Academic literature on the topic 'Hydrates'
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Journal articles on the topic "Hydrates"
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Daghash, Shaden M., Phillip Servio, and Alejandro D. Rey. "From Infrared Spectra to Macroscopic Mechanical Properties of sH Gas Hydrates through Atomistic Calculations." Molecules 25, no. 23 (November 27, 2020): 5568. http://dx.doi.org/10.3390/molecules25235568.
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The vibrational characteristics of gas hydrates are key identifying molecular features of their structure and chemical composition. Density functional theory (DFT)-based IR spectra are one of the efficient tools that can be used to distinguish the vibrational signatures of gas hydrates. In this work, ab initio DFT-based IR technique is applied to analyze the vibrational and mechanical features of structure-H (sH) gas hydrate. IR spectra of different sH hydrates are obtained at 0 K at equilibrium and under applied pressure. Information about the main vibrational modes of sH hydrates and the factors that affect them such as guest type and pressure are revealed. The obtained IR spectra of sH gas hydrates agree with experimental/computational literature values. Hydrogen bond’s vibrational frequencies are used to determine the hydrate’s Young’s modulus which confirms the role of these bonds in defining sH hydrate’s elasticity. Vibrational frequencies depend on pressure and hydrate’s O···O interatomic distance. OH vibrational frequency shifts are related to the OH covalent bond length and present an indication of sH hydrate’s hydrogen bond strength. This work presents a new route to determine mechanical properties for sH hydrate based on IR spectra and contributes to the relatively small database of gas hydrates’ physical and vibrational properties.
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Klymenko, Vasyl, Vasyl Gutsul, Volodymyr Bondarenko, Viktor Martynenko, and Peter Stets. "Modeling of the Kinetics of the Gas Hydrates Formation on the Basis of a Stochastic Approach." Solid State Phenomena 291 (May 2019): 98–109. http://dx.doi.org/10.4028/www.scientific.net/ssp.291.98.
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Recently, more attention has been paid to the development of gas hydrate deposits, the use of gas-hydrated technologies, suitable for energy-efficient transportation of natural gas, the separation of gas mixtures, production and storage of cold, desalinating of seawater, etc. Hydrate formation is one of the main processes of gas-hydrate technological installations. In the article a model is proposed that describes the kinetics of the formation of hydrate in disperse systems, which are characteristic for real conditions of operation of gas-hydrate installations, on the basis of a stochastic approach using Markov chains. An example of numerical calculations is presented on the basis of the proposed model of the dynamics of the total mass of gas hydrates, and changes in the velocity of their formation and size distribution at different values of the nucleation constants and growth rate of the gas hydrates, and results of these calculations are analyzed. It is shown that the rate of formation of hydrate has a maximum value in half the time period of the whole process. The obtained results of the calculations of the dynamics the total mass of gas hydrates are in good agreement with the results of calculations by the equation of kinetics Kolmogorov-Avrami. The proposed model can be applied to the inverse problem: the determination of the nucleation constants and the rate of growth of gas hydrates by the results of the dynamics of the formation of hydrate and the changes in the fractional composition of the generated gas hydrates.
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Daghash, Shaden, Phillip Servio, and Alejandro Rey. "First-Principles Elastic and Anisotropic Characteristics of Structure-H Gas Hydrate under Pressure." Crystals 11, no. 5 (April 24, 2021): 477. http://dx.doi.org/10.3390/cryst11050477.
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Evaluating gas hydrates properties contributes valuably to their large-scale management and utilization in fundamental science and applications. Noteworthy, structure-H (sH) gas hydrate lacks a comprehensive characterization of its structural, mechanical, and anisotropic properties. Anisotropic and pressure dependent properties are crucial for gas hydrates’ detection and recovery studies. The objective of this work is the determination of pressure-dependent elastic constants and mechanical properties and the direction-dependent moduli of sH gas hydrates as a function of guest composition. First-principles DFT computations are used to evaluate the mechanical properties, anisotropy, and angular moduli of different sH gas hydrates under pressure. Some elastic constants and moduli increase more significantly with pressure than others. This introduces variations in sH gas hydrate’s incompressibility, elastic and shear resistance, and moduli anisotropy. Young’s modulus of sH gas hydrate is more anisotropic than its shear modulus. The anisotropy of sH gas hydrates is characterized using the unit cell elastic constants, anisotropy factors, and the angular dependent moduli. Structure-properties composition correlations are established as a function of pressure. It is found that compressing filled sH gas hydrates increases their moduli anisotropy. Differences in atomic bonding across a crystal’s planes can be expected in anisotropic structures. Taken together the DFT-based structure–properties–composition relations for sH gas hydrates provide novel and significant material physics results for technological applications.
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Pedchenko, Mykhailo, Larysa Pedchenko, Tetiana Nesterenko, and Artur Dyczko. "Technological Solutions for the Realization of NGH-Technology for Gas Transportation and Storage in Gas Hydrate Form." Solid State Phenomena 277 (June 2018): 123–36. http://dx.doi.org/10.4028/www.scientific.net/ssp.277.123.
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The technology of transportation and storage of gas in a gas-hydrated form under atmospheric pressure and slight cooling – the maximum cooled gas-hydrated blocks of a large size covered with a layer of ice are offered. Large blocks form from pre-cooled mixture of crushed and the granulated mass of gas hydrate. The technology of forced preservation gas hydrates with ice layer under atmospheric pressure has developed to increase it stability. The dependence in dimensionless magnitudes, which describes the correlation-regressive relationship between the temperature of the surface and the center gas hydrate block under its forced preservation, had proposed to facilitate the use of research results. Technology preservation of gas hydrate blocks with the ice layer under atmospheric pressure (at the expense of the gas hydrates energy) has designed to improve their stability. Gas hydrated blocks, thus formed, can are stored and transported during a long time in converted vehicles without further cooling. The high stability of gas hydrate blocks allows to distributed in time (and geographically) the most energy expenditure operations – production and dissociation of gas hydrate. The proposed technical and technological solutions significantly reduce the level of energy and capital costs and, as a result, increase the competitiveness of the stages NGH technology (production, transportation, storage, regasification).
