Article
Energy & Fuels
Boris Bukhanov, Evgeny Chuvilin, Aliya Mukhametdinova, Natalia Sokolova, Mikhail Afonin, Vladimir Istomin
Summary: This study uses nuclear magnetic resonance relaxometry to estimate the content of residual pore water in gas hydrate reservoirs. The results show that the presence of gas pressure and cooling decreases the content of residual pore water. It is also found that samples with higher clay content contain more residual pore water.
Article
Energy & Fuels
Xin Wang, Fang Wang, Xinle Yang, Weizhong Li, Yongchen Song
Summary: The exploitation of natural gas hydrates faces challenges such as low gas production efficiency and sustainability. The presence of methane in water and the formation of ice contribute to these challenges. A model is proposed to study the effects of mass transfer limitation and ice formation/melting on hydrate dissociation. Numerical simulation and experimental data validate the reliability of the proposed model, revealing the complex nature of methane hydrate dissociation in the presence of ice. The presence of ice weakens the mass transfer limitation effect.
Article
Thermodynamics
Yajin Zhang, Bo Dong, Ping Wang, Feifan Geng, Lunxiang Zhang, Yan Qin, Cong Chen, Weizhong Li
Summary: A coupled lattice Boltzmann model is proposed to study the gas hydrate dissociation and ice evolution in microporous media. The reliability of this model is verified by simulating the dissociation of xenon hydrate and the freezing of water droplets. The initial temperature plays a significant role in methane hydrate dissociation and ice evolution. The research provides insight into the effect of ice evolution on methane hydrate dissociation in practical applications.
Article
Engineering, Environmental
Yan Xie, Yu-Jie Zhu, Tao Zheng, Qing Yuan, Chang-Yu Sun, Lan-Ying Yang, Guang-Jin Chen
Summary: Utilizing multi-defective ice to construct porous CO2 hydrate can improve the efficiency of CH4-CO2 hydrate replacement, providing a new method for CH4 recovery and CO2 sequestration. Experimental results showed that the replacement efficiency at 272.15 K was significantly higher than at 268.15 K, confirming the feasibility of the replacement concept.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Thermodynamics
Shuang Dong, Mingjun Yang, Lei Zhang, Jia-nan Zheng, Yongchen Song
Summary: This study investigates the thermodynamic evolution of methane hydrate-bearing deposits during long depressurization. Five experiments with different methane yields were conducted to simulate the process. The results show that the rates of depressurization and hydrate dissociation increase linearly with increasing methane yield. Icing occurs when the pressure reaches a certain level and accelerates the dissociation of hydrates. Different exploitation stages exhibit different thermodynamic responses due to the combination of various non-equilibrium processes. The findings provide insights into the complex coupling mechanism of phase change and heat and mass transfer in methane hydrate exploitation.
Article
Biochemistry & Molecular Biology
Alexei Finkelstein, Sergiy O. Garbuzynskiy, Bogdan S. Melnik
Summary: The classical nucleation theory states that the presence of ice-binding surfaces is required for ice nucleation at temperatures above approximately -30 degrees C. Experiments show that the ice nucleation temperature ranges from -8 degrees C to -15 degrees C for buffer and water in plastic test tubes. The addition of ice-initiating substances (such as conventional AgI or CuO) results in ice formation at temperatures ranging from -3 degrees C to -7 degrees C, while the ice-nucleating bacterium, Pseudomonas syringae, causes ice formation at temperatures from -1 degrees C to -2 degrees C. The action of the tested ice-initiating agents is inhibited by the addition of an antifreeze protein.
Article
Energy & Fuels
Xuebing Zhou, Qian Zhang, Zhen Long, Deqing Liang
Summary: The study found that the addition of KHIs significantly reduced the self-preservation effect of CH4 hydrates and increased the dissociation rate of hydrates. PVP-K90 and PVCap had different mechanisms of action, with the former embedded in small ice crystals inhibiting the connections of plate-like ice crystals, and the latter inducing dendritic growth of CH4 hydrates, leading to an increase in specific surface area.
