• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.519-523
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• 2007

Gas(or methane) hydrates are solid solutions when water molecules are linked through hydrogen bonding and create host lattice cavities that can enclose a large variety of guest gas molecules. The natural gas hydrate crystal may exist at low temperature above the normal freezing point of water and high pressure greater than about 30 bars. A lot of quantities of natural gas hydrates exists in the earth and many production schemes are being studied. In the present investigation, depressurization method was considered to predict the production of gas and the simulation of the two phase flow - gas and water - in porous media is being carried out. The simulation show about the fluid flow in porous media have a variety of applications in industry. Results provide the appearance of gas and water production, the pressure profile, the saturation of gas/ water/ hydrates profiles and the location of the pressure front.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.615-617
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• 2005

[ $^{13}C$ ] NMR spectra were obtained for pure $CH_4$ hydrate in order to identify hydrate structure and cage occupancy of guest molecule. The NMR technique can provide both qualitative and quantitative hydrate characteristics. The moles of methane captured into pure $CH_4$ hydrate per mole of water were found to be similar to the full occupancy value. The overall results drawn from this study can be usefully applied to storage and transportation of natural gas.

• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.24-30
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• 2004

Gas hydrate formation process is studied in this paper. Natural gas was introduced into both pure water and water added anionic surfactant(promotor) at 276.65 K and 6 MPa. Gas hydrate nuclei was easily generated by instantaneous agitation. Gas hydrate film was formed on the interface of water and gas. The very thin film which was instantly covered the surface of the water, followed by generation of the clear film layer. Whiskery crystal of gas hydrate was created more actively in the water added naionic surfactant than in the pure water. Whiskery hydrate formed in the pure water looks like short and thick thread colony while the one shoes long and thin thread colony in the water added promoter.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.597-599
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• 2007

Studies on the hydrocarbons in shallow sediments of the East Sea of Korea have been carried out by the Korea Institute of Geoscience and Mineral Resources (KIGAM) since 2000. 4946 L-km of 2D multichannel reflection seismic data, 3250 L-km of high-resolution Chirp profiles and 16 selected piston cores were analyzed to determine the presence of hydrocarbons in shallow sediments of the western deep-water Ulleung Basin. The seismic data show a number of blanking zones that probably reflect widespread fluid and gas venting. The blanking zones are often associated with velocity pull-up structures. These upwelling structures are interpreted to be the result of high-velocity natural gas hydrate. There are also several bottom-simulating reflectors that are associated with free gas and probably overlying gas hydrate. Numerous pockmarks were also observed in the Chirp profiles. They are seafloor depressions caused by the removal of near-seafloor soft sediments by escaping of fluid and gas. In piston cores, cracks generally oriented parallel to bedding suggest significant gas content some of which may have been contained in gas hydrate in situ.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.192-195
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• 2008

Conventional gas deposits consist of pressurized gas held in porous and permeable reservoir rocks and its recovery takes place where the natural pressure of the gas reservoir forces gas to the surface. But gas hydrate is a crystalline solid, its prospects require reservoir rock properties approprate porosity, permeability with mapping of temperature and pressure conditions to define the hydrate stability zone. In this study, we have carried out to investigate the dissociation characteristics of methane hydrates and the productivities of dissociated gas and water with depressurization scheme. Also, it has been conducted the flowing behavior of the dissociated gas and water in porous rock and the efficiency of the production.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.102-107
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• 2006

In Japan, research and development were undertaken on gas hydrate-side industrial processes associated with power generation system connections that may particularly be necessary to develop gas hydrated technology-based industrial systems. In so doing, data and engineering technologies useful n formulating guidelines on design of practical process were accumulated. In addition, basic research into theoretical evidence were carried out to promote and support the development of technological elements for those processes. In basic research designed to promote and support the research and development of elemental technologies, microanalyses were conducted to understand the decomposition mechanism of mixed gas hydrate. Moreover, measurement technologies that can be applied in industrial processes, such as numerical analyses and concentration measurement, were examined. Japan has developed a highly efficient gas hydrate formation process using micro-bubbles with a tubular reactor. Higher formation rate over conventional systems has been obtained by the process. As mentioned above, the technical problems were clarified and the economics were studied from a view point of the NGH technology in this study. The results can be applied for utilization and must contribute to popularization of gas hydrate production.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.511-514
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• 2007