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Li, Yaobin, Xin Xin, Tianfu Xu, Yingqi Zang, Zimeng Yu, Huixing Zhu, and Yilong Yuan. "Production Behavior of Hydrate-Bearing Sediments with Mixed Fracture- and Pore-Filling Hydrates." Journal of Marine Science and Engineering 11, no. 7 (June 29, 2023): 1321. http://dx.doi.org/10.3390/jmse11071321.
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Most hydrate-bearing sediments worldwide exhibit mixed pore- and fracture-filling hydrates. Due to the high exploitation value, pore-filling hydrate production is the focus of current hydrate production research, and there is a lack of systematic research on the decomposition of fracture-filling hydrates and their effects on the evolution of temperature and pressure in hydrate-bearing sediments. If only the decomposition characteristics of pore-filling hydrates are studied while the fracture-filling hydrates decomposition and its effects on the hydrate-bearing sediments production process are ignored, the obtained research results would be inconsistent with the actual situation. Therefore, in this study, the effects of fracture-filling hydrates with different dipping angles on the hydrate production process were studied, and the necessity of considering the phenomenon of mixed pore- and fracture-filling hydrates in hydrate-bearing sediments was illustrated. On this basis, the simulation of a typical site (GMGS2-16) with mixed pore- and fracture-filling hydrates was constructed, and the production process was researched and optimized. The results indicated that: (a) fracture-filling hydrates formed in shallow fine-grained sediments and gradually approached the area of pore-filling hydrates, before a stable mixed zone was formed; (b) the occurrence of fracture-filling hydrates was conducive to the hydrate-bearing sediment depressurization production, and the promoting effect of the fracture-filling hydrate with smaller dipping angles was stronger; and (c) depressurization combined with heat injection could effectively compensate for the local low temperature and secondary hydrate caused by the mass decomposition of fracture-filled hydrates.
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Braun, Doris, and Ulrich Griesser. "Insights into hydrate formation and stability of morphinanes." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C991. http://dx.doi.org/10.1107/s2053273314090081.
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The formation of multi-component crystals with water (hydrates) is a widespread phenomenon among organic molecules. Hydrate formation is of high practical relevance for industrially used materials, as it affects their physicochemical properties. [1,2] To exclude water or moisture in industrial processes is often difficult. Therefore knowledge about the existence and stability of hydrates and the understanding and control of the anhydrate/hydrate balance is mandatory for avoiding manufacturing problems. In order to improve our understanding of hydrate formation we selected representative substances (morphine, codeine, ethylmorphine) from a class of molecules (morphinanes), which are prone to crystallize along with water. Stable hydrates of both, free bases and HCl salts, have been observed in this important class of drug compounds. This allowed us to investigate the influence of different functional groups, the role of water and the Cl– counterion on the structure and properties of these morphinanes. A crystallization screen on the six compounds considerably extended the total number of known solid forms from twelve [3] to 17 and the number of crystal structures from five to twelve. Anhydrous polymorphs were detected for all compounds except ethylmorphine (one anhydrate) and its HCl salt (no anhydrate). The relative stabilities of the hydrated and anhydrous forms differ considerably, which was evaluated by moisture sorption studies and thermal analytical experiments. Two different hydrates, a tri- and dihydrate, were found for morphine HCl. In the free bases, the substituents define the number of hydrogen bond donor groups and lead to differences in the sterical hindrance around polar groups, influencing the intermolecular interactions, packing and stability. Hydrate formation results in higher dimensional hydrogen bond networks, whereas salt formation decreases the packing variability of the structures among the different compounds. Calorimetric measurements and lattice energy calculations were employed to estimate the heat of hydrate/anhydrate phase transformation, showing an enthalpic stabilization of the hydrates over the anhydrates. The combination of a variety of experimental techniques with computational modelling allowed us to generate sufficient kinetic, thermodynamic and structural information to understand the principles of hydrate formation of morphinanes.
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Sun, Jian Ye, Yu Guang Ye, Chang Ling Liu, and Jian Zhang. "Experimental Study on Gas Production from Methane Hydrate Bearing Sand by Depressurization." Applied Mechanics and Materials 310 (February 2013): 28–32. http://dx.doi.org/10.4028/www.scientific.net/amm.310.28.
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The simulate experiments of gas production from methane hydrates reservoirs was proceeded with an experimental apparatus. Especially, TDR technique was applied to represent the change of hydrate saturation in real time during gas hydrate formation and dissociation. In this paper, we discussed and explained material transformation during hydrate formation and dissociation. The hydrates form and grow on the top of the sediments where the sediments and gas connect firstly. During hydrates dissociation by depressurization, the temperatures and hydrate saturation presented variously in different locations of sediments, which shows that hydrates dissociate earlier on the surface and outer layer of the sediments than those of in inner. The regulation of hydrates dissociation is consistent with the law of decomposition kinetics. Furthermore, we investigated the depressurizing range influence on hydrate dissociation process.
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Kvamme, Bjørn, Jinzhou Zhao, Na Wei, and Navid Saeidi. "Hydrate—A Mysterious Phase or Just Misunderstood?" Energies 13, no. 4 (February 17, 2020): 880. http://dx.doi.org/10.3390/en13040880.
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Hydrates that form during transport of hydrocarbons containing free water, or water dissolved in hydrocarbons, are generally not in thermodynamic equilibrium and depend on the concentration of all components in all phases. Temperature and pressure are normally the only variables used in hydrate analysis, even though hydrates will dissolve by contact with pure water and water which is under saturated with hydrate formers. Mineral surfaces (for example rust) play dual roles as hydrate inhibitors and hydrate nucleation sites. What appears to be mysterious, and often random, is actually the effects of hydrate non-equilibrium and competing hydrate formation and dissociation phase transitions. There is a need to move forward towards a more complete non-equilibrium way to approach hydrates in industrial settings. Similar challenges are related to natural gas hydrates in sediments. Hydrates dissociates worldwide due to seawater that leaks into hydrate filled sediments. Many of the global resources of methane hydrate reside in a stationary situation of hydrate dissociation from incoming water and formation of new hydrate from incoming hydrate formers from below. Understanding the dynamic situation of a real hydrate reservoir is critical for understanding the distribution characteristics of hydrates in the sediments. This knowledge is also critical for designing efficient hydrate production strategies. In order to facilitate the needed analysis we propose the use of residual thermodynamics for all phases, including all hydrate phases, so as to be able to analyze real stability limits and needed heat supply for hydrate production.