Article
Chemistry, Multidisciplinary
Liwen Li, Xiao Wang, Youguo Yan, Joseph S. Francisco, Jun Zhang, Xiao Cheng Zeng, Jie Zhong
Summary: This study investigates the nucleation process of natural gas hydrates at different degrees of supercooling using molecular dynamics simulations. The concept of a transition layer is proposed to explain the distinct nucleation phenomena observed at different supercoolings.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Kun Luo, Yidi Shen, Jun Li, Qi An
Summary: The stability mechanism of methane hydrate under pressure has been elucidated through molecular dynamics simulations using a quantum mechanics-derived machine-learning force field. It has been found that the decomposition behavior of methane hydrate is regulated by the stability of water cages, with the most stable methane hydrate occurring at 2 kbar. Deviation from the optimal water molecule distance due to too low or too high pressure leads to rapid deconstruction of water cages and promotes the decomposition of methane hydrates. These findings provide molecular insights into pressure-dependent decomposition of methane hydrates and have implications for the stability of other gas hydrates.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Construction & Building Technology
Ming-Liang Yan, Jian Xie, Jia-Bao Yan
Summary: This paper experimentally studied the size effect, freezing point, melting time, and durability of plain salt-water ice (PSI) and PVA reinforced salt-water ice (PRSI) to promote its application as a new construction material in the Arctic and cold regions. It was found that PSI exhibited a size effect while PRSI was not sensitive to varying diameters. Additionally, adding PVA powder in ice increased its freezing rate and prolonged the melting time, proving the effectiveness of this reinforcing method. Considering the workability and durability, PRSI provides an alternative for engineering infrastructures and temporary constructions in cold regions.
JOURNAL OF BUILDING ENGINEERING
(2023)
Article
Thermodynamics
Mingjun Yang, Shuang Dong, Jie Zhao, Jia-nan Zheng, Zheyuan Liu, Yongchen Song
Summary: By adjusting the reservoir temperature and production pressure, the production process of methane hydrate and the behavior of ice can be controlled, thereby affecting the dissociation rate of hydrates. Higher production pressures can prevent the formation of ice, and both the melting of ice and the dissociation of hydrates are influenced by heat supply.
Article
Chemistry, Physical
Gaurav Vishwakarma, Jyotirmoy Ghosh, Thalappil Pradeep
Summary: Reflection absorption infrared spectroscopic investigations of multilayer films of acetonitrile (ACN) and water in an ultrahigh vacuum under isothermal conditions showed the emergence of cubic (ice I-c) and hexagonal (ice I-h) ices depending on the composition of the film. The experiments revealed that ice I-h can form at temperatures as low as 125K and its crystallization kinetics and activation energy were evaluated using the Avrami equation.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Mohammad Tariq, Mario R. C. Soromenho, Manuel M. Pineiro, Martin Perez-Rodriguez, Dalip Kumar, Ana Rodriguez, Francisco J. Deive, Jose M. S. S. Esperanca
Summary: In this study, the phase equilibria of CO2 hydrates in H2O, D2O, and their binary mixtures were investigated. The results showed that there is a difference in the equilibrium line of CO2 hydrates formed in H2O and D2O, but the hydrate dissociation enthalpies were similar. The study also revealed the influence of isotopic effect on CO2 hydrate formation and dissociation, which may have implications for separation and purification processes.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Energy & Fuels
Dehuan Yang, Rongtao Yan, Feng Cheng, Di Lu, Changfu Wei, Huihui Tian
Summary: The low-field NMR method was used to investigate the impact of various experimental conditions on the hydration number during methane hydrate dissociation. It was found that the NMR signal peak value of water was not affected by sediment dry density, gas pressure, and salt concentration, but was significantly influenced by temperature. A relationship among NMR signal peak value, substance content, pressure, and temperature was established to estimate the hydration number of pore hydrates. The experimental results showed that the hydration number of methane hydrates remained practically unchanged during dissociation in fine-grained sediments, and was minimally influenced by experimental conditions.
Article
Engineering, Chemical
S. Y. Misyura, I. G. Donskoy
Summary: Despite the widespread interest in gas hydrates, there are still many fundamental problems that need to be solved, particularly in the storage and transportation aspect. This study presents approximate models to describe the dissociation of methane gas hydrate and offers ways to reduce the dissociation rate and increase the shelf life of gas hydrates. The findings can contribute to the improvement of technologies related to both artificial and natural gas hydrates.
Article
Geochemistry & Geophysics
Ryu Uemura, Kosuke Masaka, Yoshinori Iizuka, Motohiro Hirabayashi, Hitoshi Matsui, Risei Matsumoto, Miki Uemura, Koji Fujita, Hideaki Motoyama
Summary: Chemical proxy data from ice cores can provide information about environmental changes, and the flux of sulfate onto the ice in Antarctica has remained relatively stable over glacial-interglacial cycles. By studying the sulfur isotopic record in the Antarctic Dome Fuji ice core, it was found that during the Last Glacial Maximum (LGM), the sulfur isotope ratio was depleted and negatively correlated with terrestrial contributions. These results suggest that salts in deserts should be considered a terrestrial source of Antarctic sulfate during the LGM.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Chemistry, Physical
Yusuke Jin, Masato Kida, Jiro Nagao
Summary: This study reports the conformation selectivity of cyclohexanol in a clathrate hydrate and the effect of hydrogen bonds on lattice shrinkage. The results show that cyclohexanol prefers the equatorial conformation over the axial conformation and that the hydrogen bond between cyclohexanol and the water framework causes a reduction in the lattice constant.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Environmental Sciences
Chihiro Miyamoto, Yoshinori Iizuka, Sumito Matoba, Shohei Hattori, Yoshio Takahashi
Summary: By examining calcium species in the aerosol particles trapped in an ice core, this study found that gypsum content was higher in recent layers compared to older layers, while calcite fraction showed the opposite trend. The increased gypsum content was consistent with the increase of sulfur dioxide emission in China. The results indicate that the calcium species in dust trapped in the ice core can serve as a good indicator of the long-term variation of sulfur dioxide emission in the region.
