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1
Dmytrenko, Victoriia, Oleksandr Lukin, and 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, no. 1(65) (2022): 39–43. http://dx.doi.org/10.15587/2706-5448.2022.261716.
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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.
2
Victoriia, Dmytrenko, Lukin Oleksandr, and Savyk Vasyl. "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, no. 1(65) (2022): 39–43. https://doi.org/10.15587/2706-5448.2022.261716.
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<em>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.</em> <em>At the same time, they contain enormous natural gas resources.</em> <em>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.</em> <em>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.</em> <em>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.</em> <em>It is shown that morphological differences in the macro- or microstructure of artificially formed gas hydrate samples can affect the results of research.</em> <em>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.</em>
3
Ge, Yongqiang, Chen Cao, Jiawang Chen, et al. "Monitoring and Research on Submarine Hydrate Mound: Review and Future Perspective." Marine Technology Society Journal 56, no. 4 (2022): 140–62. http://dx.doi.org/10.4031/mtsj.56.4.14.
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Abstract Submarine hydrate mounds are important indicators of submarine methane seepages, hydrocarbon reservoirs, and seabed instability. In order to fully understand the formation of hydrate mounds, here, we review the study of hydrate mounds, in which the morphology, the formation mechanism, as well as the research techniques are introduced. The formation mechanism of hydrate mounds can be classified into: (1) The sediment volume expands due to the formation and accumulation of shallow hydrates; (2) unconsolidated shallow sediment layers respond mechanically to increasing pore pressure caused by shallow gas accumulation; (3) materials extrude from submarine layers driven by the over-pressure caused by shallow gas accumulation; and (4) the interaction of multiple factors. Most hydrate mounds occur in submarine gas hydrate occurrence areas. Active hydrate mounds are circular or ellipse well-rounded shaped, with gas seepages and abundant organisms, whereas inactive hydrate mounds are rough or uneven irregular shaped, with low flux of fluid in the migration channel. Due to the limitation of long-term in-situ observation technology, the existing observation method makes it possible to provide basic morphology features, stratigraphic structures, and fluid migration channels of the hydrate mound. Future research should be focused on the long-term in-situ monitoring technology, the formation mechanism of the hydrate mounds, and the role of gas hydrates in the seafloor evolution. In addition, the features of hydrate mounds (e.g., gas chimneys and fluid migration conduits) and the relationship between hydrate mounds and pockmarks could be further studied to clarify the influence of methane release from hydrate mounds on biogeochemical processes and the atmospheric carbon contents.
4
Pan, Mengdi, Nur Aminatulmimi Ismail, Manja Luzi-Helbing, Carolyn A. Koh, and Judith M. Schicks. "New Insights on a µm-Scale into the Transformation Process of CH4 Hydrates to CO2-Rich Mixed Hydrates." Energies 13, no. 22 (2020): 5908. http://dx.doi.org/10.3390/en13225908.
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The global occurrences of natural gas hydrates lead to the conclusion that tremendous amounts of hydrocarbons are bonded in these hydrate-bearing sediments, serving as a potential energy resource. For the release of the hydrate-bonded CH4 from these reservoirs, different production methods have been developed during the last decades. Among them, the chemical stimulation via injection of CO2 is considered as carbon neutral on the basis of the assumption that the hydrate-bonded CH4 is replaced by CO2. For the investigation of the replacement process of hydrate-bonded CH4 with CO2 on a µm-scale, we performed time-resolved in situ Raman spectroscopic measurements combined with microscopic observations, exposing the CH4 hydrates to a CO2 gas phase at 3.2 MPa and 274 K. Single-point Raman measurements, line scans and Raman maps were taken from the hydrate phase. Measurements were performed continuously at defined depths from the surface into the core of several hydrate crystals. Additionally, the changes in composition in the gas phase were recorded. The results clearly indicated the incorporation of CO2 into the hydrate phase with a concentration gradient from the surface to the core of the hydrate particle, supporting the shrinking core model. Microscopic observations, however, indicated that all the crystals changed their surface morphology when exposed to the CO2 gas. Some crystals of the initial CH4 hydrate phase grew or were maintained while at the same time other crystals decreased in sizes and even disappeared over time. This observation suggested a reformation process similar to Ostwald ripening rather than an exchange of molecules in already existing hydrate structures. The experimental results from this work are presented and discussed in consideration of the existing models, providing new insights on a µm-scale into the transformation process of CH4 hydrates to CO2-rich mixed hydrates.
5
Li, Bo, You-Yun Lu, and Yuan-Le Li. "A Review of Natural Gas Hydrate Formation with Amino Acids." Journal of Marine Science and Engineering 10, no. 8 (2022): 1134. http://dx.doi.org/10.3390/jmse10081134.
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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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Kobelev, Alexey, Valery Yashin, Nikita Penkov, et al. "An Optical Microscope Study of the Morphology of Xenon Hydrate Crystals: Exploring New Approaches to Cryopreservation." Crystals 9, no. 4 (2019): 215. http://dx.doi.org/10.3390/cryst9040215.
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One of the possible approaches to a new method of cryopreservation seems to be the controlled formation of a multitude of small crystals in an object, which, due to their size, will not damage cellular structures. Managing the crystal formation, given the stochastic nature of the process, is an extremely difficult task. Theoretically, it is simplified if there is a sufficient number of changeable physical parameters, affecting the process. From this point of view, the use of ice-like gas hydrates for the purposes of cryopreservation seems to be a promising option. We investigated the process of growth of xenon gas hydrates via standard microscopy under different conditions using the specialized optical cell for observation at elevated pressures. The formation of crystals was observed in the system “supercooled liquid–xenon–water vapor” at negative, near-zero and positive values of temperature, and pressure of xenon up to 8 atmospheres. The morphology of xenon hydrate crystals observed in the experiments was analyzed and classified into five categories. The influence of physical conditions on the predominant crystal morphology was also studied. We found no evidence that the possible damaging effect of hydrate crystals should be less severe than of ice crystals.
7
Kumari, Anupama, Chandrajit Balomajumder, Amit Arora, Gaurav Dixit, and Sina Rezaei Gomari. "Physio-Chemical and Mineralogical Characteristics of Gas Hydrate-Bearing Sediments of the Kerala-Konkan, Krishna-Godavari, and Mahanadi Basins." Journal of Marine Science and Engineering 9, no. 8 (2021): 808. http://dx.doi.org/10.3390/jmse9080808.
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The characteristics of the hydrate-bearing sediments affect the formation and dissociation of gas hydrate in sediments. The mineral composition, their dispersion, and chemical composition of hydrate-bearing sediment samples plays a dominant role in the hydrate stability condition and its economic development. In this paper, the physical properties of hydrate-bearing sediment of India are compared with each other. The sediment samples are taken from the Krishan-Godavari basin (Depth—127.5 and 203.2 mbsf), Mahanadi basin (Depth—217.4 mbsf), and Kerala-Konkan basin (Depth—217.4 mbsf). The saturation of the gas hydrate observed at these sites is between 3 and 50%. Particle size is an important parameter of the sediments because it provides information on the transportation and deposition of sediment and the deposition history. In the present study, we investigated the mineralogy of hydrate-bearing sediments by chemical analysis and X-ray Diffraction. XRD, FTIR, and Raman Spectroscopy distinguished the mineralogical behavior of sediments. Quartz is the main mineral (66.8% approx.) observed in the gas hydrate-bearing sediments. The specific surface area was higher for the sediment sample from the Mahanadi basin, representing the sediments’ dissipation degree. This characterization will give important information for the possible recovery of gas from Indian hydrate reservoirs by controlling the behavior of host sediment. SEM analysis shows the morphology of the sediments, which can affect the mechanical properties of the hydrate-bearing sediments. These properties can become the main parameters to consider for the design of suitable and economic dissociation techniques for gas hydrates formed in sediments.
8
Song, Zhiguang, Shiyuan Cui, Cuiping Tang, Yong Chen, Deqing Liang, and Sibo Wang. "Effect of a Terminated PVCap on Methane Gas Hydrate Formation." Journal of Marine Science and Engineering 11, no. 2 (2023): 282. http://dx.doi.org/10.3390/jmse11020282.
