• Title, Summary, Keyword: gas hydrate

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Study of Producing Natural Gas From Gas Hydrate With Industrial Flue Gas (산업용 배기가스를 이용한 가스 하이드레이트로부터의 천연가스 생산 연구)

  • Seo, Yu-Taek;Kang, Seong-Pil;Lee, Jae-Goo;Cha, Min-Jun;Lee, Huen
    • 한국신재생에너지학회:학술대회논문집
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    • pp.188-191
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    • 2008
  • There have been many methods for producing natural gas from gas hydrate reservoirs in permafrost and sea floor sediments. It is well knownthat the depressurization should be a best option for Class 1 gas hydrate deposit, which is composed of tow layers: hydrate bearing layer and an underlying free gas. However many of gas hydrate reservoirs in sea floor sediments are classified as Class 2 that is composed of gas hydrate layer and mobile water, and Class 3 that is a single gas hydrate layer. The most appropriate production methods among the present methods such as thermal stimulation, inhibitor injection, and controlled oxidation are still under development with considering the gas hydrate reservoir characteristics. In East Sea of Korea, it is presumed that the thick fractured shale deposits could be Class 2 or 3, which is similar to the gas hydrate discovered offshore India. Therefore it is needed to evaluate the possible production methods for economic production of natural gas from gas hydrate reservoir. Here we would like to present the production of natural gas from gas hydrate deposit in East Sea with industrial flue gases from steel company, refineries, and other sources. The existing industrial complex in Gyeongbuk province is not far from gas hydrate reservoir of East Sea, thus the carbon dioxide in flue gas could be used to replace methane in gas hydrate. This approach is attractive due to the suggestion of natural gas productionby use of industrial flue gas, which contribute to the reduction of carbon dioxide emission in industrial complex. As a feasibility study, we did the NMR experiments to study the replacement reaction of carbon dioxide with methane in gas hydrate cages. The in-situ NMR measurement suggeststhat 42% of methane in hydrate cages have been replaced by carbon dioxide and nitrogen in preliminary test. Further studies are presented to evaluate the replacement ratio of methane hydrate at corresponding flue gas concentration.

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Gas trasport and Gas hydrate distribution characteristics of Southern Hydrate Ridge: Results from ODP Leg 204

  • Lee, Young-Joo;Ryu, Byong-Jae;Kim, Ji-Hoon;Lee, Sang-Il
    • 한국신재생에너지학회:학술대회논문집
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    • pp.407-409
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    • 2006
  • Geochemical analyses carried out on samples collected from cores on and near the southern smit of Hydrate Ridge have advanced understanding by providing a clear contrast of the two major modes of marine gas hydrate occurrence. High concentrations (15%-40% of pore space) of gas hydrate occurring at shallow depths (0-40 mbsf) on and near the southern summit are fed by gas migrating from depths of as much as 2km within the accretionary prism. This gas carries a characteristic minor component of C2-C5 thermogenic hydrocarbons that enable tracing of migration pathways and may stabilize the occurrence of some structure II gas hydrate. A structure II wet gas hydrate that is stable to greater depths and temperatures than structure I methane hydrate may account for the deeper, faint second bottom simulating reflection (BSR2) that occurs on the seaward side of the ridge. The wet gas is migrating In an ash/turbidite layer that intersects the base of gas hydrate stability on the seaward side of and directly beneath the southern summit of Hydrate Ridge. The high gas saturation (>65%) of the pore space within this layer could create a two-phase (gas + solid) system that would enable free gas to move vertically upward through the gas hydrate stability zone. Away from the summit of the ridge there is no apparent influx of the gas seeping from depth and sediments are characterized by the normal sequence of early diagenetic processes involving anaerobic oxidation of sedimentary organic matter, initially linked to the reduction of sulfate and later continued by means of carbonate reduction leading to the formation of microbial methane.