ATMOSPHERIC ENVIRONMENT
(2022)
Article
Energy & Fuels
Yusuke Jin, Masato Kida, Jiro Nagao
Summary: In this study, a novel hydrate former with the ability to act as a structure II former and a thermodynamic inhibitor is reported. Thiazole, an aromatic five-ringed molecule, forms an sII hydrate crystal with small CH4 and CO2 molecules. The thiazole molecule exhibits guest-host interactions with water frameworks through hydrogen bonding. This molecule, however, cannot form an sII hydrate with the C2H6 molecule and instead functions as a thermodynamic inhibitor for the sI C2H6 hydrate.
Article
Geography, Physical
Kaoru Kawakami, Yoshinori Iizuka, Sumito Matoba, Teruo Aoki, Takuto Ando
Summary: This study investigates the characteristics of inclusions in ice layers of the Greenland ice sheet using microscopy and spectroscopy. The results reveal different shapes and chemical compositions of the inclusions, which have implications for estimating future sea level rise and studying past and future ice sheet melting behavior.
JOURNAL OF GLACIOLOGY
(2023)
Article
Thermodynamics
Yusuke Jin, Motoi Oshima, Jiro Nagao
Summary: The size of structure-H clathrate hydrates (sH hydrates) depends on the size of large molecule guest substances (LMGSs). The c-axis in an sH hydrate structure is sensitive to the longest molecular length of the LMGSs. Four new LMGSs for structure-H hydrates containing CH4 were reported: iodocyclopentane (ICP), chlorocycloheptane (ClCHP), bromocycloheptane (BrCHP), and trans-1,4-dichlorocyclohexane (t14DClCH). The temperature shifts of the four LMGS systems from the pure CH4-water system increased in the following order: ICP & SIM < BrCHP (3.7 K) < ClCHP (4.7 K) < t14DClCH (5.1 K).
JOURNAL OF CHEMICAL AND ENGINEERING DATA
(2023)
Article
Engineering, Ocean
Hiroyuki Oyama, Tomoya Ogino, Toru Sato, Hisato Yasuda, Jiro Nagao, Norio Tenma
Summary: It has been discovered that mud flocs and methane hydrate coexist in sediment layers off the coast of Japan. There is concern that the flow of pure water from the dissociation of methane hydrate may break down the mud flocs, leading to sand problems in production wells. This study examined the characteristics of the flocs by observing samples collected from natural cores and testing their mechanical stability in distilled water flow. The flocs were found to mainly consist of silt and were stable under certain flow rates, but decomposed into silt and clay particles when subjected to pressure, suggesting they could be a source of fine particles as underground stress conditions change.
MARINE GEORESOURCES & GEOTECHNOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Christo Buizert, Sarah Shackleton, Jeffrey P. Severinghaus, William H. G. Roberts, Alan Seltzer, Bernhard Bereiter, Kenji Kawamura, Daniel Baggenstos, Anais J. Orsi, Ikumi Oyabu, Benjamin Birner, Jacob D. Morgan, Edward J. Brook, David M. Etheridge, David Thornton, Nancy Bertler, Rebecca L. Pyne, Robert Mulvaney, Ellen Mosley-Thompson, Peter D. Neff, Vasilii V. Petrenko
Summary: Researchers have developed a new ice core gas-phase proxy to study large-scale atmospheric circulation through synoptic pressure variability. The proxy, Kr-86(xs), reflects the average synoptic pressure changes over several years, but cannot capture individual short-term weather events. The validation of Kr-86(xs) using Antarctic and Greenland ice cores shows a strong spatial correlation with time-averaged synoptic variability. However, caution is needed in interpreting the proxy due to uncertainties in corrections and limited understanding of firn physics.
CLIMATE OF THE PAST
(2023)
Article
Energy & Fuels
Yusuke Jin, Masato Kida, Jiro Nagao
Summary: In this study, a novel hydrate former was discovered to act as a structure II (sII) former and thermodynamic inhibitor. Thiazole, an aromatic five-ringed molecule with two heteroatoms, was found to form sII hydrate crystals with small CH4 and CO2 molecules. The guest-host interactions between thiazole and the water frameworks were analyzed, and it was found that thiazole functions as a thermodynamic inhibitor for the structure I (sI) C2H6 hydrate.