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Polyvinylcaprolactam (PVCap) is an economic kinetic inhibitor for hydrate formation in pipelines during oil and gas transportation. However, its application is limited because of the low inhibition performance under certain conditions. In this work, a modified PVCap on its chain end is proposed.2-amino-3-propionic acid mercapto-terminated polyvinyl caprolactam (PVCap-NH2-COOH) was synthesized and its performance as a KHI for methane hydrate formation was evaluated under different conditions. Results showed that the performance of PVCap-NH2-COOH as a KHI was better than that of PVCap at the same concentrations. Gas hydrate samples with 1 wt.% PVCap-NH2-COOH were measured using Raman spectroscopy, XRD, and cryo-SEM. PVCap-NH2-COOH had a selective action on a specific crystal surface of the hydrates and could prevent methane molecules from entering large cages. Its inhibition ability increased with the decrease in the occupancy rate of large cages. The morphology of the gas hydrate crystal changed from porous in a pure water system to a chaotic but compact structure state in the system with PVCap-NH2-COOH.
9
Zhan, Linsen, Biao Liu, Yi Zhang, and Hailong Lu. "Rock Physics Modeling of Acoustic Properties in Gas Hydrate-Bearing Sediment." Journal of Marine Science and Engineering 10, no. 8 (2022): 1076. http://dx.doi.org/10.3390/jmse10081076.
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Gas hydrates (GH) are well known to have an influential effect on the velocity and attenuation of gas hydrate-bearing sediments (GHBS). Based on rock physics modeling, sediment velocity has been extensively used to characterize the distribution of gas hydrate. However, the results obtained from different models show a significant variation. In this study, we firstly review and compare the existing rock physics modeling for velocity and attenuation. The assumption, characteristics, theoretical basis, and workflow of the modeling are briefly introduced. The feasibility and limitations of the published models are then discussed and compared. This study provides insight into how to select a suitable rock physics model and how to conduct modeling in the application of the rock physics model to field data. Then, we introduce how to predict hydrate saturation, hydrate morphology, the dip angle of fracture, sediment permeability, and attenuation mechanisms from the comparison between the modeled and measured acoustic properties. The most important application of rock physics modeling is predicting the hydrate saturation and we discuss the uncertainties of the predicted saturation caused by the errors related to the velocity measurements or rock physics modeling. Finally, we discuss the current challenges in rock physics modeling related to optimizing the input parameters, choice of a suitable model, and upscaling problems from ultrasonic to seismic and well log frequencies.
10
Wu, Qi, Yingjie Zhao, Norimasa Yoshimoto, et al. "Strain Rate-Dependent Mechanical Response of Hydrate-Bearing Sediments under Plane Strain Condition." Journal of Marine Science and Engineering 11, no. 6 (2023): 1161. http://dx.doi.org/10.3390/jmse11061161.
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Natural gas hydrate has gained significant attention in recent years. To safely and sustainably exploit the natural gas from gas hydrate-bearing sediments, it is crucial to understand the long-term mechanical characteristics of the hydrate reservoir. In this study, the influence of hydrate and fine particles on the strain rate dependence of hydrate-bearing sediments under plane strain conditions has been studied. The experimental results show that the strain rate dependency of the mechanical properties of hydrate-bearing sediments is positively correlated with hydrate saturation instead of the morphology of hydrate in sediments. The residual strength of hydrate-bearing sediments is primarily controlled by the hydrate saturation and is independent of the strain rate. Changes in hydrate saturation and fines content can affect the relationship between the strain rate and shear band angle. Finally, the local volumetric expansion effect of hydrate-bearing sediments without fines content is more significant and shows a strong strain rate dependence characteristic. Overall, this study provides valuable insights into the long-term mechanical characteristics of hydrate reservoirs. These insights can contribute to the development of a constitutive model of hydrate-bearing sediments with time dependence in the future, which is meaningful to the exploitation of natural gas hydrate.
11
Casenave, Viviane, Aurélien Gay, and Patrice Imbert. "Spider structures: records of fluid venting from methane hydrates on the Congo continental slope." Bulletin de la Société géologique de France 188, no. 4 (2017): 27. http://dx.doi.org/10.1051/bsgf/2017189.
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Fluid seepage features on the upper continental slope offshore Congo are investigated using multi-disciplinary datasets acquired during several campaigns at sea carried out over the last 15 years. This datasets includes multibeam bathymetry, seismic data, seafloor videos, seafloor samples and chemical analyses of both carbonate samples and of the water column. Combined use of these datasets allows the identification of two distinctive associations of pockmark-like seabed venting structures, located in water depths of 600–700 m and directly above a buried structural high containing known hydrocarbon reservoirs. These two features are called spiders due to the association of large sub-circular depressions (the body) with smaller elongate depressions (the legs). Seismic reflection data show that these two structures correspond to amplitude anomalies located ca. 60–100 ms below seabed. The burial of these anomalies is consistent with the base of the methane hydrate stability domain, which leads to interpret them as patches of hydrate-related bottom-simulating reflection (BSR). The morphology and seismic character of the two structures clearly contrasts with those of the regional background (Morphotype A). The spider structures are composed of two seafloor morphotypes: Morphotype B and Morphotype C. Morphotype B makes flat-bottomed depressions associated with the presence of large bacterial mats without evidence of carbonates. Morphotype C is made of elongated depressions associated with the presence of carbonate pavements and a prolific chemosynthetic benthic life. On that basis of these observations combined with geochemical analyses, the spider structures are interpreted to be linked with methane leakage. Methane leakage within the spider structures varies from one morphotype to another, with a higher activity within the seafloor of Morphotype C; and a lower activity in the seafloor of Morphotype B, which is interpreted to correspond to a domain of relict fluid leakage. This change of the seepage activity is due to deeper changes in gas (or methane) migration corresponding to the progressive upslope migration of fluids. This phenomenon is due to the local formation of gas hydrates that form a barrier allowing the trapping of free gas below in the particular context of the wedge of hydrates.
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Xu, Zhenqiang, Yang Li, Wei Yan, et al. "Identifying Submarine Engineering Geologic Hazards in a Potential Gas Hydrate Target Area on the Southern Continental Margin of the South China Sea." Journal of Marine Science and Engineering 10, no. 12 (2022): 2008. http://dx.doi.org/10.3390/jmse10122008.
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The southern continental margin-slope area of the South China Sea is a complex passive continental margin with diverse tectonic structures and movements. This area is rich in gas hydrate resources and is also an area with a high incidence of potential geological hazards. Identifying and understanding the potential submarine geological hazards in this area is very important for disaster prevention and management during the future exploration and development of marine resources. In this paper, five types of potentially hazardous geological bodies are identified in the research area through high-precision two-dimensional seismic processing and interpretation, including submarine mounds, pockmarks, mass transport deposits, submarine collapses and faults. At the same time, the seismic reflection characteristics and the changes in its morphology and surrounding strata are described. In addition to the causes of geological hazards in this region and their influence on exploration and development, the research prospects of geological hazards in this region are also suggested. Special tectonic and sedimentary conditions, fluid activities and hydrate decomposition may be the conditions for geological hazards in this region, which pose a significant threat to the exploration and development of seabed resources and marine engineering construction in this region. Not only does our conclusion provide useful data for the development and utilization of gas hydrate, but it also presents theoretical suggestions for reducing geological hazards in the development process.
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Iwai, Hiromasa, Takaya Kawasaki, and Feng Zhang. "Constitutive model for gas hydrate-bearing soils considering different types of hydrate morphology and prediction of strength-band." Soils and Foundations 62, no. 1 (2022): 101103. http://dx.doi.org/10.1016/j.sandf.2021.101103.
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Fang, Qingchao, Xin Zhao, Sunbo Li, Zhengsong Qiu, Zhiyuan Wang, and Qi Geng. "Effect of Surfactants with Different Hydrophilic–Lipophilic Balance on the Cohesive Force between Cyclopentane Hydrate Particles." Journal of Marine Science and Engineering 10, no. 9 (2022): 1255. http://dx.doi.org/10.3390/jmse10091255.
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Effective control of the cohesive force between hydrate particles is the key to prevent their aggregation, which then causes pipeline blockage. The hydrophilic–lipophilic balance (HLB) value of surfactants was proposed as an important parameter for the evaluation and design of hydrate anti-agglomerants. A microscopic manipulation method was used to measure the cohesive forces between cyclopentane hydrate particles in the presence of Tween and Span series surfactants with different HLB values; moreover, the measured cohesive force was compared with the results of calculations based on the liquid bridge force model. Combined with the surface morphology and wettability of the hydrate particles, we analyzed the mechanism by which surfactants with different HLB values influence the cohesion between hydrate particles. The results show that for both Tween (hydrophilic, HLB > 10) and Span (hydrophobic, HLB < 10) surfactants, the cohesive force between cyclopentane hydrate particles decreased with decreasing HLB. The experimental results were in good agreement with the results of calculations based on the liquid bridge force model. The cohesive force between hydrate particles increased with increasing concentration of Tween surfactants, while in the case of the Span series, the cohesive force decreased with increasing surfactant concentration. In the formation process of cyclopentane hydrate particles, the aggregation of low-HLB surfactant molecules at the oil–water or gas–water interface increases the surface roughness and hydrophobicity of the hydrate particles and inhibits the formation of liquid bridges between particles, thus reducing the cohesion between particles. Therefore, the hydrate aggregation and the associated blockage risks can be reduced.