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Horvat, Kristine, and Devinder Mahajan. "Carbon dioxide-induced liberation of methane from laboratory-formed methane hydrates." Canadian Journal of Chemistry 93, no. 9 (September 2015): 998–1006. http://dx.doi.org/10.1139/cjc-2014-0562.
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This paper reports a laboratory mimic study that focused on the extraction of methane (CH4) from hydrates coupled with sequestration of carbon dioxide (CO2) as hydrates, by taking advantage of preferential thermodynamic stability of hydrates of CO2 over CH4. Five hydrate formation-decomposition runs focused on CH4–CO2 exchange, two baselines and three with host sediments, were performed in a 200 mL high-pressure Jerguson cell fitted with two glass windows that allowed visualization of the time-resolved hydrate phenomenon. The baseline pure hydrates formed from artificial seawater (75 mL) under 6400–6600 kPa CH4 or 2800–3200 kPa CO2 (hydrate forming regime), when the bath temperature was maintained within 4–6 °C and the gas/liquid volumetric ratio was ∼1.7:1 in the water-excess systems. The data show that the induction time for hydrate appearance was largest at 96 h with CH4, while with CO2 the time shortened by a factor of four. However, when the secondary gas (CO2 or CH4) was injected into the system containing preformed hydrates, the entering gas formed the hydrate phase instantly (within minutes) and no lag was observed. In a system containing host Ottawa sand (104 g) and artificial seawater (38 mL), the induction period reduced to 24 h. In runs with multiple charges, the extent of hydrate formation reached 44% of the theoretical value in the water-excess system, whereas the value maximized at 23% in the gas-excess system. The CO2 hydrate formation in a system that already contained CH4 hydrates was facile and they remained stable, whereas CH4 hydrate formation in a system consisting of CO2 hydrates as hosts were initially stable, but CH4 gas in hydrates quickly exchanged with free CO2 gas to form more stable CO2 hydrates. In all five runs, even though the system was depressurized, left for over a week at room temperature, and flushed with nitrogen gas in between runs, hydrates exhibited the “memory effect”, irrespective of the gas used, a result in contradiction with that reported previously in the literature. The facile CH4–CO2 exchange observed under temperature and pressure conditions that mimic naturally occurring CH4 hydrates show promise to develop a commercial carbon sequestration system.
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Sai, Kateryna. "RESEARCH INTO PECULIARITIES OF PHASE TRANSITIONS DURING THE DISSOCIATION OF GAS HYDRATES." JOURNAL of Donetsk Mining Institute, no. 2 (2021): 51–59. http://dx.doi.org/10.31474/1999-981x-2021-2-51-59.
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Purpose. Analytical study of the dissociation process of gas hydrates taking into account the peculiarities of phase transitions occurring during their dissociation and described by the Clausius-Clapeyron equation. Methods. The research uses an integrated approach, which includes the analysis and generalization of literature sources devoted to studying the peculiarities and thermobaric properties of gas hydrates; processes of hydrate formation and accumulation; methods for the development of gas hydrate deposits and technologies for extracting the methane gas from them; analytical calculations of phase transitions of gas hydrates. Findings. The conditions for the formation of gas hydrate deposits have been analyzed and the peculiarities of stable existence of gas hydrates have been revealed. The existing experience in the development of gas hydrate technologies by leading scientists, world research laboratories, advanced design institutes and organizations is summarized. The mechanism of hydration formation in rocks is studied and some classifications of gas hydrate deposits occurring in sedimentary rock stratum are presented. It has been determined that gas hydrates in natural conditions usually occur not only in the form of pure hydrate reservoirs, but most often contain a certain share of rock intercalations, which makes the deposit structure heterogeneous. The mechanisms of hydrate formation and dissociation of gas hydrates have been revealed. It has been determined that the Clausius-Clapeyron equation in a modified form can be used to describe phase transitions both during the formation and dissociation of gas hydrates, taking into account the deposit heterogeneity. Originality. The Clausius-Clapeyron equation for the analysis of phase transformations in solid phases during hydrate formation and dissociation of gas hydrates is defined more exactly, taking into account the consumption of additional heat due to the influence of the properties of rock intercalations. Practical implications. The research results are useful for designing the rational thermobaric parameters (pressure and temperature) in the dissociation of natural or technogenic gas hydrates, as well as for optimal control of the kinetics of the process.
Dissertations / Theses on the topic "Hydrates"
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Nour, Sherif. "17-O NMR on Crystalline Hydrades Hydrates: Impact of Hydrogen Bonding." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32849.
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The water molecules in inorganic hydrate salts adopt different geometries and are involved in different hydrogen bond interactions. In this work, magic-angle spinning (MAS) and static 17O solid-state NMR experiments are performed to characterize the 17O electric field gradient (EFG) and chemical shift (CS) tensors of the water molecules in a series of inorganic salt hydrates which include: oxalic acid hydrate, barium chlorate hydrate, sodium perchlorate hydrate, lithium sulphate hydrate, and potassium oxalate hydrate, which were all enriched with 17O water. Data were acquired at magnetic field strengths of 9.4, 11.75, and 21.1 T. Gauge-including projector-augmented-wave density functional theory (GIPAW DFT) calculations are performed on barium chlorate hydrate and oxalic acid hydrate where structural changes including the Ow-H•••O distance, H-O-H angle, and O-H distance are employed to understand their impact on the NMR parameters. Furthermore, simplified molecular models consisting of a metal cation and a water molecule were built to establish the effect the M-Ow distance has on the parameters. The computational studies are then used to understand the experimental results. The 17O quadrupolar coupling constant ranged from 6.75 MHz in K2C2O4•H2O to 7.39 MHz in NaClO4•H2O while the asymmetry parameter ranged from 0.75 in NaClO4•H2O to 1.0 in K2C2O4•H2O and the isotropic chemical shift ranged from -15.0 ppm in NaClO4•H2O to 19.6 ppm in BaClO3•H2O. The computational results revealed the trends for each parameter, where there is an increasing trend for quadrupolar coupling constant and span as a function of increasing hydrogen bond distance, decreasing trend for the three chemical shift tensors as a function of increasing M-Ow distance and unclear trends for asymmetry parameter and skew due to competing electronic factors. Overall, this study provides benchmark 17O NMR data for water molecules in crystalline hydrates, including the first measurement of 17O chemical shift anisotropy for such materials.