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Geotechnical properties of gas hydrate bearing sediments (가스 하이드레이트 부존 퇴적토의 지반공학적 물성)

  • Kim, Hak-Sung;Cho, Gye-Chun;Lee, Joo-Young
    • 한국신재생에너지학회:학술대회논문집
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    • pp.151-151
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    • 2011
  • Large amounts of natural gas, mainly methane, in the form of hydrates are stored on continental margins. When gas hydrates are dissociated by any environmental trigger, generation of excess pore pressure due to released free gas may cause sediment deformation and weakening. Hence, damage on offshore structures or submarine landslide can occur by gas hydrate dissociation. Therefore, geotechnical stability of gas hydrate bearing sediments is in need to be securely assessed. However, geotechnical characteristics of gas hydrates bearing sediments including small-strain elastic moduli have been poorly identified. Synthesizing gas hydrate in natural seabed sediment specimen, which is mainly composed of silty-to-clayey soils, has been hardly attempted due to their low permeability. Moreover, it has been known that hydrate loci in pore spaces and heterogeneity of hydrate growth in specimen scale play a critical role in determining physical properties of hydrate bearing sediments. In the presented study, we synthesized gas hydrate containing sediments in an instrumented oedometric cell. Geotechnical and geophysical properties of gas hydrate bearing sediments including compressibility, small-strain elastic moduli, elastic wave, and electrical resistivity are determined by wave-based techniques during loading and unloading processes. Significant changes in volume change, elastic wave, and electrical resistivity have been observed during formation and dissociation of gas hydrate. Experimental results and analyses reveal that geotechnical properties of gas hydrates bearing sediments are highly governed by hydrate saturation, effective stress, void ratio, and soil types as well as morphological feature of hydrate formation in sediments.

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Natural gas hydrate occurrence and detection in the Sea of Okhotsk

  • Jin Young-Keun;CHAOS Scientific Party CHAOS Scientific Party
    • 한국신재생에너지학회:학술대회논문집
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    • pp.47-49
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    • 2006
  • The Sea of Okhotsk is the unique area providing the highest methane production rate of the northern hemisphere. The area of focused fluid venting offshore the NE Sakhalin continental slope was investigated during the CHAOS (Hydro-Carbon Hydrate Accumulations in the Okhotsk Sea) expeditions onboard of RV "Akademik Lavrentyev" In 2003, 2005 and 2006. The International Research Project CHAOS (Russia-Korea-Japan) aimed at the study of gas hydrate formation processes associated with the fluid venting in the Sea of Okhotsk. Several new gas hydrate accumulations were discovered during the cruise. Hydrate-associated structures have been named as KOPRI, VNIIOKeangeologia, POI and KIT (the names of cruise participant institutes) Some of hydrate-bearing cores contain big amount of gas hydrates: massive gas hydrate layers (up to 35cm thick) were recovered. The shallowest submarine gas hydrate accumulations in the world (at the depth less then 400m) were discovered during the cruise.

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A Comparative Experiment on the Hydrate Structures I and II for the Solid Transportation of Natural Gas (천연가스 고체화수송을 위한 하이드레이트 구조 I과 II에 대한 비교실험)

  • 김남진;김종보
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.8
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    • pp.674-682
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    • 2003
  • Natural gas hydrate typically contains 85 wt.% water and 15 wt.% natural gas, and commonly belongs to cubic structure I and II. Also, 1m$^3$ hydrate of natural gas can be decomposed to 200 m$^3$ natural gas at standard condition. If this characteristic of hydrate is reversely utilized, natural gas is fixed into water and produced to hydrate. Therefore the hydrate is great as a means to transport and store natural gas. So, the tests were performed on the formation of natural gas hydrate is governed by the pressure, temperature, gas composition etc. The results show that the equilibrium pressure of structure II is approximately 65% lower and the solubility is about 3 times higher than structure I. Also if the subcoolings of structure I and structure II are more than 9 K and 11 K respectively, the hydrates are rapidly formed.

[ $CO_2$ ] Sequestration on Various Structures of Natural Gas Hydrate Layer for Effective Recovery of $CH_4$ Gas

  • Park, Young-June;Choi, Suk-Jeong;Shin, Kyu-Chul;Seol, Ji-Woong;Lee, Hu-En
    • 한국신재생에너지학회:학술대회논문집
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    • pp.410-411
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    • 2006
  • On the continental margins and in permafrost regions, natural gas, which has been expected to replace petroleum energy, exists In solid hydrate farm. World hydrate reserves Including natural gas are estimated at about twice as much as the energy contained In total fossil fuel reserves. Because of its vast quantities, the efficient recovery of natural gas from natural gas hydrate becomes the most important factor on evaluating the economic feasibility in the sense of commercialization. It has been noted that carbon dioxide, one of the well-known green house gases, possibly can be stored in the ocean floor as a carbon dioxide hydrate. If the natural gas hydrate could be converted into carbon dioxide hydrate, natural gas hydrate deposits would serve as energy sources as well as carbon dioxide storage sites in the deep ocean sediments. In this study, we first attempted to examine the real swapping phenomenon occurring between guest molecules and various structures of gas hydrate through spectroscopic identification such as NMR spectroscopy.