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Khimenkov, Aleksandr Nikolaevich, Andrei Viktorovich Koshurnikov, and Julia Viktorovna Stanilovskaya. "Geosystems of gas-saturated permafrost." Арктика и Антарктика, no. 2 (February 2020): 65–105. http://dx.doi.org/10.7256/2453-8922.2020.2.32698.
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The object of this&nbsp;study is the geosystems of gas-saturated permafrost. Currently, the theoretical basis for examination of gas component in permafrost is practically not developed. At the same time, the theoretical and practical significance of this problem has rapidly increased in recent years. This is due to gas emissions during drilling of wells in frozen rocks, the identification of significant greenhouse gas emissions in the Arctic, the detection of previously unknown processes in the permafrost zone &ndash; the formation of craters due to gas emissions.The main method applied in the article is the analysis of research materials. The synthesis of the results was carried out on the basis of the geosystem approach. The authors are first to demonstrate that gas-saturated zones in seasonally and permafrost rocks have all the attributes of geosystems: localization in space, boundaries, morphology, individual structure and properties, development history, life cycle, hierarchy.&nbsp;Five types of geosystem were determined: active layer; genetic type; confined to geological structures; secondary, associated with the decomposition of gas hydrates in vivo; technogenic (due to thermal or mechanical effects on hydrated and gas saturated frozen rocks). The artcile describes promising directions in studying gas-saturated geosystems of permafrost zone, as well as&nbsp;&nbsp;the advanced research methods.
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Gulina, L. B., I. Skvortsova, and L. I. Kuklo. "Formation of Hydrated Titanium Dioxide on the Surface of Aqueous Solution of Titanium(III, IV) Salt under the Action of Ammonia Gas." Журнал общей химии 93, no. 2 (2023): 314–21. http://dx.doi.org/10.31857/s0044460x2302018x.
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During the interaction at the phase boundary, the aqueous interface between the titanium salt solution and air (NH3) gives rise to TiO2 · n H2O films consisting of nanoparticles about 20 nm in size. The morphology of products synthesized on the surface of TiOSO4, TiCl3, Ti2(SO4)3 solutions was studied by optical and electron microscopy. Using X-ray spectral microanalysis and X-ray phase analysis, the composition and crystal structure of the synthesized compounds were established. The conditions for obtaining tubular TiO2 · n H2O structures with the morphology of microscrolls about 10 µm in diameter and 200 to 600 µm in length were found. Possible reactions for the formation of gradient films of hydrated titanium dioxide and a hypothesis to explain the reasons for their transformation into microscrolls are proposed.
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Khimenkov, Aleksandr Nikolaevich, Andrei Viktorovich Koshurnikov, and Julia Viktorovna Stanilovskaya. "Parageneses of cryogenic formations of gas emission funnels (Part 1). Morphology of cryogenic formations." Арктика и Антарктика, no. 2 (February 2021): 27–52. http://dx.doi.org/10.7256/2453-8922.2021.2.35500.
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The subject of this research is the cryogenic formations found in gas emission funnels in the north of Western Siberia.&nbsp;The object of this research is cryogenic processes that prepare the explosion, which forms a gas emission funnel.&nbsp;The study of cryogenic structures that shape the walls of gas emission funnels is based on the structural-genetic analysis, which reveals the peculiarities of the initial cryogenic structure of frozen rock, as well as the cryogenic textures modified as a result of dynamic metamorphism.&nbsp;The authors examine such aspects of the topic as the general&nbsp;orientation of plastic and explosive deformations under the influence of high pressure.&nbsp;Analysis is conducted on the role of intra-ground gas filtration in transformation of the initial cryogenic structure.&nbsp;Special attention is given to the patterns of emergence and development of the local geodynamic system that ultimately substantiates the formation of gas emission funnel.&nbsp;The novelty of this research consists in the establishment of paragenetic relations between the processes of gas filtration and deformations of gas-saturated ice surface material (from viscoplastic motion to brittle fracture).&nbsp;The main conclusions are as follows: such external influences as increase in the temperature or pressure change thermodynamic conditions, which lead to multi-phase structural transformation of the initial cryogenic structure of the cryolithic zone;&nbsp;a series of plastic and explosive deformations instigates the intense heat and mass transfer, redistributing the substance in the liquid, solid and gaseous state; in frozen rocks, ice is the most deformable component, thus, most information on the processes preceding the formation of gas funnels can be acquired by studying the morphology of cryogenic formations observed in the walls of the funnels, as well as in the unthawed fragments of frozen rocks thrown to the surface.&nbsp;The authors&rsquo; special contribution lies in examination of the complete lifecycle of the development of selected geosystems, from the initial stage &ndash;&nbsp; formation of conditions for decomposition of the gas hydrates, to the final stage &ndash; explosion and emission of ice surface material.
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Chang, Jingyi, Yuanyuan Li, and Hailong Lu. "The Morphological Characteristics of Authigenic Pyrite Formed in Marine Sediments." Journal of Marine Science and Engineering 10, no. 10 (2022): 1533. http://dx.doi.org/10.3390/jmse10101533.
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Pyrites are widely distributed in marine sediments, the morphology of which is applied as a proxy to infer the redox conditions of bottom water, and identify diagenetic stages and hydrocarbon leakage activities. In this review, the methods used for the morphological study of pyrite are summarized. The textural and size characteristics of euhedral pyrite and pyrite aggregates, as the formation and evolution mechanism of pyrite are discussed for their significance in reconstructing the geochemical environment. The morphological study of pyrite includes shape observation, size estimation, and surface feature analysis. Scanning electron microscope and optical microscope are the main methods for morphological observation; transmission electron microscope and scanning tunneling microscope are applicable to observe nanoscale morphological structures and crystal growth on the crystal surface, and X-ray computed tomography is capable of measuring pyrite size distribution at the scale of a micrometer. Under the marine sedimentary condition, the single crystal of pyrite appears in cube, octahedron, dodecahedron, and their intermediates, the size of which ranges from several nanometers to more than 100 µm. The morphology of euhedral pyrite is controlled by temperature, pH, the chemical composition of interstitial water, etc., and might have been experienced in later reformation processes. The pyrite aggregates occur as framboid, rod-like, fossil-infilling, etc., characterized by the comparatively large size of several microns to several millimeters. It is found that certain textures correspond with different formation mechanisms and geochemical environments. Particularly, under special geological conditions, for instance, the methane leakage and/or decomposition of gas hydrate, pyrite is anomaly enriched with morphological textures of massive framboid cluster, rod-like aggregates, etc., and framboid is found with a large mean diameter (>20 µm) and standard deviation (>10 µm). These typical features can be employed to ascertain the position of the paleo sulfate methane transition zone (SMTZ).
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Guragain, Deepa, Camila Zequine, Ram K. Gupta, and Sanjay R. Mishra. "Facile Synthesis of Bio-Template Tubular MCo2O4 (M = Cr, Mn, Ni) Microstructure and Its Electrochemical Performance in Aqueous Electrolyte." Processes 8, no. 3 (2020): 343. http://dx.doi.org/10.3390/pr8030343.
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In this project, we present a comparative study of the electrochemical performance for tubular MCo2O4 (M = Cr, Mn, Ni) microstructures prepared using cotton fiber as a bio-template. Crystal structure, surface properties, morphology, and electrochemical properties of MCo2O4 are characterized using X-ray diffraction (XRD), gas adsorption, scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), cyclic voltammetry (CV), and galvanostatic charge-discharge cycling (GCD). The electrochemical performance of the electrode made up of tubular MCo2O4 structures was evaluated in aqueous 3M KOH electrolytes. The as-obtained templated MCo2O4 microstructures inherit the tubular morphology. The large-surface-area of tubular microstructures leads to a noticeable pseudocapacitive property with the excellent electrochemical performance of NiCo2O4 with specific capacitance value exceeding 407.2 F/g at 2 mV/s scan rate. In addition, a Coulombic efficiency ~100%, and excellent cycling stability with 100% capacitance retention for MCo2O4 was noted even after 5000 cycles. These tubular MCo2O4 microstructure display peak power density is exceeding 7000 W/Kg. The superior performance of the tubular MCo2O4 microstructure electrode is attributed to their high surface area, adequate pore volume distribution, and active carbon matrix, which allows effective redox reaction and diffusion of hydrated ions.