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Alfvén, Linda, and Sorin Ignea. "Characterization of Gas hydrates." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-203043.
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Gas hydrates are naturally occurring crystalline formations consisting of crystal structural “cages” which make up cavities where gas molecules can be trapped. Hydrates are formed under specific pressure and temperature conditions in the ground, which limits their presence to permafrost and deep sea continental margins. The interest for gas hydrates has grown bigger in the past time, mainly because of the potential as a new energy source but also because of the possibility of carbon dioxide (CO2) storage and its potential linkage to different geological hazards. Gas hydrates are still relatively poorly understood with many questions to be answered. Therefore research in this area is important. In our study we have been focusing on characterization of gas hydrate structures and their gas composition. By using the two different analytical methods X-ray powder diffraction (XRD) and gas chromatography. For this study to be successfully carried out we needed access to equipment and expertise which is only to be found in few places on Earth. Our lab work was therefore done at Pontifica Universidade Catolica do Rio Grande do Sul in Porto Alegre Brazil where a research project in gas hydrates is on going. Because of the research projects secrecy we do not know where our gas hydrate samples come from which mean we cannot link our results to any geographic area. The structural analysis shows structure I hydrate which is characterized by the presence of small gas molecules such as hydrocarbons. The results from the gas content validated that it is structure I since large concentrations of methane gas (CH4) and sulphur gas (H2S) were detected. The presence of these gases implies that the formation conditions are in a marine environment at the sulphate-methane transition zone (SMTZ).
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Hughes, Thomas John. "Plug Formation and Dissociation of Mixed Gas Hydrates and Methane Semi-Clathrate Hydrate Stability." Thesis, University of Canterbury. Chemical and Process Engineering, 2008. http://hdl.handle.net/10092/1579.
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Gas hydrates are known to form plugs in pipelines. Hydrate plug dissociation times can be predicted using the CSMPlug program. At high methane mole fractions of a methane + ethane mixture the predictions agree with experiments for the relative dissociation times of structure I (sI) and structure II (sII) plugs. At intermediate methane mole fractions the predictions disagree with experiment. Enthalpies of dissociation were measured and predicted with the Clapeyron equation. The enthalpies of dissociation for the methane + ethane hydrates were found to vary significantly with pressure, the composition, and the structure of hydrate. The prediction and experimental would likely agree if this variation in the enthalpy of dissociation was taken in to account.
In doing the plug dissociation studies at high methane mole fraction a discontinuity was observed in the gas evolution rate and X-ray diffraction indicated the possibility of the presence of both sI and sII hydrate structures. A detailed analysis by step-wise modelling utilising the hydrate prediction package CSMGem showed that preferential enclathration could occur. This conclusion was supported by experiment.
Salts such as tetraisopentylammonium fluoride form semi-clathrate hydrates with melting points higher than 30 ℃ and vacant cavities that can store cages such as methane and hydrogen. The stability of this semi-clathrate hydrate with methane was studied and the dissociation phase boundary was found to be at temperatures of about (25 to 30) K higher than that of methane hydrate at the same pressure.
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Sadeq, Dhifaf Jaafar. "Gas Hydrates Investigation: Flow Assurance for Gas Production and Effects on Hydrate-bearing Sediments." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/75809.
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This thesis was aimed to study gas hydrates in terms of their equilibrium conditions in bulk and their effects on sedimentary rocks. The hydrate equilibrium measurements for different gas mixtures containing CH4, CO2 and N2 were determined experimentally using the PVT sapphire cell equipment. We imaged CO2 hydrate distribution in sandstone, and investigated the hydrate morphology and cluster characteristics via μCT. Moreover, the effect of hydrate formation on the P-wave velocities of sandstone was investigated experimentally.
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Rojas, González Yenny V. "Tetrahydrofuran and natural gas hydrates formation in the presence of various inhibitors." Thesis, Curtin University, 2011. http://hdl.handle.net/20.500.11937/2332.
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The aim of this thesis is to investigate the formation process of tetrahydrofuran (THF) hydrates and natural gas hydrates, and the effect of kinetic hydrate inhibitors (KHIs) on the formation and growth of these hydrates. Kinetic experiments were conducted in pressure cells in the presence of, or without, KHIs. Interfacial and electrokinetic techniques, including surface tension, Langmuir monolayers and zeta potential, were used to study the adsorption preferences of the inhibitors in two different interfaces, air–liquid and hydrate–liquid. For comparison purposes, selected thermodynamic hydrate inhibitors (THIs) and antiagglomerators (AAs) were investigated in some of the experiments. Sodium chloride was used in experiments where suitable.Four well known KHI polymers, including a terpolymer of N-vinylpyrrolidone, Nvinylcaprolactam and dimethylamino-ethylmethacrylate (Gaffix VC713), poly(Nvinylcaprolactam) (Luvicap EG), and poly(N-vinylpyrrolidone) (PVP40, Mn=40k and PVP360, Mn=360k), were selected for the investigation. A copolymer containing both poly(ethylene oxide) and vinylcaprolactam segments (PEO-VCap) that was developed in the Polymer Research lab in Curtin University, was also investigated. Other chemicals, including methanol (MeOH) and monoethylene glycol (MEG) were used as THIs. Sodium dodecyl sulphate (SDS) was used as an AA.During the THF hydrates kinetic studies, several experimental parameters that are associated with the nucleation and crystal growth process were investigated. The onset of THF hydrates formation, the maximum temperature spike, the magnitude of the temperature rise associated with the hydrate formation, the rate of hydrate formation, and the temperature at the end-point of the hydrate formation, were reported to compare inhibition efficiency. Subcooling was used as the driving force for hydrates formation. The experimental results show that the kinetics of the THF hydrate is affected by the physical chemical environment, which includes the concentration and types of additives used for the inhibition of the hydrates. In comparison to the system containing no inhibitor, there was an increase in subcooling and a reduced onset temperature of hydrates formation when various inhibitors were used.Surface tension studies have demonstrated that the adsorption of KHIs molecules at the air–liquid interface is directly related to its effectiveness inhibiting hydrates. The differences in the fundamental properties of the polymer molecules, such as molecular weight and flexibility of the polymer chain, have an impact on the different adsorption behaviours at the air–liquid interface for all of them. The inhibition efficiency of KHIs was enhanced in the presence of NaCl 3.5 wt% for all the inhibitors, and seemed to be associated to maximum packing of polymer molecules in the monolayer and low surface tension values. The zeta potential results, measured at the THF hydrate–liquid interface, have shown some correspondence with the surface tension results at the air liquid–interface. The compound, with a higher adsorption at the air liquid–interface also showed a higher adsorption at the surface of the THF hydrate. It was observed, that the inhibitor showing the higher adsorption on zeta potential measurements was more effective for reducing the onset temperature of hydrates formation.The kinetic studies have been extended to structure II natural gas hydrates systems, to examine whether the hypothesis proposed for THF hydrates systems were applicable to the gas hydrate systems. Gaffix VC713, Luvicap EG, PVP40 and PEO-VCap were used in this investigation. The gas hydrate formation rate was always slower when KHIs were present in the liquid phase. In all cases, the presence of KHI decreases the temperature of the onset hydrate formation. Polymers, such as PVP40 and PEO-VCap, that showed the worse and the best inhibition performances respectively in THF crystals, exhibited the opposite inhibition performance in gas hydrate crystals. This suggests that a different mechanism of KHIs surface adsorption could be operating on different hydrates surfaces.Overall, the investigation of the kinetics of formation and inhibition on THF hydrates and natural gas hydrates in the presence of KHIs, indicate that the gas hydrate formation rate during gas hydrate formation, is always slower when KHIs are present in the liquid phase. The inhibition mechanism of KHIs in the THF hydrates systems may differ significantly from that of the gas hydrate systems. Adsorption studies, demonstrate that the adsorption of KHIs are directly related to their effectiveness inhibiting hydrates. Surface tension and zeta potential approaches provide valuable information for understanding hydrates formation and inhibition mechanisms.