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The Economic Aspect of Gas Hydrate Development (경제성 측면에서의 가스하이드레이트 개발 가치)

  • Kim, Hwa-Young;Lee, Dong-Jun;Heo, Eun-Nyeong
    • New & Renewable Energy
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    • v.4 no.2
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    • pp.61-67
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    • 2008
  • The price to import natural gas continues to rise, as well as the rate of its domestic consumption. This research examined the economic feasibility of domestically developing and producing gas hydrate to substitute imported natural gas. Today, the industry still lacks the technology to commercially produce gas hydrate. However, if the gas hydrate is able to be commercially produced domestically and replace imported natural gas, the annual economic benefit for the Republic of Korea would be 211 - 833 USD/ton. Gas hydrate is rated as a high value investment by the gas industry since the potential annual profit can reach over 150USD/ton. The commercial value of gas hydrate development will increase as long as the natural gas market continues to expand and its consumption increase remains steady. With further development of technology, one can anticipate an even higher expected return on the investment.

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Investigation on the Self-preservation Effect of Natural Gas Hydrates (천연가스 하이드레이트의 자기보존 효과 연구)

  • Lee, Jong-Won;Lee, Ju Dong
    • 한국신재생에너지학회:학술대회논문집
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    • pp.123.2-123.2
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    • 2011
  • Self-preservation effect was identified by means of macroscopic dissociation experiments after keeping natural gas hydrate samples at 258 K for 15 days. The hydrate samples were formed using synthetic natural gas hydrate whose compositions are 90% $CH_4$, 7% $C_2H_6$, and 3% $C_3H_8$. In addition, during the formation, heavy hydrocarbons of propane and ethane are found to occupy hydrate cages in a more favorable way than methane so as to change the gas composition after hydrate formation. Experimental results obtained in this study can provide useful information on applications of natural gas hydrate for storing or transporting natural gas in the form of solid hydrate.

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Excess Pore Water Pressure Calculation Methods due to Gas Hydrate Dissociation (가스 하이드레이트의 해리로 발생하는 간극수압의 계산방법)

  • Park, Sung-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.888-892
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    • 2008
  • If gas hydrate dissociates due to natural and/or human activities, it generates large amount of gas and water. Upon gas hydrate dissociation, a generated pore water pressure between soil particles increases and results in the loss of an effective stress and degradation of soil stiffness and strength. In order to predict the generated excess pore water pressure due to gas hydrate dissociation, two methods based on small hydrate concept (SHC) and large hydrate concept (LHC) are proposed. An excess pore water pressure generated by the gas hydrate dissociation in the Storegga Slide was calculated using two proposed methods.

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Methane hydrate formation Using Carbon Nano Tubes (탄소나노튜브를 이용한 메탄 하이드레이트 형성)

  • Park, Sung-Seek;Seo, Hyang-Min;Kim, Nam-Jin
    • 한국신재생에너지학회:학술대회논문집
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    • pp.549-552
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    • 2009
  • Methane hydrate is crystalline ice-like compounds which formed methane gas enters within water molecules composed cavity at specially temperature and pressure condition, and water molecule and each other from physically-bond. $1m^3$ hydrate of pure methane can be decomposed to the maximum of $172m^3$ at standard condition. If these characteristics of hydrate are reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18~24% less than the liquefied transportation. However, when methane hydrate is formed artificially, the amount of consumed gas is relatively low due to a slow reaction rate between water and methane gas. In this study, for the better hydrate reaction rate, there is make nano fluid using ultrasonic dispersion of carbon nano tube. and then, Experiment with hydrate formation by nano fluid and methane gas reaction. The results show that when the carbon nano tubes of 0.004 wt% was added to pure water, the amount of consumed gas was about 300% higher than that in pure water and the hydrate formation time decreased.

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