20
Kokhan, A. V., E. A. Eremenko, Е. А. Moroz, Ermakov A.V., and Sokolov S.Yu. "Fluidogenic landforms on the Arctic shelves." Lomonosov Geography Journal 79, no. 2 (2024) (2024): 91–107. http://dx.doi.org/10.55959/10.55959/msu0579-9414.5.79.2.8.
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The paper summarizes and systematizes available data on geological and geomorphologic structure of fluidogenic landforms on the Arctic shelves, in particular, pockmarks, pingo-like features, domes and craters. A small-scale map of the spatial distribution of fluidogenic landforms has been compiled. Geographical patterns of distribution of different types of fluidogenic landforms in the Arctic seas were identified, as well as main factors and conditions that determine their localization, morphology and modern activity. It is shown that fluidogenic landforms are complex formations with a multi-component source of fluids. Their distribution and accompanying gas manifestations in bottom sediments and water column are determined by complex combinations of factors. Among them the most significant are distribution and thickness of subaquatic permafrost and subpermafrost and the near-surface deep-sea gas hydrates. The amount of fluidogenic landforms at the bottom is influenced by specific features of oil and gas bearing structures and rocks with reservoir properties, as well as the influx of fresh land waters along the base of permafrost on the shelf, the degree of salinity of bottom sediments and the temperature of near-bottom water. In addition, fluidogenic morpholithogenesis is facilitated by the presence of structural channels for the influx of fluids to the surface in the form of faults and gas pipes in bottom sediments with the possible contribution of the jet degassing effect to the new formation of frozen rocks, accompanied by bottom heaving. Morphological differences in the structure of fluidogenic landforms are associated, in addition to the factors indicated above, with the history of the geological development of the shelf, in particular, with the time of submersion during the Holocene transgression and the impact of glaciation.
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Lackey, J. K., G. F. Moore, M. Strasser, A. Kopf, and C. S. Ferreira. "Spatial and temporal cross-cutting relationships between fault structures and slope failures along the outer Kumano Basin and Nankai accretionary wedge, SW Japan." Geological Society, London, Special Publications 477, no. 1 (2018): 23–36. http://dx.doi.org/10.1144/sp477.10.
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AbstractNew, high-resolution multi-beam bathymetric data from RV Sonne cruise SO251 show a widely variable surface morphology along the southern Kumano Basin and Nankai accretionary prism off SW Japan. Combined with a three-dimensional seismic volume, these data provide insight into the ubiquitous and varied nature of faulting typical of accretionary prism settings, a high number of submarine landslides across the entire study area that vary both spatially and temporally, a pronounced absence of slide deposit bathymetric manifestations, widely varied slope angles and a potential subducted seamount scar. We have mapped scars of 442 primary and 184 secondary landslides and have measured the areas evacuated by these slides. Most of the slides are completely disintegrative, so surficial landslide deposits are almost absent. The incidence with which temporally sequential slope failures and fault structures cross-cut themselves and one another provides evidence of potential failure pre-conditioning such as gas hydrates, pore fluid overpressures and bottom current activity. Seismic loading and slope over-steepening are then the most likely final trigger mechanisms to slope failure. The majority of observed landslides (64%) occur seawards of the outer ridge, providing insight into the relationship between surficial landsliding and subsurface tectonic processes along this accretionary prism.
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Korotcenkov, Ghenadii, Sang Han, Beongki Cho, and Valeri Tolstoy. "Structural characterization and phase transformations in metal oxide films synthesized by successive ionic layer deposition (SILD) method." Processing and Application of Ceramics 3, no. 1-2 (2009): 19–28. http://dx.doi.org/10.2298/pac0902019k.
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In this paper the peculiarities of phase composition and morphology of metal oxides synthesized by successive ionic layer deposition (SILD) method are discussed. The main attention is focused on SnO2-based metal oxides, which are promising materials for gas sensor applications. FTIR spectroscopy has shown that the precipitates of metal oxides, deposited by SILD method, are hydroxide, peroxide or hydrated metal oxide-based compounds. After annealing at relatively low temperatures (200-400?C) these compounds release both water and peroxide oxygen and transform into corresponding oxides. According to XRD, SEM and AFM measurements it was confirmed that deposited films had fine-dispersed structures. Only after annealing at Tan>500?C, XRD diffraction peaks, typical for nanocrystalline material with grain size < 6-8 nm, were observed. High roughness and high degree of agglomeration are important peculiarities of metal oxides deposited by SILD. Metal oxide films consist of spherical agglomerates. Degree of agglomeration of the films and agglomerate size could be controlled. It was found that introduction of various additives in the solution for SILD could sufficiently change the microstructure of synthesized metal oxides. .
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Loveday, J. S., R. J. Nelmes, M. Guthrie, D. D. Klug, and J. S. Tse. "New gas hydrate structures." Acta Crystallographica Section A Foundations of Crystallography 58, s1 (2002): c362. http://dx.doi.org/10.1107/s0108767302099464.
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Pandey, Jyoti Shanker, Charilaos Karantonidis, Adam Paul Karcz, and Nicolas von Solms. "Enhanced CH4-CO2 Hydrate Swapping in the Presence of Low Dosage Methanol." Energies 13, no. 20 (2020): 5238. http://dx.doi.org/10.3390/en13205238.
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CO2-rich gas injection into natural gas hydrate reservoirs is proposed as a carbon-neutral, novel technique to store CO2 while simultaneously producing CH4 gas from methane hydrate deposits without disturbing geological settings. This method is limited by the mass transport barrier created by hydrate film formation at the liquid–gas interface. The very low gas diffusivity through hydrate film formed at this interface causes low CO2 availability at the gas–hydrate interface, thus lowering the recovery and replacement efficiency during CH4-CO2 exchange. In a first-of-its-kind study, we have demonstrate the successful application of low dosage methanol to enhance gas storage and recovery and compare it with water and other surface-active kinetic promoters including SDS and L-methionine. Our study shows 40–80% CH4 recovery, 83–93% CO2 storage and 3–10% CH4-CO2 replacement efficiency in the presence of 5 wt% methanol, and further improvement in the swapping process due to a change in temperature from 1–4 °C is observed. We also discuss the influence of initial water saturation (30–66%), hydrate morphology (grain-coating and pore-filling) and hydrate surface area on the CH4-CO2 hydrate swapping. Very distinctive behavior in methane recovery caused by initial water saturation (above and below Swi = 0.35) and hydrate morphology is also discussed. Improved CO2 storage and methane recovery in the presence of methanol is attributed to its dual role as anti-agglomerate and thermodynamic driving force enhancer between CH4-CO2 hydrate phase boundaries when methanol is used at a low concentration (5 wt%). The findings of this study can be useful in exploring the usage of low dosage, bio-friendly, anti-agglomerate and hydrate inhibition compounds in improving CH4 recovery and storing CO2 in hydrate reservoirs without disturbing geological formation. To the best of the authors’ knowledge, this is the first experimental study to explore the novel application of an anti-agglomerate and hydrate inhibitor in low dosage to address the CO2 hydrate mass transfer barrier created at the gas–liquid interface to enhance CH4-CO2 hydrate exchange. Our study also highlights the importance of prior information about methane hydrate reservoirs, such as residual water saturation, degree of hydrate saturation and hydrate morphology, before applying the CH4-CO2 hydrate swapping technique.
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Pedchenko, Larysa, and Mykhailo Pedchenko. "Increasing the thermal resistance of shell gas-support structures for use as gas hydrates storages." Technology audit and production reserves 3, no. 1(65) (2022): 27–33. http://dx.doi.org/10.15587/2706-5448.2022.259738.
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Currently, in the world and Ukraine there are difficulties with the provision of natural gas. However, one of the problems is its storage. So, the object of research is the process of storing natural gas in land storages in gas hydrate form. An alternative to traditional technologies can be the transportation and long-term storage of natural gas in the form of gas hydrates. However, the existing reinforced concrete and metal structures, in addition to a significant price, also cannot sufficiently provide effective thermal insulation of the gas hydrate and its tightness. The paper substantiates the possibility of using gas support structures and pneumatic building structures as gas hydrate storage facilities. The possibility of improving the proposed structures by using non-hardening foams as a thermal insulation material has been proposed and confirmed by calculations. The study was aimed at calculating and analyzing the effectiveness of such a method of thermal insulation of a ground gas storage facility for storing natural gas in gas hydrate form. A method acceptable for the current level of technology development is proposed for increasing the thermal resistance of gas support structures for their use as gas storages in the gas hydrate state. It consists in using stable liquid foams as an effective thermal insulation material to fill the space between the layers of a two-layer coating. In the course of the study, the high efficiency of the proposed method of thermal insulation of ground hydrate reservoirs with stable liquid foams was shown. Calculation of thermodynamic characteristics of gas support storages for gas hydrates at their thermal insulation by liquid foam is made. The efficiency of the technological process of storing gas hydrate in the form of blocks is analyzed depending on the time of year. The main parameters of operation of such facilities are substantiated. It has been established that storage of hydrate blocks in storage without their dissociation during insulation with a layer of foam requires short-term additional cooling during the summer period of storage. Thus, this technology has prospects for widespread adoption.
