• Title, Summary, Keyword: gas hydrate

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Observation of Gas Hydrate Formation by View Cell (View cell에 의한 가스 하이드레이트 생성 관찰)

  • Cho Byoung-Hak;Lee Young-Chul;Mo Yung-Gi;Baek Young-Soon
    • Journal of the Korean Institute of Gas
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    • v.8 no.3
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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.

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Prestack depth migration for gas hydrate seismic data set (가스 하이드레이트 탄성파 자료에 대한 중합전 심도 구조보정)

  • Hien, Doan Huy;Jang, Seong-Hyung;Kim, Yong-Wan;Suh, Sang-Yong
    • 한국신재생에너지학회:학술대회논문집
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    • pp.564-568
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    • 2007
  • Gas hydrate has been attractive topic for two dedicates because it may cause the global warming, ocean hazards associated with the instability of marine slope due to the gas hydrate release as well as high potential of future energy resources. The study on gas hydrate in Ulleung basin has been performed since 1999 to explore the potential and distribution of gas hydrate offshore Korea. The numerous multi channel seismic data have been acquired and processed by Korea Institute of Geosciences and Mineral Resources (KIGAM). The results showed clearly the gas hydrate indicators such as pull up structure, bottom simulating reflector (BSR), seismic blanking zone. The prestack depth migration has been considered as fast and accurate technique to image the subsurface. In this paper, we will present both the conventional seismic data processing and apply Kirchhoff prestack depth migration for gas hydrate data set. The results will be applied for core sample collections and for proposal more detail 2D with long offset or 3D seismic exploration.

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Recent advances in natural gas hydrate carriers for gas transportation - A review and conceptual design

  • Kim, Kipyoung;Kim, Youtaek;Kang, Hokeun
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.5
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    • pp.589-601
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    • 2014
  • Natural gas hydrate (NGH) is emerging as a new eco-friendly source of energy to replace fossil fuels in the 21st century. It is well known that the Natural Gas Hydrate contains large amount of natural gas about 170 times as much as its volume and it is easy to be stored and transported safely at about $-20^{\circ}C$ under atmospheric pressure due to so called "self-preservation effect". The option of gas transport by gas hydrate pellets carrier has been investigated and developed in various industry and academy. The natural gas hydrate pellet carrier is on major link in a potential gas hydrate process chain, starting with the extraction of natural gas from the reservoir, followed by the production of hydrate pellets and the transportation to an onshore terminal for further processing or marketing. In recent years, Korean project team supported by Korean Government has been working on the development of NGH total systems including novel NGH carrier since 2011. In order to increase the knowledge on the NGH pellet carrier developed and to understand the major hazards that could have significant impact on the safety of the vessel, this paper presents and evaluates the pros and cons of cargo holds, loading and unloading systems through the analysis of current patent technology. Based on the proven and well-known technologies as well as potential measures to mitigate sintering and minimize mechanical stress on the hydrate pellet in the self-preservation state, this study presents the conceptual and basic design for NGH carrier.

Seismic Pre-processing and AVO analysis for understanding the gas-hydrate structure (가스 하이드레이트 부존층의 구조 파악을 위한 탄성파 전산처리 및 AVO 분석)

  • Chung Bu-Heung
    • 한국신재생에너지학회:학술대회논문집
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    • pp.634-637
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    • 2005
  • Multichannel seismic data acquired in Ulleung Basin of East Sea for gas hydrate exploration. The seismic sections of this area show strong BSR(bottom simulating reflections) associated with methane hydrate occurrence in deep marine sediments. Very limited information is available from deep sea drilling as the risk of heating and destabilizing the initial hydrate conditions during the processing of drilling is considerably high. Not so many advanced status of gas hydrate exploration in Korea, the most of information of gas hydrate characteristics and properties are inferred from seismic reflection data. In this study, The AVO analysis using the long offset seismic data acquired in Ulleung Basin used to explain the characteristics and structure of gas hydrate. It is used primarily P-wave velocity accessible from seismic data. To make a good quality of AVO analysis input data, seismic preprocessing including 'true gain correction', 'source signature deconvolution', twice velocity analysis and some kinds of multiple rejection and enhancing the signal to noise ratio processes is carried out very carefully. The results of AVO analysis, the eight kinds of AVO attributes are estimated basically and some others of AVO attributes are evaluated for interpretation of AVO analysis additionally. The impedance variation at the boundary of gas hydrate and free gas is estimated for investing the BSR characteristics and properties. The complex analysis is performed also to verifying the amplitude variation and phase shift occurrence at BSR. Type III AVO anomaly appearance at saturated free gas area is detected on BSR. It can be an important evidence of gas hydrate deposition upper the BSR.

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Study on Gas Hydrates for the Solid Transportation of Natural Gas

  • Kim, Nam-Jin;Kim, Chong-Bo
    • Journal of Mechanical Science and Technology
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    • v.18 no.4
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    • pp.699-708
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    • 2004
  • Natural gas hydrate typically contains 85 wt.% water and 15 wt.% natural gas, and commonly belongs to cubic structure I and II. When referred to standard conditions, 1 ㎤ solid hydrate contains up to 200㎥ of natural gas depending on pressure and temperature. Such the large volume of natural gas hydrate can be utilized to store and transport a large quantity of natural gas in a stable condition. In the present investigation, experiments were carried out for the formation of natural gas hydrate governed by pressure, temperature, gas compositions, etc. The results show that the equilibrium pressure of structure II is approximately 65% lower and the solubility is approximately 3 times higher than structure I. It is also found that for the sub-cooling of structure I and II of more than 9 and 11 K respectively, the hydrates are rapidly being formed. It is noted that utilizing nozzles for spraying water in the form of droplets into the natural gas dramatically reduces the hydrate formation time and increases its solubility at the same time.