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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.
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Les hydrates de méthane (MHs), composés de gaz de méthane et d’eau, se forment naturellement à haute pression et faible température dans les sédiments marins ou pergélisols. Ils sont actuellement considérés comme une ressource énergétique (principalement MHs dans les sédiments sableux) mais aussi une source de géo-hasards et du changement climatique (MHs dans les sédiments grossiers et fins). La connaissance de leurs propriétés mécaniques/physiques, qui changent considérablement avec la morphologie et distribution des hydrates dans les pores, est très importante pour minimiser les impacts environnementaux liés aux futures exploitations du gaz de méthane à partir des sédiments sableux contenant des MHs (MHBS). La plupart des études expérimentales concernent MHBS synthétiques à cause des difficultés pour récupérer des échantillons intacts. Différentes méthodes ont été proposées pour former MHs dans les sédiments au laboratoire pour reconstituer des sédiments naturels, mais sans grand succès. Cette thèse a pour objectif d’évaluer la morphologie, la distribution des MHs dans les MHBS synthétiques à différentes échelles et d’étudier les effets des MHs (leur morphologie et teneur en hydrate) sur les propriétés mécaniques des MHBS. Deux méthodes de formation d’hydrates dans les sédiments sableux ont été proposées. Au niveau macroscopique, la distribution des hydrates au niveau des pores est évaluée en se basant sur la vitesse de propagation d’onde de compression (mesurée et calculée à partir des modèles existants). Des essais triaxiaux ont été utilisés pour étudier l’influence des MHs à différentes teneurs en hydrate sur les propriétés mécaniques des MHBS. Par ailleurs, l’Imagerie par Résonance Magnétique a été utilisée pour étudier la cinétique de formation/dissociation d’hydrates et aussi la distribution des hydrates sur l’ensemble de l’échantillon. Les résultats montrent qu’un cycle de température en conditions non drainées complète la redistribution des hydrates dans les pores après la saturation en eau de l’échantillon à haute teneur en hydrate. La distribution des hydrates sur l’ensemble de l’échantillon devient plus homogène avec la saturation en eau suivie par un cycle de température. En outre, les propriétés mécaniques des sédiments augmentent avec l’augmentation de la teneur en hydrate.A l’échelle du grain, la tomographie aux rayons X (XRCT) et celle au Synchrotron XRCT (SXRCT, Synchrotron SOLEIL) ont été utilisées pour observer la morphologie et la distribution des MHs au niveau des pores des sédiments sableux. Ce travail n’a pas été facile car il nécessitait des dispositifs expérimentaux compliqués (pour maintenir la haute pression et faible température) mais aussi en raison du faible contraste entre MHs et l’eau sur les images de XRCT, SXRCT. Des dispositifs spécifiques ont été développés pour étudier la formation d’hydrates, la morphologie et la distribution à l’échelle du grain des MHs en utilisant XRCT, SXRCT. De plus, une nouvelle méthode a été développée pour déterminer plus précisément les fractions volumiques d’un milieu triphasé à partir des images XRCT. Des observations au Microscope Optique (en coopération avec l’Université de Pau) ont également été faites pour confirmer diverses morphologies de MHs dans les sédiments sableux. Les morphologies et distributions d’hydrates observées sont comparées avec les modèles existants. Les observations montrent que la formation des MHs dans les sédiments sableux est un processus instable et compliqué. Différentes morphologies et distributions au niveau des pores des MHs peuvent coexister. Il parait indispensable de tenir compte des vraies morphologies et distributions au niveau des pores des MHs pour les études numériques utilisant des modèles simplifiés.Mots-clés: hydrate de méthane, sédiments sableux, formation, dissociation, morphologies, distribution, propriétés mécaniques, XRCT, SXRCT, microscope optique, essais triaxiaux, modèle de mécanique des rochesMethane 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
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Jang, Jaewon. "Gas production from hydrate-bearing sediments." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41145.
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Gas hydrates are crystalline compounds made of gas and water molecules. Methane hydrates are found in marine sediments and permafrost regions; extensive amounts of methane are trapped in the form of hydrates. The unique behavior of hydrate-bearing sediments requires the development of special research tools, including new numerical algorithms (tube- and pore-network models) and experimental devices (high pressure chambers and micromodels). Hydraulic conductivity decreases with increasing variance in pore size distribution; while spatial correlation in pore size reduces this trend, both variability and spatial correlation promote flow focusing. Invading gas forms a percolating path while nucleating gas forms isolated gas bubbles; as a result, relative gas conductivity is lower for gas nucleation than for gas invasion processes, and constitutive models must be properly adapted for reservoir simulations. Physical properties such as gas solubility, salinity, pore size, and mixed gas conditions affect hydrate formation and dissociation; implications include oscillatory transient hydrate formation, dissolution within the hydrate stability field, initial hydrate lens formation, and phase boundary changes in real field situations. High initial hydrate saturation and high depressurization favor gas recovery efficiency during gas production from hydrate-bearing sediments. Even a small fraction of fines in otherwise clean sand sediments can cause fines migration and concentration, vuggy structure formation, and gas-driven fracture formation during gas production by depressurization.