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Kutnyi, Bogdan, and . "Termotechnical Characteristics Determination of Enclosing Structures for Hydrates Storage." International Journal of Engineering & Technology 7, no. 3.2 (2018): 510. http://dx.doi.org/10.14419/ijet.v7i3.2.14580.
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In many countries around the world, gas hydrates use is seen as a promising alternative source of energy. The industrial infrastructure gas hydrates use requires the creation of reliable means for their storage and transportation.In the paper the research installations schemes and the dissociated gas temperature regime hydrate experimental study results are given. The surface and propane hydrate deep layers temperature regime, which decomposes under atmospheric pressure, is analyzed. Convective and radiant heat transfer at the hydrate storage reservoir inner surface is considered and the temperature at the gas hydrates surface is determined. The method for determining the resistance to the tent heat transfer is developed and the dependence for the propane hydrate dissociation intensity is established. The research results can be used to reduce gas losses during gas hydrates storage and transportation under nonequilibrium conditions.
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B Aminu, Muslim, and Samuel B Ojo. "Seafloor morphology and potential gas hydrate distribution in the offshore Niger Delta." International Journal of Advanced Geosciences 12, no. 1 (2024): 17–26. http://dx.doi.org/10.14419/wwajt225.
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Bottom simulating reflectors (BSRs) and seismic pipe features have been used as proxies for defining the distribution of gas hydrate sediments in the offshore Niger Delta. This is the most extensive mapping of gas hydrate sediments in the Delta as of today. The seismic data merge comes from multiple surveys acquired with different parameters and seismic resolutions over the course of decades of oil and gas exploration in the region. Indicated gas hydrate distribution generally follows the structural fabric of the Niger Delta with BSRs occurring along the apexes of the thrust-related ridges that have bathymetric relief on the seafloor. The presence of swarms of seismic pipe features landwards of BSR locations suggests hydrates occur beyond BSR locations. The potential gas hydrates sediment acreage in offshore Niger Delta is 17600 sq-km, representing 20% of the area with a thickness of the gas hydrate stability zone reaching 440 m in the more outboard regions of the Delta. Total gas hydrates sediment coverage likely exceeds this value as BSRs become indistinguishable from sediment strata in regions of flat dips. The presence of double BSRs further suggests the presence of thermogenic gas hydrates in the region and allows to extend the thickness of the potential hydrate zone to 550 m in the outboard regions of the Delta.
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Larysa, Pedchenko, and Pedchenko Mykhailo. "Increasing the thermal resistance of shell gas-support structures for use as gas hydrates storages." Technology audit and production reserves 3, no. 1(65) (2022): 27–33. https://doi.org/10.15587/2706-5448.2022.259738.
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<em>Currently, in the world and Ukraine there are difficulties with the provision of natural gas. However, one of the problems is its storage. So, the object of research is the process of storing natural gas in land storages in gas hydrate form. An alternative to traditional technologies can be the transportation and long-term storage of natural gas in the form of gas hydrates. However, the existing reinforced concrete and metal structures, in addition to a significant price, also cannot sufficiently provide effective thermal insulation of the gas hydrate and its tightness.</em> <em>The paper substantiates the possibility of using gas support structures and pneumatic building structures as gas hydrate storage facilities. The possibility of improving the proposed structures by using non-hardening foams as a thermal insulation material has been proposed and confirmed by calculations. The study was aimed at calculating and analyzing the effectiveness of such a method of thermal insulation of a ground gas storage facility for storing natural gas in gas hydrate form.</em> <em>A method acceptable for the current level of technology development is proposed for increasing the thermal resistance of gas support structures for their use as gas storages in the gas hydrate state. It consists in using stable liquid foams as an effective thermal insulation material to fill the space between the layers of a two-layer coating. In the course of the study, the high efficiency of the proposed method of thermal insulation of ground hydrate reservoirs with stable liquid foams was shown.</em> <em>Calculation of thermodynamic characteristics of gas support storages for gas hydrates at their thermal insulation by liquid foam is made. The efficiency of the technological process of storing gas hydrate in the form of blocks is analyzed depending on the time of year. The main parameters of operation of such facilities are substantiated. It has been established that storage of hydrate blocks in storage without their dissociation during insulation with a layer of foam requires short-term additional cooling during the summer period of storage. Thus, this technology has prospects for widespread adoption.</em>
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Pan, Haojie, Hongbing Li, Jingyi Chen, et al. "Evaluation of gas hydrate resources using hydrate morphology-dependent rock physics templates." Journal of Petroleum Science and Engineering 182 (November 2019): 106268. http://dx.doi.org/10.1016/j.petrol.2019.106268.
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Jiang, Lanlan, Nan Xu, Qingbin Liu, ZuCheng Cheng, Yu Liu, and Jiafei Zhao. "Review of Morphology Studies on Gas Hydrate Formation for Hydrate-Based Technology." Crystal Growth & Design 20, no. 12 (2020): 8148–61. http://dx.doi.org/10.1021/acs.cgd.0c01331.
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Sun, Jianye, Chengfeng Li, Xiluo Hao, Changling Liu, Qiang Chen, and Daigang Wang. "Study of the Surface Morphology of Gas Hydrate." Journal of Ocean University of China 19, no. 2 (2019): 331–38. http://dx.doi.org/10.1007/s11802-020-4039-7.
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Ma, Chaozheng, Xiaoxu Hu, Hongxiang Si, et al. "Formation Kinetics and Morphology Characteristics of Natural Gas Hydrates in Sandstone Fractures." Applied Sciences 15, no. 13 (2025): 7399. https://doi.org/10.3390/app15137399.
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Fractures in marine sediments are critical zones for hydrate formation. The kinetics and morphological characteristics of hydrates within sandstone fractures are comprehensively investigated in this study by employing a high-pressure visualization reaction vessel to examine their formation, dissociation, and reformation processes. The results are presented below: (1) In 3 mm Type I fractures, the induction time is longer than that observed in the other two fracture widths. Hydrates predominantly form on the fracture walls and gradually expand toward both sides of the fracture. (2) Gas enters the fracture from multiple directions, causing the hydrate in Type X fractures to expand toward the center from all sides, which shortens the induction time and increases the quantity of hydrate formation. (3) An increase in fracture roughness promotes nucleation of the hydrate at surface protrusions but inhibits the total quantity of hydrate formation. (4) Hydrate dissociation typically propagates from the fracture wall into the interior, exhibiting a wavy surface morphology. Gas production is influenced by the fracture width, with the highest gas production observed in a 3 mm fracture. (5) Due to the memory effect, the hydrate induction time for reformation is significantly shorter, though the quantity of hydrate formed is lower than that of the first formation. This study aims to provide micro-level insights into the distribution of hydrates in sandstone fractures, thereby facilitating more efficient and safe extraction of hydrates from fractures.
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Takeya, S., Y. Kamata, T. Uchida, et al. "Coexistence of structure I and II hydrates formed from a mixture of methane and ethane gases." Canadian Journal of Physics 81, no. 1-2 (2003): 479–84. http://dx.doi.org/10.1139/p03-038.
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X-ray diffraction measurements were conducted to determine the hydrate structures formed from a mixture of CH4 and C2H6 gases at 263 K. With increasing initial fractions of C2H6 in the gas, the crystal structures of the hydrate were structure I, structure I + structure II, structure II, structure I + structure II, and structure I. In situ observations of the growth processes of the mixed gas hydrates under constant gas concentration suggest that the coexistence of structure I and structure II hydrate were caused by occurrences of metastable hydrate structure. PACS No.: 82.75Fq
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Zeng, H., L. D. Wilson, V. K. Walker, and J. A. Ripmeester. "The inhibition of tetrahydrofuran clathrate-hydrate formation with antifreeze protein." Canadian Journal of Physics 81, no. 1-2 (2003): 17–24. http://dx.doi.org/10.1139/p03-001.