Quantification of the risk for hydrate formation during cool down in a dispersed oil-water system

  • Kwak, Gye-Hoon;Lee, Kun-Hong;Lee, Bo Ram;Sum, Amadeu K.
    • Korean Journal of Chemical Engineering
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    • v.34 no.7
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    • pp.2043-2048
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    • 2017
  • Gas hydrates are considered a nuisance in the flow assurance of oil and gas production since they can block the flowlines, consequently leading to significant losses in production. Hydrate avoidance has been the traditional approach, but recently, hydrate management is gaining acceptance because the practice of hydrate avoidance has become more and more challenging. For better management of hydrate formation, we investigated the risk of hydrate formation based on the subcooling range in which hydrates form by associating low, medium, and high probability of formation for a gas+oil+water system. The results are based on batch experiments which were performed in an autoclave cell using a mixture gas ($CH_4:C_3H_8=91.9:8.1mol%$), total liquid volume (200 ml), mineral oil, watercut (30%), and mixing speed (300 rpm). From the measurements of survival curves showing the minimum subcooling required before hydrate can form and hydrate conversion rates for the initial 20 minutes, we developed a risk map for hydrate formation.

An experimental study on the factors to improve the formation performance of gas hydrate (가스하이드레이트 제조성능 향상을 위한 영향인자 검토 연구)

  • Shin, Chang-Hoon;Kim, Yu-Na;Kwon, Ok-Bae;Park, Seung-Su;Han, Jeong-Min;Lee, Jeong-Hwan
    • Proceedings of the KSME Conference
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    • pp.2989-2994
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    • 2007
  • Gas hydrates are ice-like crystalline compounds that form under low temperature and elevated pressure conditions. Although hydrate formation can pose serious flow-assurance problems in the gas pipelines or facilities, gas hydrates present a novel means for natural gas storage and transportation with potential applications in a wide variety of areas. An important property of hydrates that makes them attractive for use in gas storage and transportation is their very high gas-to-solid ratio. In addition to the high gas content, gas hydrates are remarkably stable. The main barrier to development of gas hydrate technology is the lack of an effective method to mass produce gas hydrate in solid form. The first objective of this study is investigating the characteristics of gas hydrate formation related to several factors such as pressure, temperature, water-to-storage volume ratio, concentration of SDS, heat transfer and whether stirred or not respectively. And the second objective is clarifying the relation between the formation efficiency and each factor in order to find the proper way or direction to improve the formation performance.

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Seismic modeling consider of inhomogeneous gas hydrate layer (불균질 가스하이드레이트 층을 고려한 탄성파 모델링)

  • Kim, Young-Wan;Jang, Seong-Hyung;Yoon, Wang-Joong;Suh, Sang-Yong
    • 한국신재생에너지학회:학술대회논문집
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    • pp.489-492
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    • 2007
  • The P-wave velocity at the formation which contains gas hydrate varies very wide upon gas hydrate existence. These features on seismic shot gather can not be simulated normally by numerical modeling of homogeneous medium so that we need that of random inhomogeneous medium instead. We, in this study generated random inhomogeneous medium using gaussian ACF, exponential ACF and von Karman ACF and that we supposed the random inhomogeneous medium be gas hydrate formation to execute numeric modeling. The modeling result shows the typical effect by scattering caused by random hydrate formation as is observed from seismic shot gather where hydrate exist.

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A Comparative Study on the Formation of Methane Hydrate Using Natural Zeolite and Synthetic Zeolite 5A (천연 제올라이트와 합성 제올라이트 5A를 이용한 메탄 하이드레이트의 생성에 대한 비교 연구)

  • Park, Sung-Seek;Park, Yun-Beom;Kim, Nam-Jin
    • New & Renewable Energy
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    • v.8 no.2
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    • pp.24-32
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    • 2012
  • Natural gas hydrates have a high potential as the 21st century new energy resource, because it have a large amount of deposits in many deep-water and permafrost regions of the world widely. Natural gas hydrate is formed by physical binding between water molecule and gas mainly composed of methane, which is captured in the cavities of water molecules under the specific temperature and pressure. $1m^3$ methane hydrate 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 methane hydrate, it is very important to rapidly manufacture hydrate. However, when methane hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. So in this study, hydrate formation was experimented by adding natural zeolite and Synthetic zeolite 5A in distilled water, respectively. The results show that when the Synthetic zeolite 5A of 0.01 wt% was, the amount of gas consumed during the formation of methane hydrate was higher than that in the natural zeolite. Also, the natural zeolite and Synthetic zeolite 5A decreased the hydrate formation time to a greater extent than the distilled water at the same subcooling temperature.

Formation and Dissociation Processes of Gas Hydrate Composed of Methane and Carbon Dioxide below Freezing

  • Hachikubo, Akihiro;Yamada, Koutarou;Miura, Taku;Hyakutake, Kinji;Abe, Kiyoshi;Shoji, Hitoshi
    • Ocean and Polar Research
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    • v.26 no.3
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    • pp.515-521
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    • 2004
  • The processes of formation and dissociation of gas hydrates were investigated by monitoring pressure and temperature variations in a pressure cell in order to understand the kinetic behavior of gas hydrate and the controlling factors fur the phase transition of gas hydrate below freezing. Gas hydrates were made kom guest gases ($CH_4,\;CO_2$, and their mixed-gas) and fine ice powder. We found that formation and dissociation speeds of gas hydrates were not controlled by temperature and pressure conditions alone. The results of this study suggested that pressure levels at the formation of mixed-gas hydrate determine the transient equilibrium pressure itself.