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Zugic, Minjas. "Raman spectra of clathrate hydrates." Thesis, King's College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271176.
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Barboux, Philippe. "Conductivite protonique dans les hydrates." Paris 6, 1987. http://www.theses.fr/1987PA066034.
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Barboux, Philippe. "Conductivité protonique dans les hydrates." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37602594d.
Full textBooks on the topic "Hydrates"
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Giavarini, Carlo, and Keith Hester. Gas Hydrates. London: Springer London, 2011. http://dx.doi.org/10.1007/978-0-85729-956-7.
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Ruffine, Livio, Daniel Broseta, and Arnaud Desmedt, eds. Gas Hydrates 2. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2018. http://dx.doi.org/10.1002/9781119451174.
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Ye, Yuguang, and Changling Liu, eds. Natural Gas Hydrates. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-31101-7.
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Broseta, Daniel, Livio Ruffine, and Arnaud Desmedt, eds. Gas Hydrates 1. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2017. http://dx.doi.org/10.1002/9781119332688.
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Maeda, Nobuo. Nucleation of Gas Hydrates. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51874-5.
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Rajput, Sanjeev, and Naresh Kumar Thakur. Exploration of Gas Hydrates. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-14234-5.
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Lal, Bhajan, and Omar Nashed. Chemical Additives for Gas Hydrates. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-30750-9.
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Kvenvolden, Keith A. Gas hydrates in oceanic sediment. Denver, Colo: Dept. of the Interior, U.S. Geological Survey, 1988.
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Sloan, E. Dendy. Clathrate hydrates of natural gases. 3rd ed. Boca Raton, FL: CRC Press/Taylor & Francis, 2007.
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Riedel, Michael. Geophysical characterization of gas hydrates. Tulsa, OK: Society of Exploration Geophysicists, 2010.
Find full textBook chapters on the topic "Hydrates"
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Luo, Min, and Yuncheng Cao. "Gas Hydrates at Seeps." In South China Sea Seeps, 55–67. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1494-4_4.
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AbstractGas hydrates have been the focus of intensive research during recent decades due to the recognition of their high relevance to future fossil energy, submarine geohazards, and global carbon and climate changes. Cold seep-related gas hydrate systems have been found in both passive and active margins worldwide. A wealth of data, including seismic imaging, borehole logging, seafloor surveys, and coring, suggest that seep-related gas hydrates are present in the western Taixinan Basin and the Qiongdongnan Basin of the northern South China Sea (SCS). Here, we provide an overview of the current understanding of seep-related gas hydrate systems in the northern SCS and underscore the need for more systematic work to uncover the factors governing the interplay of hydrate dynamics and gas seepage and to quantitatively assess the temporal and spatial variability of gas hydrate and cold seep systems.
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Gupta, Harsh K., and Kalachand Sain. "Gas-Hydrates." In Encyclopedia of Natural Hazards, 377–78. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-1-4020-4399-4_151.
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Kumar, Rajnish, and Praveen Linga. "Gas Hydrates." In Encyclopedia of Earth Sciences Series, 1–7. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-39193-9_177-1.
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Kumar, Rajnish, and Praveen Linga. "Gas Hydrates." In Encyclopedia of Earth Sciences Series, 535–41. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-39312-4_177.
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Thakur, Naresh Kumar, and Sanjeev Rajput. "Gas Hydrates." In Exploration of Gas Hydrates, 49–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14234-5_3.
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Shariati, Alireza, Sona Raeissi, and Cor J. Peters. "Clathrate Hydrates." In Handbook of Hydrogen Storage, 63–79. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527629800.ch3.
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Maeda, Nobuo. "Gas Hydrates." In Nucleation of Gas Hydrates, 61–81. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51874-5_3.
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Pedersen, Karen Schou, Peter Lindskou Christensen, and Jawad Azeem Shaikh. "Gas Hydrates." In Phase Behavior of Petroleum Reservoir Fluids, 362–86. 3rd ed. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9780429457418-13.
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Giavarini, Carlo, and Keith Hester. "The Evolution of Energy Sources." In Gas Hydrates, 1–11. London: Springer London, 2011. http://dx.doi.org/10.1007/978-0-85729-956-7_1.
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Giavarini, Carlo, and Keith Hester. "Environmental Issues with Gas Hydrates." In Gas Hydrates, 159–72. London: Springer London, 2011. http://dx.doi.org/10.1007/978-0-85729-956-7_10.
Full textConference papers on the topic "Hydrates"
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"Thermal stability of CO2 hydrates in porous media with varying grain size in brine solution." In Sustainable Processes and Clean Energy Transition. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902516-13.
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Abstract. In the present work, the heat transfer behavior of CO2 hydrate dissociation was studied in three quartz sand particles (QS-1, QS-2 and QS-3) with varying grain sizes. The heat transfer behavior was evaluated by determining the heating rates of the porous media (quartz sand) during the CO2 hydrate dissociation process in 3.3 wt.% NaCl. The experiment was performed using sandstone hydrate reactor by first forming the CO2 hydrates at 4 MPa and 274.15 K and then dissociating the hydrates from 274.15 to 277.15 K, respectively. The results indicate that the thermal response of the porous sediment was significantly influenced by the hydrates as well as the porous sediment properties. The heating rate of the porous media increased when the grain size increased. However, the presence of CO2 hydrates reduced the heat transfer behavior of the porous sediment due to the endothermic nature of hydrate dissociation. The heating behavior of the porous media with hydrates mainly depends on the type and pattern of hydrate formed (pore-filling, load-bearing, and cementation) and the location of the hydrates within the pores of the porous sediment. The pore-filling type of hydrate formation in porous sediments provides high thermal stability for CO2 hydrate storage due to its less contact with the quartz sand particles. However, the pore-filling hydrate formation type is challenged with low or undesired CO2 hydrate storage capacity. These findings will provide meaningful insights to select favorable sediment properties/sites for CO2 storage in the hydrate form in porous sediments.