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The effect of Type I fish antifreeze protein (AFP) from the winter flounder, Pleuronectes americanus (Walbaum), (WfAFP) on the formation of tetrahydrofuran (THF) clathrate hydrate was studied by observing changes in THF crystal morphology and determining the induction time for nucleation. AFP retarded THF clathrate-hydrate growth at the tested temperatures and modified the THF clathrate-hydrate crystal morphology from octahedral to plate-like. AFP appears to be even more effective than the kinetic inhibitor, polyvinylpyrrolidone (PVP). Recombinant AFP from an insect, a spruce budworm, Choristoneura fumiferana (Clem.), moth, (Cf) was also tested for inhibition activity by observation of the THF-hydrate-crystal-growth habit. Like WfAFP, CfAFP appeared to show adsorption on multiple THF-hydrate-crystal faces. A protein with no antifreeze activity, cytochrome C, was used as a control and it neither changed the morphology of the THF clathrate-hydrate crystals, nor retarded the formation of the hydrate. Preliminary experiments on the inhibition activity of WfAFP on a natural gas hydrate assessed induction time and the amount of propane gas consumed. Similar to the observations for THF, the data indicated that WfAFP inhibited propane-hydrate growth. Taken together, these results support our hypothesis that AFPs can inhibit clathrate-hydrate growth and as well, offer promise for the understanding of the inhibition mechanism. PACS No.: 87.90ty
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Chen, Yu Feng, De Qing Liang, and Neng You Wu. "In Situ Measurement of Electrical Resistivity of Ocean Sediments Containing Gas Hydrates." Applied Mechanics and Materials 432 (September 2013): 104–8. http://dx.doi.org/10.4028/www.scientific.net/amm.432.104.
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An understanding of the physical properties of hydrate-bearing sediment is necessary for interpretation of geophysical data collected in field settings. We have conducted a laboratory experiment to measure the electrical property of initially water saturated sediment containing natural gas hydrate. When gas hydrate was formed from pore fluid in ocean sediment, bulk sediment resistivity was significantly increased. The resistivity of the sediment was largely changed below 20% hydrate saturation. With the increasing hydrate saturation, the resistivity of sediment was increased and the resistivity of pore fluid was decrease. In the final process of hydrate formation, the resistivity depression was found mainly due to the transition of gas hydrate morphology. The electrical resistivity of hydrate specimens varied from 1.930 Ohm.m to 3.950 Ohm.m for saturation ranging from 0% to 52.68%. Besides, the dependence of the resistivity index versus hydrate saturation is inconsistent with Archies law. The results of our studies have important implications for quantitative laboratory and field calibration of geophysical measurements within gas hydratebearing intervals.
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Gabitto, Jorge F., and Costas Tsouris. "Physical Properties of Gas Hydrates: A Review." Journal of Thermodynamics 2010 (January 12, 2010): 1–12. http://dx.doi.org/10.1155/2010/271291.
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Methane gas hydrates in sediments have been studied by several investigators as a possible future energy resource. Recent hydrate reserves have been estimated at approximately 1016 m3 of methane gas worldwide at standard temperature and pressure conditions. In situ dissociation of natural gas hydrate is necessary in order to commercially exploit the resource from the natural-gas-hydrate-bearing sediment. The presence of gas hydrates in sediments dramatically alters some of the normal physical properties of the sediment. These changes can be detected by field measurements and by down-hole logs. An understanding of the physical properties of hydrate-bearing sediments is necessary for interpretation of geophysical data collected in field settings, borehole, and slope stability analyses; reservoir simulation; and production models. This work reviews information available in literature related to the physical properties of sediments containing gas hydrates. A brief review of the physical properties of bulk gas hydrates is included. Detection methods, morphology, and relevant physical properties of gas-hydrate-bearing sediments are also discussed.
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Zhang, Zijian, De-hua Han, and Qiuliang Yao. "Quantitative interpretation for gas hydrate accumulation in the eastern Green Canyon Area, Gulf of Mexico using seismic inversion and rock physics transform." GEOPHYSICS 76, no. 4 (2011): B139—B150. http://dx.doi.org/10.1190/1.3581358.
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Gas hydrate can be interpreted from seismic data through observation of bottom simulating reflector (BSR). It is a challenge to interpret gas hydrate without BSR. Three-dimensional qualitative and quantitative seismic interpretations were used to characterize gas hydrate distribution and concentration in the eastern Green Canyon area of the Gulf of Mexico, where BSR is absent. The combination of qualitative and quantitative interpretation reduces ambiguities in the estimation and identification of gas hydrate. Sandy deposition and faults are qualitatively interpreted from amplitude data. The 3D acoustic impedance volume was interpreted in terms of high P-impedance hydrate zones and low P-impedance free gas zones. Gas hydrate saturation derived from P-impedance is estimated by a rock physics transform. We interpreted gas hydrate in the sand-prone sediments with a maximum saturation of approximately 50% of the pore space. Sheet-like and some bright spot gas hydrate accumulations are interpreted. The interpretation of sheet-like gas hydrate within sand-prone sediments around faults suggests that fluid moves into the sand zones laterally by conduits. Variations in depths of interpreted gas hydrate zones imply nonequilibrium conditions. Low P-impedance free gas zones within high P-impedance gas hydrate zones imply possible coexistence of hydrate and free gas within the hydrate stability zone. We propose that gas hydrate distribution and concentration are associated with structures, buried sedimentary bodies, sources of gas, and fluid flux.
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Pandey, Jyoti Shanker, Yousef Jouljamal Daas, Adam Paul Karcz, and Nicolas von Solms. "Enhanced Hydrate-Based Geological CO2 Capture and Sequestration as a Mitigation Strategy to Address Climate Change." Energies 13, no. 21 (2020): 5661. http://dx.doi.org/10.3390/en13215661.
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Geological sequestration of CO2-rich gas as a CO2 capture and storage technique has a lower technical and cost barrier compared to industrial scale-up. In this study, we have proposed CO2 capture and storage via hydrate in geological formation within the hydrate stability zone as a novel technique to contribute to global warming mitigation strategies, including carbon capture, utilization, and storage (CCUS) and to prevent vast methane release into the atmosphere caused by hydrate melting. We have attempted to enhance total gas uptake and CO2 capture efficiency in hydrate in the presence of kinetic promoters while using diluted CO2 gas (CO2-N2 mixture). Experiments are performed using unfrozen sands within hydrate stability zone condition and in the presence of low dosage surfactant and amino acids. Hydrate formation parameters, including sub-cooling temperature, induction time, total gas uptake, and split fraction, are calculated during the single-step formation and dissociation process. The effect of sands with varying particle sizes (160–630 µm, 1400–5000 µm), low dosage promoter (500–3000 ppm) and CO2 concentration in feed gas (20–30 mol%) on formation kinetic parameters was investigated. Enhanced formation kinetics are observed in the presence of surfactant (1000–3000 ppm) and hydrophobic amino acids (3000 ppm) at 120 bar and 1 ℃ experimental conditions. We report induction time in the range of 7–170 min and CO2 split fraction (0.60–0.90) in hydrate for 120 bar initial injection pressure. CO2 split fraction can be enhanced by reducing sand particle size or increasing the CO2 mol% in incoming feed gas at given injection pressure. This study also reports that formation kinetics in a porous medium are influenced by hydrate morphology. Hydrate morphology influences gas and water migration within sediments and controls pore space or particle surface correlation with the formation kinetics within coarse sediments. This investigation demonstrates the potential application of bio-friendly amino acids as promoters to enhance CO2 capture and storage within hydrate. Sufficient contact time at gas-liquid interface and higher CO2 separation efficiency is recorded in the presence of amino acids. The findings of this study could be useful in exploring the promoter-driven pore habitat of CO2-rich hydrates in sediments to address climate change.
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Li, Xingxun, Cunning Wang, Qingping Li, Qi Fan, Guangjin Chen, and Changyu Sun. "Study on the Growth Kinetics and Morphology of Methane Hydrate Film in a Porous Glass Microfluidic Device." Energies 14, no. 20 (2021): 6814. http://dx.doi.org/10.3390/en14206814.
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Natural gas hydrates are widely considered one of the most promising green resources with large reserves. Most natural gas hydrates exist in deep-sea porous sediments. In order to achieve highly efficient exploration of natural gas hydrates, a fundamental understanding of hydrate growth becomes highly significant. Most hydrate film growth studies have been carried out on the surface of fluid droplets in in an open space, but some experimental visual works have been performed in a confined porous space. In this work, the growth behavior of methane hydrate film on pore interior surfaces was directly visualized and studied by using a transparent high-pressure glass microfluidic chip with a porous structure. The lateral growth kinetics of methane hydrate film was directly measured on the glass pore interior surface. The dimensionless parameter (−∆G/(RT)) presented by the Gibbs free energy change was used for the expression of driving force to explain the dependence of methane hydrate film growth kinetics and morphology on the driving force in confined pores. The thickening growth phenomenon of the methane hydrate film in micropores was also visualized. The results confirm that the film thickening growth process is mainly determined by water molecule diffusion in the methane hydrate film in glass-confined pores. The findings obtained in this work could help to develop a solid understanding on the formation and growth mechanisms of methane hydrate film in a confined porous space.
