs (8.1-10.2 h for PVP and i-crgn blend) and (8.7-11.2 h for PVCap and i-crgn blend). These values were up 33-57% at the same total concentration of the individual inhibitor and the blend. The blends also have a much lower HGR with values 0.04-0.12 m/h at a total concentration of 0.5-1 wt% which is 16 - 64% lower than the individual HGRs of PVP and PVCap. Hence, iota-carrageenan, a natural, non-toxic, sustainable chemical can be used as hydrate inhibiting synergist additive to PVP and PVCap and other commercial hydrate inhibitors for enhanced hydrate inhibition performance and biodegradability.
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Chen, Mingqiang, Qingping Li, Shouwei Zhou, Weixin Pang, Xin Lyu, Junlong Zhu, Qiang Fu, Chaohui Lyu e Yang Ge. "Dynamic Characterization of Pore Structures in Hydrate-Bearing Sediments During Hydrate Phase Transition". In SPE Annual Technical Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/214854-ms.
Abstract (sommario):
Abstract Natural gas hydrate widely distributed in marine sediments and permafrost has brought great attention due to its large reserves. Unlike conventional reservoirs, the effective pore structures vary from time and space due to hydrate dissociation and secondary formation in the development, which produces significant impacts on gas flow and production. Therefore, figuring out the evolution of dynamic pore structures is of great importance for the efficient development of hydrate deposits. In this work, excess-water hydrate formation method was combined with micro-computed tomography to study hydrate transition effects on the evolution of dynamic pore structures. Gas state equation and chemical reaction dynamics were combined for separating the representative 3D images at different stages of hydrate formation into four phases, which are respectively hydrate, water, gas and solid skeleton. Hydrate pore habit evolution, formation characteristics, spatial distribution heterogeneity and its effect on the effective porosity variation were studied in detail. Afterwards, a modified maximal ball method was employed to extract hydrate-bearing pore networks at different stages of hydrate phase transition. Hydrate phase transition effects on the effective pore and throat radii distributions, pore and throat cross-sections, throat lengths and distance among connected pore bodies, as well as pore topology were further investigated based on the extracted networks. Results show that hydrate pore habit varies in porous media during hydrate formation with the main pore habit of pore filling mode. Hydrate spatial distribution exhibits some heterogeneity, causing diverse hydrate saturation at different layers during hydrate phase transition. Hydrate disrupted pore integrity to some extent, resulting in more extracted pore bodies and throats with increased hydrate saturation. In addition, hydrate phase transition reduces pore-throat radii and distribution regularity to different degrees, and results in more irregular pore-throat morphology, decrease of throat length and distance among connected pore bodies as well as poorer connectivity at the same time. This study provides a novel insight in better understanding the evolution of dynamic pore structures and lays a good foundation for the effective development of natural gas hydrate deposits.
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Ran, Lina, Shuang Liu, Qiqi Wanyan, Erdong Yao e Song Bai. "Optimization and Evaluation of Chemical Shrinking Agent for Deposits in Salt Cavern Gas Storage". In ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/omae2021-62735.
Abstract (sommario):
Abstract Salt cavern gas storage is an important strategic method to shave the fluctuation of supply-demand of natural gas in China. However, due to low grades of salt beds, there remains lots of insoluble sediments accounting for 1/3 up to 2/3 of the storage capacity at the bottom of cavity. The use of chemical agent with the function of swelled-clay-shrinking is an effective method for enlarging actual cavity volume. Clay swelling and physical deposits experiments were conducted to select the suitable chemical shrinking agent and study the relation between salt rock and agent. A device simulating the leaching process of insoluble sediments was developed to evaluate different factors on residue deposits and XRD (X-Ray Diffraction) was used to analyze mineral compositions of various salt caverns. The results showed that the main controlling factor for the volume swelling of the bottom insoluble sediments in the salt cavity is the electrostatic repulsion. These hydrated cuttings carry a negative charge leading to the electrostatic repulsion between each other, which promotes the loose accumulations of these physical deposits. The relation between rock and shrinking agent is clarified and the selected chemical agent has an excellent adaptation in salt cavern gas storages through the tests above. In addition, the result provides an experimental basis for minimizing the volume of the salt carven sediments to store more natural gas.