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Yang, J., and Y. Wang. "Experimental Study on Formation and Decomposition Characteristics of Tetrahydrofuran and Methane Hydrate Based on Microfluidic Chip Technology." In Innovative Geotechnologies for Energy Transition. Society for Underwater Technology, 2023. http://dx.doi.org/10.3723/zjsz8344.
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Gas hydrates are considered a promising energy source for the 21st century, and understanding their formation and decomposition processes is crucial. This study utilized micro-fluidic technology to observe the secondary formation and decomposition of hydrates at the pore scale, comparing methane-tetrahydrofuran(THF)-water and methane-water systems. The study found that hydrates tended to form and decompose at the gas-liquid interface, and the second formation rate of hydrates was higher than the first. During depressurization, hydrates located at the solid-liquid interface decomposed first, followed by decomposition towards the interior of the hydrate. The study sheds light on the formation and decomposition characteristics of gas hydrates at the pore scale, providing some insights for the safe and efficient exploitation of gas hydrate.
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Schulz, Anne, and Heike Strauß. "Ethylene Glycol as Gas Hydrate Stabilising Substance." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41264.
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Gas hydrates are solid substances consisting of water and gas which are stable under high pressure and low temperature conditions. After Davy discovered chlorine hydrate in 1810, gas hydrates from natural gas were found to be the reason for gas pipeline plugging in 1934 by Hammerschmidt. In 1965, the Russian scientist Makogon discovered natural gas hydrate deposits. This was the beginning of research in the geological occurrence of the gas hydrates. Today, hundreds of gas hydrate wells for exploration have been drilled all over the world in the permafrost and deep sea regions. Several big projects for gas hydrate research and exploration have been financed by Japan, India, Korea, China and the USA. It is assumed that the amount of carbon in natural gas hydrates is twice the amount present in oil, gas and coal together. This makes them interesting as a future energy source. To drill into horizontal layers filled with gas hydrates in the pores, directional wells are needed. To achieve an adequate cutting transport, a high performance drilling fluid has to be used instead of sea water. The drilling fluid must be able to keep the gas hydrate reservoir stable while drilling and prevent the formation of secondary gas hydrates in the liquid. Moreover, the gas hydrate cuttings should not dissociate on their way to the surface. To avoid altering of the drilling fluid due to water and gas produced as a result of gas hydrate dissociation, cuttings should be kept stable to separate them from the fluid like any other rock cuttings by the surface equipment. To prevent gas hydrate formation, thermodynamic inhibitors, like salt, glycols or methanol are used. Also, kinetic inhibitors are added to the drilling fluid to prevent gas hydrate agglomeration and formation for a period of time. Well known kinetic inhibitors are polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and polyvinylcaprolactam (PVCap). Although ethylene glycol (EG) is seen as a thermodynamic inhibitor for gas hydrates, it is shown in this study that it is able to stabilize methane hydrate significantly. For the investigation, a high pressure cell with pressures up to 8.5 MPa was used. The equilibrium point of methane hydrate was detected. Solutions with PVP, PEG, hydroxyethylcellulose (HEC), Sodium dodecyl sulfate (SDS) and a kinetic inhibitor containing EG were tested (concentrations from 1 to 10 wt.‰). PVP, PEG and HEC could not stabilize gas hydrates at the test condition. SDS showed both a stabilizing and promoting effect. EG can significantly stabilize gas hydrates.
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Kar, Aritra, Palash Acharya, Awan Bhati, Arjang Shahriari, Ashish Mhahdeshwar, Timothy A. Barckholtz, and 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.
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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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Rabbani, Harris Sajjad, Muhammad Saad Khan, M. Fahed Aziz Qureshi, Mohammad Azizur Rahman, Thomas Seers, and Bhajan Lal. "Analytical Modelling of Gas Hydrates in Porous Media." In Offshore Technology Conference Asia. OTC, 2022. http://dx.doi.org/10.4043/31645-ms.
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Abstract A mathematical model is presented to predict the formation of gas hydrates in porous media under various boundary conditions. The new mathematical modeling framework is based on coupling the analytical pore network approach (APNA) and equation proposed by De La Fuente et al. [1]. Further, we also integrate thermodynamic models to capture the phase boundary at which the formation of gas hydrates takes place. The proposed analytical framework is a set of equations that are computationally inexpensive to solve, allowing us to predict the formation of gas hydrates in complex porous media. Complete governing equations are provided, and the method is described in detail to permit readers to replicate all results. To demonstrate the formation of hydrates in porous media, we analyzed the saturation of hydrates in porous media with different properties. Our model shows that the hydrate formation rate is positively related to the porous media's pore size. The hydrates were found to be preferably formed in the porous media composed of relatively larger pores, which could be attributed to the weak capillary forces resisting the formation of hydrates in porous media. The novelty of the new analytical model is the ability to predict the gas hydrates formation in porous media in a reasonable time using standard engineering computers. Furthermore, the model can aid in the estimation of natural gas hydrate reservoirs, which offer the avenue for effective methane recovery from the vast natural gas hydrate reserves in continental margins.
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Indina, V., B. R. B. Fernandes, M. Delshad, R. Farajzadeh, and K. Sepehrnoori. "On the Significance of Hydrate Formation/Dissociation during CO2 Injection in Depleted Gas Reservoirs." In SPE Conference at Oman Petroleum & Energy Show. SPE, 2024. http://dx.doi.org/10.2118/218550-ms.