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Li, Gang, Fugui Tang, Chaofan Li, Wen Lei, and Ying Liu. "Improved Detectivity for Detecting Gas Hydrates Using the Weighted Differential Fields of the Marine Controlled-Source Electromagnetic Data." Journal of Marine Science and Engineering 10, no. 2 (2022): 161. http://dx.doi.org/10.3390/jmse10020161.
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Gas hydrate is seen as a kind of new energy resources, yet it may also be one of the main greenhouse gases as its dissociation may release methane into the atmosphere. Furthermore, a severe hazard to offshore infrastructures may also be introduced by extensive gas hydrate dissociation associated with the stability of the geological structures after gas production. Therefore, it is essential to investigate the gas hydrate as well as its environmental impacts before drilling and extracting it. The geophysical seismic reflection data is usually used for exploring the gas hydrate. The gas hydrate can be effectively identified by the bottom simulating reflectors (BSRs) on seismic reflection data. However, the BSR is only for identifying the bottom boundary and it is difficult to estimate its space distribution and saturation within the hydrate stability zone. The marine controlled-source electromagnetic (CSEM) data is suitable for detecting the gas hydrate as the resistivity of the seafloor increases significantly in the presence of gas hydrate or free gas. In this study, a weighted differential-field method is applied to improve the detectivity for identifying the gas hydrate. Numerical tests show that the difference of the EM fields can effectively suppress the airwaves in shallow waters. Therefore, the detectivity given by the field ratio between the models with and without the gas hydrate target is enhanced.
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Pedchenko, Nazar. "Development of methods of operative determination of parameters of repeated hydrate formation in layer systems of gas hydrate deposits." Technology audit and production reserves 3, no. 1(65) (2022): 34–38. http://dx.doi.org/10.15587/2706-5448.2022.259263.
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The object of research is the methods of laboratory setting of the parameters of hydrate formation of well production and the design features of the equipment for its implementation. Methane hydrate is becoming a promising topic for a new energy resource. At the same time, hydrostatic formation is one of the most problematic areas in ensuring the transport of well products, and this primarily concerns the production of gas hydrate deposits. An analysis of the thermobaric parameters of the well production of gas hydrate deposits shows that when they are moved by technological lines, they are close to hydrate equilibrium, but due to the intensity of the process, the system does not have time to reach it. In addition, reservoir system water has a memory of hydrate structures, or a certain amount of gas hydrate solid phase is also present in the flow water. In this regard, a set of laboratory studies was carried out to assess the nature of the behavior of this type of systems during the re-crystallization of gas hydrate and its dissociation. Based on the results of the research, a method for the operational laboratory setting of the parameters of repeated hydrate formation in reservoir systems of gas hydrate deposits was developed. It provides for setting the parameters of mass crystallization of gas hydrate by visual fixation of the moment of appearance of the solid phase at the interfacial contact «liquid – gas». The design features of the laboratory facility for its implementation have also been developed and substantiated. The technique makes it possible to reduce the duration of the study of one sample by almost an order of magnitude (from several days to 8–10 hours). In addition to the information on the equilibrium parameters of hydrostatic formation, provided by traditional methods of laboratory research, an additional characteristic of the behavior of reservoir systems in non-equilibrium conditions has been obtained, which will help to quickly assess the risks of technogenic hydrate formation. The developed technique is important for systems that, at least, have a memory of hydrate structures. However, the preliminary transfer of a part of the water of the test sample through the gas hydrate form allows estimating the parameters of hydrate formation of any reservoir system.
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Tang, Zhi Yuan, Zan Dong Sun, and Yuan Yin Zhang. "Seismic Studies for Gas Hydrate Characterization in a Marine Case." Advanced Materials Research 468-471 (February 2012): 2759–63. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.2759.
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We combine an integrated study of gas hydrate reservoirs in a marine area from seismic data which collected for oil and gas exploration purpose. This study combines analyses of geology and seismology. First, geological analysis is made using data of material sources, structures and sediments to determine the hydrocarbon formation conditions of gas hydrate. Then seismic amplitude attributes analysis is conducted to predict the potential existence of four types of BSR in this area. Finally, pre-stacked inversion is conducted to predict the potential existence of hydrate and its free gas. Results show that gas hydrate is widely distribute in this area, and the distribution controlled by material source, reservoir space, and geothermal conditions.
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Rees, Emily V. L., Timothy J. Kneafsey, and Yongkoo Seol. "Methane Hydrate Distribution from Prolonged and Repeated Formation in Natural and Compacted Sand Samples: X-Ray CT Observations." Journal of Geological Research 2011 (November 15, 2011): 1–15. http://dx.doi.org/10.1155/2011/791815.
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To study physical properties of methane gas hydrate-bearing sediments, it is necessary to synthesize laboratory samples due to the limited availability of cores from natural deposits. X-ray computed tomography (CT) and other observations have shown gas hydrate to occur in a number of morphologies over a variety of sediment types. To aid in understanding formation and growth patterns of hydrate in sediments, methane hydrate was repeatedly formed in laboratory-packed sand samples and in a natural sediment core from the Mount Elbert Stratigraphic Test Well. CT scanning was performed during hydrate formation and decomposition steps, and periodically while the hydrate samples remained under stable conditions for up to 60 days. The investigation revealed the impact of water saturation on location and morphology of hydrate in both laboratory and natural sediments during repeated hydrate formations. Significant redistribution of hydrate and water in the samples was observed over both the short and long term.
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Sahoo, Sourav K., Laurence J. North, Hector Marín-Moreno, Tim A. Minshull, and Angus I. Best. "Laboratory observations of frequency-dependent ultrasonic P-wave velocity and attenuation during methane hydrate formation in Berea sandstone." Geophysical Journal International 219, no. 1 (2019): 713–23. http://dx.doi.org/10.1093/gji/ggz311.
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SUMMARY Knowledge of the effect of methane hydrate saturation and morphology on elastic wave attenuation could help reduce ambiguity in seafloor hydrate content estimates. These are needed for seafloor resource and geohazard assessment, as well as to improve predictions of greenhouse gas fluxes into the water column. At low hydrate saturations, measuring attenuation can be particularly useful as the seismic velocity of hydrate-bearing sediments is relatively insensitive to hydrate content. Here, we present laboratory ultrasonic (448–782 kHz) measurements of P-wave velocity and attenuation for successive cycles of methane hydrate formation (maximum hydrate saturation of 26 per cent) in Berea sandstone. We observed systematic and repeatable changes in the velocity and attenuation frequency spectra with hydrate saturation. Attenuation generally increases with hydrate saturation, and with measurement frequency at hydrate saturations below 6 per cent. For hydrate saturations greater than 6 per cent, attenuation decreases with frequency. The results support earlier experimental observations of frequency-dependent attenuation peaks at specific hydrate saturations. We used an effective medium rock-physics model which considers attenuation from gas bubble resonance, inertial fluid flow and squirt flow from both fluid inclusions in hydrate and different aspect ratio pores created during hydrate formation. Using this model, we linked the measured attenuation spectral changes to a decrease in coexisting methane gas bubble radius, and creation of different aspect ratio pores during hydrate formation.
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Jiang, Donglei, Yi Yu, Yi Huang, Wenbo Meng, Jianbo Su, and Zhenggang Gong. "Gas Hydrate Formation Risk and Prevention for the Development Wells in the Lingshui Gas Field in South China Sea." Geofluids 2021 (July 30, 2021): 1–13. http://dx.doi.org/10.1155/2021/9122863.
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Hydrate formation risk is an important challenge in the development of deep-water gas field. Considering the characteristics of the Lingshui (LS) gas field in the South China Sea and the difference of well structures, a model for calculating wellbore temperature and pressure in deep-water gas production well is proposed and verified by the field data. Combining the hydrate equilibrium models with varied gas components, the prediction method of hydrate formation region in deep-water gas well in the South China Sea is obtained. The hydrate formation regions under different operating conditions for a deep-water gas well in the South China Sea were given by the proposed model. The results show that no hydrate formation risk exists in the production operation, but the risk exists in the shut-in and testing operations. Meanwhile, the determination of the hydrate inhibitor injection parameters during the testing operation is studied, and the influence of the inhibitors’ injection concentration and pressure on preventing gas hydrates is analyzed. This work provides useful advice for the prediction and prevention of hydrate formation risk in the development of deep-water gas fields, especially in the South China Sea.