Gas hydrate has a unique property that can store a large volume of gas in water as a solid form. Even though investigations for natural gas storage technology have been carried out for several decades, there are still a lot of unsolved problems due to complex formation process, low formation speed, high energy consumption and so on. So, lots of experiments were conducted to overcome these weaknesses and to develop artificial NGH formation technology applicable to industrial-scale storage and commercial transport. In this study, some series of experiments were performed to analyze both stirred and unstirred system especially about the influences of several gas hydrate formation factors such as agitation speed, system temperature, SDS concentration, etc. As a result, optimum range of SDS concentration and temperature that could enhance the storage capacity and shorten the formation time were found. And it is obviously presented that SDS such a kind of surfactant promotes gas hydrate formation dramatically and the quantity of stored gas are proportional to agitation speed in stirred system.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.415-418
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• 2006

In Japan, research and development were undertaken on gas hydrate-side industrial processes associated with power generation system connections that may particularly be necessary to develop gas hydrated technology-based industrial systems. In so doing, data and engineering technologies useful n formulating guidelines on design of practical process were accumulated. In addition, basic research into theoretical evidence were carried out to promote and support the development of technological elements for those processes. In basic research designed to promote and support the research and development of elemental technologies microanalyses were conducted to understand the decomposition mechanism of mixed gas hydrate. Moreover, measurement technologies that can be applied in industrial processes, such as numerical analyses and concentration ion measurement, were examined. Japan has developed a highly efficient gas hydrate formation process using micro-bubbles with a tubular reactor. Higher formation rate over conventional systems has been obtained by the process. As mentioned above, the technical problems were clarified and the economics were studied from a view point of the NGH technology in this study. The results can be applied for utilization and must contribute to popularization of gas hydrate production.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.769-775
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• 2011

Methane hydrate is formed by physical binding between water molecules and methane gas, which is captured in the cavities of water molecules under the specific temperature and pressure. $1m^3$ hydrate of pure methane can be decomposed to the methane gas of $172m^3$ and water of $0.8m^3$ at standard condition. Therefore, there are a lot of practical applications such as separation processes, natural gas storage transportation and carbon dioxide sequestration. For the industrial utilization of hydrate, it is very important to rapidly manufacture hydrate. So in this study, hydrate formation was experimented by adding THF and oxidized carbon nanotubes in distilled water, respectively. The results show that when the oxidized carbon nanofluids of 0.03 wt% was, the amount of gas consumed during the formation of methane hydrate was higher than that in the THF aqueous solution. Also, the oxidized carbon nanofluids decreased the hydrate formation time to a greater extent than the THF aqueous solution at the same subcooling temperature.

• Economic and Environmental Geology
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• v.38 no.2 s.171
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• pp.165-176
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• 2005

Natural gas in deep sediment may occur in three phases based on the physical and chemical conditions. If the concentration of gas in pore water is less than the solubility, gas is dissolved. If the concentration of gas is greater than its solubility (water is saturated or supersaturated with gas), gas occurs as a fee gas below the gas hydrate stability Lone (GHSZ) and is present as solid hydrate within the GHSZ. The knowledge of gas concentration in deep sediment appears critical to determine the phase of natural gases and to understand the formation and distribution of gas hydrate. However, reliable data on gas concentration are usually available only from the upper section of marine sediment by the headspace gas technique, which is widely used for sampling of gases from the sediments. The headspace gas technique represents only a fraction of gases present in situ because sediments release most of the gases during recovery and sampling. The PCS (Pressure Core Sampler) is a downhole tool developed to recover a nominal $1{\cal}m$ long, $4.32{\cal}cm$ diameter core containing $1,465cm^3$ of sediment, pore water and gas at in situ pressure up to 68.9 MPa. During Leg 204, the PCS was deployed at 6 Sites. In situ methane gas concentration and distribution of gas hydrate was measured by using PCS tool. Characteristics of methane concentration and distribution is different from site to site. Distribution of gas hydrate in the study area is closely related to characteristics of in situ gas concentration measured by PCS.