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Abstract The study aims to quantitatively assess the risk of hydrate formation within the porous formation and its consequences to injectivity during storage of CO2 in depleted gas reservoirs considering low temperatures caused by the Joule Thomson (JT) effect and hydrate kinetics. The aim was to understand which mechanisms can mitigate or prevent the formation of hydrates. The key mechanisms we studied included water dry-out, heat exchange with surrounding rock formation, and capillary pressure. A compositional thermal reservoir simulator is used to model the fluid and heat flow of CO2 through a reservoir initially composed of brine and methane. The simulator can model the formation and dissociation of both methane and CO2 hydrates using kinetic reactions. This approach has the advantage of computing the amount of hydrate deposited and estimating its effects on the porosity and permeability alteration. Sensitivity analyses are also carried out to investigate the impact of different parameters and mechanisms on the deposition of hydrates and the injectivity of CO2. Simulation results for a simplified model were verified with results from the literature. The key results of this work are: (1) The Joule-Thomson effect strongly depends on the reservoir permeability and initial pressure and could lead to the formation of hydrates within the porous media even when the injected CO2 temperature was higher than the hydrate equilibrium temperature, (2) The heat gain from underburden and overburden rock formations could prevent hydrates formed at late time, (3) Permeability reduction increased the formation of hydrates due to an increased JT cooling, and (4) Water dry-out near the wellbore did not prevent hydrate formation. Finally, the role of capillary pressure was quite complex, where it reduced the formation of hydrates in certain cases and increased in other cases. Simulating this process with heat flow and hydrate reactions was also shown to present severe numerical issues. It was critical to select convergence criteria and linear system tolerances to avoid large material balance and numerical errors.
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Chen, Yuchuan, Bohui Shi, Wenping Lan, Fangfei Huang, Shunkang Fu, Haiyuan Yao, and Jing Gong. "Study on Hydrate Formation and Dissociation in the Presence of Fine-Grain Sand." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93200.
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Abstract During the solid fluidization exploitation of shallow non-diagenetic NGHs (Natural Gas Hydrates) in the deep-water, hydrates together with mineral sand, natural gas, seawater and drilling fluids flow in the production pipeline. Natural gas released from hydrates during the process of solid fluidization will reform hydrates under the suitable conditions. Therefore, research on the formation and dissociation of methane hydrates in the presence of fine-grain sands is of great significance for ensuring the flow assurance of solid fluidization exploitation of shallow non-diagenetic NGHs in the deep-water field. In this paper, a high-pressure autoclave was used to carry out the experiments of hydrate formation and dissociation under different initial pressures and particle sizes of the fine-grain sand, for investigating into the hydrate induction time, formation amount, rate and dissociation affected by the presence of the fine-grain sand. Results indicated that hydrate formation kinetics in the presence of fine-grain sand was supposed to be also affected by mass/heat transfer, thermodynamics and kinetics. The fine-grain sand would be dispersed in the water phase under the effect of buoyancy, gravity and shearing force. Besides, the fine-grain sand at the gas-water interface would hinder the mass transfer of the methane gas into the water, inhibiting the nucleation of the hydrates, which was more obviously at the lower pressure. When the driving force for hydrate formation was larger, hydrate formation amount increased with the decrease of the particle size of the fine-grain sand. However, hydrate formation amount decreased with the decrease of the particle size of the fine-grain sand when the driving force for hydrate formation was lower. The average growth rate in the presence of fine-grain sand with 2.9 μm was larger than that of 9.9 μm. However, hydrates grew rapidly and subsequently tended to grow at a lower rate in the presence of fine-grain sand with 2.9 μm at 8.0 MPa initial pressure, which was assumed to be affected by the unconverted water wrapped inside the hydrate shell. The changing trends of gas emission during the dissociation process between the sand-containing system and the pure water system were nearly the same. The amount of gas emission reached a peak value within 15 minutes and then tended to stabilize. The difference in the amount of gas emission mainly depended on the formation amount before hydrate dissociation. Hydrates grew rapidly once methane hydrates nucleated in the presence of the fine-grain sand at the lower pressure, which would increase the plugging risk during the process of the solid fluidization exploitation. Further study of the fine-grain sand on flow assurance during hydrate dissociation process should be done in the future. The results of this paper provided an important theoretical basis and technical support for reducing the risk in the process of the solid fluidization exploitation of shallow non-diagenetic NGHs in the deep-water field.
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Delgado-Linares, Jose G., Ahmad A. A. Majid, Luis E. Zerpa, and 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.
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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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Nishimoto, Hiroyuki, Masahiro Ota, Hajime Endou, Kazuhiko Murakami, and Daisuke Hoshino. "Clathrate-Hydrate Production From Methane, Xenon, CO2, Helium Gases and Their Mixed Gases." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41365.
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In the present study, the production characteristics of the hydrates from methane, xenon and their mixed gases and the application of a hydrate production technology for the separation of mixed gases such as CO2 and helium gases are discussed. Methane, xenon and CO2 can form hydrates. On the other hand, helium can’t produce the hydrate. Therefore, by using the hydrate production technology, CO2 could be separated from the mixed gases of CO2 and helium as the CO2 hydrate. In the present paper an autoclave experiment apparatus is used for the production of the hydrate.
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Liu, Ni, Xinping Ouyang, Ju Li, and Daoping Liu. "Heat Transfer During Gas Hydrate Film Formation on Gas-Liquid Interface." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22990.
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Gas hydrates are solid, crystalline, ice-like compounds composed of water and guest molecules. The formation of gas hydrates is a complex process with heat and mass transfer in gas, liquid and solid. Increasing the hydrates formation rate and the storage capacity, reducing hydrate induction time are main technical barriers for the application of gas hydrate. A one-dimensional numerical model of heat transfer during gas hydrate film formation on gas-liquid interface is investigated by analyzing the process of static system. According to the rate of gas consumed, the relation between the thickness of hydrate film and time can be obtained. The temperature distribution of different phase in the system is analyzed and the effect of temperature distribution of water is confirmed. The result indicates that it is effective to accelerate the rate of hydrate formation by enhancing the heat transfer in water phase.
Reports on the topic "Hydrates"
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Malone, R. Gas hydrates. Office of Scientific and Technical Information (OSTI), April 1990. http://dx.doi.org/10.2172/6129491.
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Smith, S. L. Natural gas hydrates. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2001. http://dx.doi.org/10.4095/212230.
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Seol, Yongkoo, and George Guthrie. Hydrates Annual FY13 Format. Office of Scientific and Technical Information (OSTI), April 2014. http://dx.doi.org/10.2172/1128555.
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R.E. Rogers. NATURAL GAS HYDRATES STORAGE PROJECT. Office of Scientific and Technical Information (OSTI), June 1999. http://dx.doi.org/10.2172/760130.
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Basques, Eric O. NETL/MHEP - Methane Hydrates Fellowship Program. Office of Scientific and Technical Information (OSTI), May 2018. http://dx.doi.org/10.2172/1439058.
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