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Zuo, Tingna, Ren Wang, Yulin He, et al. "Natural Gas Migration Pathways and Their Influence on Gas Hydrate Enrichment in the Qiongdongnan Basin, South China Sea." Geofluids 2022 (May 27, 2022): 1–19. http://dx.doi.org/10.1155/2022/1954931.
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2D and 3D seismic data and basin simulation were used to investigate the gas hydrate distribution and natural gas migration pathways in the Qiongdongnan Basin (QDNB). Hydrate-related amplitude anomalies and extensive bottom simulating reflectors (BSRs) were mapped within the uppermost part. Based on their seismic reflection characteristics, the three main types of natural gas migration pathways and their distributions in the QDNB were identified through high-resolution seismic data. Basin modeling was carried out to document the migration efficiency of different migration pathways and their effects on hydrate enrichment. The basin modeling results show the following: (1) Diapirs, fault structures, and fractures constitute the three main types of natural gas migration pathways that transport the thermogenic gas from the deep to shallow layers in the QDNB. (2) The three migration pathways impact hydrate enrichment in different ways. Diapirs and faults contribute significantly to hydrate enrichment due to their higher migration efficiency. In comparison, the migration efficiency of the fracture systems is lower, with minimal benefit to hydrate enrichment. (3) The natural gas hydrate in the QDNB is mainly distributed along the diapirs and deep faults and generally scattered around the fracture system. These conclusions indicate that the migration pathways in the QDNB are regionally distributed and are closely related to hydrate accumulation.
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Liang, Jinqiang, Zijian Zhang, Pibo Su, Zhibin Sha, and Shengxiong Yang. "Evaluation of gas hydrate-bearing sediments below the conventional bottom-simulating reflection on the northern slope of the South China Sea." Interpretation 5, no. 3 (2017): SM61—SM74. http://dx.doi.org/10.1190/int-2016-0219.1.
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The continuous bottom-simulating reflection (BSR) is commonly considered to mark the base of gas hydrate stability zone. Below this depth, gas hydrate gives away to free gas or water filling with pore spaces of sediments. We integrated and analyzed seismic data collected in 2008, and logging-while-drilling (LWD) data and coring results acquired by the Fugro Voyager in 2015 in the Shenhu area on the northern slope of the South China Sea. Based on seismic and well-log correlation, a BSR with typical characteristics of gas hydrates and free gas was identified at 237 m, below the mudline (BML). However, LWD data reveal a 63 m thick hydrate layer from 205 to 268 m BML. Increases in resistivity and velocity at 262 m BML indicate that gas hydrate is likely presented below the BSR. The observed pore-water freshening with depth and infrared image of core samples are consistent with geophysical interpretation. Seismic and well interpretations reveal continuous, discontinuous, and pluming BSRs in the Shenhu area. The continuous BSR indicates the base of the methane gas hydrate stability zone, and structure II gas hydrate is likely presented below the BSR. Deep thermogenic fluid locally entrapped within shallow-buried sediments may reinforce gas-hydrate accumulations near the discontinuous and pluming BSRs. We conclude that seismic responses of structure II gas hydrate can be distinct from structure I gas hydrate. Understanding the seismic characterizations of structures I and II will help in the evaluation of gas-hydrate reservoirs and inferring the presence of deep thermogenic reservoirs.
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Nazar, Pedchenko. "Development of methods of operative determination of parameters of repeated hydrate formation in layer systems of gas hydrate deposits." Technology audit and production reserves 3, no. 1(65) (2022): 34–38. https://doi.org/10.15587/2706-5448.2022.259263.
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<em>The object of research is the methods of laboratory setting of the parameters of hydrate formation of well production and the design features of the equipment for its implementation. Methane hydrate is becoming a promising topic for a new energy resource. At the same time, hydrostatic formation is one of the most problematic areas in ensuring the transport of well products, and this primarily concerns the production of gas hydrate deposits. An analysis of the thermobaric parameters of the well production of gas hydrate deposits shows that when they are moved by technological lines, they are close to hydrate equilibrium, but due to the intensity of the process, the system does not have time to reach it. In addition, reservoir system water has a memory of hydrate structures, or a certain amount of gas hydrate solid phase is also present in the flow water. In this regard, a set of laboratory studies was carried out to assess the nature of the behavior of this type of systems during the re-crystallization of gas hydrate and its dissociation. Based on the results of the research, a method for the operational laboratory setting of the parameters of repeated hydrate formation in reservoir systems of gas hydrate deposits was developed. It provides for setting the parameters of mass crystallization of gas hydrate by visual fixation of the moment of appearance of the solid phase at the interfacial contact </em><em>«</em><em>liquid – gas</em><em>»</em><em>. The design features of the laboratory facility for its implementation have also been developed and substantiated. The technique makes it possible to reduce the duration of the study of one sample by almost an order of magnitude (from several days to 8–10</em><em> </em><em>hours). In addition to the information on the equilibrium parameters of hydrostatic formation, provided by traditional methods of laboratory research, an additional characteristic of the behavior of reservoir systems in non-equilibrium conditions has been obtained, which will help to quickly assess the risks of technogenic hydrate formation. The developed technique is important for systems that, at least, have a memory of hydrate structures. However, the preliminary transfer of a part of the water of the test sample through the gas hydrate form allows estimating the parameters of hydrate formation of any reservoir system.</em>
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Shi, Shiyuan, Linsen Zhan, Wenjiu Cai, Ran Yang, and Hailong Lu. "Bottom-Simulating Reflectors (BSRs) in Gas Hydrate Systems: A Comprehensive Review." Journal of Marine Science and Engineering 13, no. 6 (2025): 1137. https://doi.org/10.3390/jmse13061137.
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The bottom-simulating reflector (BSR) serves as an important seismic indicator for identifying gas hydrate-bearing sediments. This review synthesizes global BSR observations and demonstrates that spatial relationships among BSRs, free gas, and gas hydrates frequently deviate from one-to-one correspondence. Moreover, our analysis reveals that more than 35% of global BSRs occur shallower than the bases of gas hydrate stability zones, especially in deepwater regions, suggesting that the BSRs more accurately represent the interface between the gas hydrate occurrence zone and the underlying free gas zone. BSR morphology is influenced by geological settings, sediment properties, and seismic acquisition parameters. We find that ~70–80% of BSRs occur in fine-grained, grain-displacive sediments with hydrate lenses/nodules, while coarse-grained pore-filling sediments host <20%. BSR interpretation remains challenging due to limitations in traditional P-wave seismic profiles and conventional amplitude versus offset (AVO) analysis, which hinder accurate fluid identification. To address these gaps, future research should focus on frequency-dependent AVO inversion based on viscoelastic theory, multicomponent full-waveform inversion, improved anisotropy assessment, and quantitative links between rock microstructure and elastic properties. These innovations will shift BSR research from static feature mapping to dynamic process analysis, enhancing hydrate detection and our understanding of hydrate–environment interactions.
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Pandey, Jyoti, and Nicolas Solms. "Hydrate Stability and Methane Recovery from Gas Hydrate through CH4–CO2 Replacement in Different Mass Transfer Scenarios." Energies 12, no. 12 (2019): 2309. http://dx.doi.org/10.3390/en12122309.
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CH4–CO2 replacement is a carbon-negative, safer gas production technique to produce methane gas from natural gas hydrate reservoirs by injecting pure CO2 or other gas mixtures containing CO2. Laboratory-scale experiments show that this technique produces low methane volume and has a slow replacement rate due to the mass transfer barrier created due to impermeable CO2 hydrate layer formation, thus making the process commercially unattractive. This mass-transfer barrier can be reduced through pressure reduction techniques and chemical techniques; however, very few studies have focused on depressurization-assisted and chemical-assisted CH4–CO2 replacement to lower mass-transfer barriers and there are many unknowns. In this work, we qualitatively and quantitatively investigated the effect of the pressure reduction and presence of a hydrate promoter on mixed hydrate stability, CH4 recovery, and risk of water production during CH4–CO2 exchange. Exchange experiments were carried out using the 500 ppm sodium dodecyl sulfate (SDS) solution inside a high-pressure stirred reactor. Our results indicated that mixed hydrate stability and methane recovery depends on the degree of pressure reduction, type, and composition of injected gas. Final selection between CO2 and CO2 + N2 gas depends on the tradeoff between mixed hydrate stability pressure and methane recovery. Hydrate morphology studies suggest that production of water during the CH4–CO2 exchange is a stochastic phenomenon that is dependent on many parameters.