Article
Geosciences, Multidisciplinary
Ikumi Oyabu, Kenji Kawamura, Shuji Fujita, Ryo Inoue, Hideaki Motoyama, Kotaro Fukui, Motohiro Hirabayashi, Yu Hoshina, Naoyuki Kurita, Fumio Nakazawa, Hiroshi Ohno, Konosuke Sugiura, Toshitaka Suzuki, Shun Tsutaki, Ayako Abe-Ouchi, Masashi Niwano, Frederic Parrenin, Fuyuki Saito, Masakazu Yoshimori
Summary: We reconstructed the surface mass balance (SMB) around Dome Fuji in Antarctica over the past 5000 years using data from ice cores and snow pits. The reconstructed SMB records showed spatial patterns influenced by the location of the ice divides, proximity to the ocean, and wind direction. The stacked record exhibited a long-term decreasing trend, possibly due to surface cooling and sea ice expansion. The variations in the SMB were consistent with previous records in East Antarctica.
CLIMATE OF THE PAST
(2023)
Article
Environmental Sciences
Yutaka Kurosaki, Sumito Matoba, Yoshinori Iizuka, Koji Fujita, Rigen Shimada
Summary: A study suggests that declines in Arctic sea ice may result in increased emissions of dimethyl sulfide, which can influence marine cloud formation. Researchers utilized a 55-year ice core record from the southeast Greenland Ice Sheet to examine temporal variations in dimethyl sulfide emissions, finding a correlation between fluxes of methane sulfonic acid (an oxidation product of dimethyl sulfide) and chlorophyll-a concentration in the Irminger Sea during the spring. Summertime fluxes of methane sulfonic acid were significantly higher between 2002-2014 compared to 1972-2001, likely attributable to earlier sea ice retreat and increased chlorophyll-a concentration in coastal waters.
COMMUNICATIONS EARTH & ENVIRONMENT
(2022)
Article
Geography, Physical
Shun Tsutaki, Shuji Fujita, Kenji Kawamura, Ayako Abe-Ouchi, Kotaro Fukui, Hideaki Motoyama, Yu Hoshina, Fumio Nakazawa, Takashi Obase, Hiroshi Ohno, Ikumi Oyabu, Fuyuki Saito, Konosuke Sugiura, Toshitaka Suzuki
Summary: The retrieval of continuous ice core records of more than 1 Myr is a significant challenge in paleoclimatology. Ground-based ice radar surveys were conducted over Dome Fuji in the East Antarctic plateau to identify suitable sites for drilling. The newly generated high-spatial-resolution ice thickness map, along with other analyses, provides important constraints for identifying possible drilling locations. Comparisons with earlier bed maps highlight the need for validation with in situ observations.
Article
Geography, Physical
Tomotaka Saruya, Shuji Fujita, Yoshinori Iizuka, Atsushi Miyamoto, Hiroshi Ohno, Akira Hori, Wataru Shigeyama, Motohiro Hirabayashi, Kumiko Goto-Azuma
Summary: This study investigates the crystal orientation fabric (COF) in the upper 80% of the Dome Fuji Station ice core in East Antarctica using dielectric anisotropy (Delta epsilon) data. The results show that Delta epsilon values increase with depth, fluctuating over short distances and decreasing significantly at depths corresponding to major glacial to interglacial transitions.
Article
Geography, Physical
Giyoon Lee, Jinho Ahn, Hyeontae Ju, Florian Ritterbusch, Ikumi Oyabu, Christo Buizert, Songyi Kim, Jangil Moon, Sambit Ghosh, Kenji Kawamura, Zheng-Tian Lu, Sangbum Hong, Chang Hee Han, Soon Do Hur, Wei Jiang, Guo-Min Yang
Summary: This study reports on a surface transect of ice from the Larsen Blue-Ice Area (BIA) in northern Victoria Land, East Antarctica. The ice layers exhibit a monotonic increase in age along the ice flow direction downstream, while the upstream ice shows potential repetition of ages on tens of meters. Stable water isotopes and components of occluded air are analyzed to reconstruct the climate and atmospheric greenhouse gas compositions. The findings suggest a large deglacial warming and increased snow accumulation. This study demonstrates the importance of blue-ice areas in obtaining high-quality paleoclimate records, despite the complexities involved.
Article
Environmental Sciences
Taku Umezawa, Satoshi Sugawara, Kenji Kawamura, Ikumi Oyabu, Stephen J. Andrews, Takuya Saito, Shuji Aoki, Takakiyo Nakazawa
Summary: This study reconstructed the history of atmospheric CH4 using Arctic firn air data sets. Despite uncertainties, the reconstructions are consistent with existing observations. The atmospheric CH4 scenario used currently is considered the best choice, but further verification is needed.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2022)
