The Experts below are selected from a list of 4227 Experts worldwide ranked by ideXlab platform
Mingjun Yang - One of the best experts on this subject based on the ideXlab platform.
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Effect of multiphase flow on natural Gas Hydrate Production in marine sediment
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Huiru Sun, Bingbing Chen, Mingjun YangAbstract:Abstract Natural Gas Hydrates (NGHs), regarded as an alternative future energy source. Currently, tests for Hydrate exploitation from marine sediment have been performed in the Nankai Trough of Japan and the Shenhu area of the South China Sea. Hydrate exploitation is influenced by water-Gas flow in the sediment, and considering the huge seawater reserves in Hydrate accumulation areas, an experiment of seawater-Gas flow was performed to dissociate Hydrate. The effects of seawater-Gas flow rates and initial Hydrate saturation on methane Hydrate (MH) Production were analyzed. The results showed that seawater-Gas flow efficiently promotes Hydrate dissociation and inhibits Hydrate reformation. Moreover, there was a faster heat and mass transfer with increasing seawater flow rates and decreasing Gas flow rates, which enhanced the average MH dissociation rate. In addition, the variation time of the flow channel increased with higher initial Hydrate saturation. Additionally, seawater-Gas flow promotes MH dissociation stronger than deionized water-Gas flow.
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The enhancement effect of water-Gas two-phase flow on depressurization process: Important for Gas Hydrate Production
Applied Energy, 2020Co-Authors: Huiru Sun, Bingbing Chen, Mingjun Yang, Guojun Zhao, Yuechao Zhao, Yongchen SongAbstract:Abstract Depressurization is one of the most efficient methods in the Production testing of natural Gas Hydrates. However, problems such as Hydrate reformation, ice generation and insufficient dissociation driving force in the later period of depressurization adversely affect the Gas Production. It has been confirmed that controlling the flowrate ratio of a water-Gas two-phase flow can help enhance the Hydrate dissociation. However, the effect of the water-Gas flowrate ratio on the Hydrate dissociation behaviors during depressurization is unclear. In this study, three dissociation modes involving a combination of water-Gas flow and depressurization were examined: mode 1 (concurrent start of depressurization and water-Gas flow), mode 2 (depressurization is first used to dissociate the Hydrate, and the water-Gas flow is initiated after 15 min), and mode 3 (depressurization is first used, and the water-Gas flow is initiated after 30 min). The feasibility of water-Gas flow to accelerate Hydrate dissociation and mitigate ice generation was confirmed during the depressurization process. In all the modes, the higher water-Gas flowrate ratio and lower dissociation pressure significantly increased the energy recovery rate and decreased the energy input. Additionally, the water-Gas flow, especially that with a higher flowrate ratio, effectively accelerated the elimination of the dark-zone (mixture of ice and Hydrate) by providing continuous heat transfer. Mode 1 corresponded to the highest energy recovery rate, lowest energy input and most rapid disappearance of the dark-zone under the same experimental conditions. Therefore, mode 1 was regarded as the most efficient mode to dissociate Hydrate in an actual Hydrate Production.
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Visualization study on the promotion of natural Gas Hydrate Production by water flow erosion
Fuel, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Pengfei Wang, Dayong WangAbstract:Abstract Natural Gas Hydrates (NGHs) are a new, clean, and effective energy source with great potential for exploitation. The efficient exploitation of NGHs has been a focus of research worldwide. Water migration in Hydrate sediments is an important parameter influencing NGH exploitation. However, there is still little research in terms of visualization studies on the variation of Hydrate distribution during the water flow process in Hydrate-bearing sediment. Such variation of Hydrate distribution and the influence of water migration on methane Hydrate (MH) dissociation with different backpressures and water flow rates were systematically and visually analyzed in this study, where the influence of temperature and pressure variation on MH dissociation was completely eliminated. The results showed that the chemical potential difference between the Hydrate phase and the aqueous phase caused MH dissociation during the water flow process and that the rate of MH dissociation increased with decreasing backpressure and increasing water flow rate. When the rate of MH dissociation is low, there will be a longer time for the flow channel to appear, vary, and disappear. Based on this conclusion, a new method of water flow erosion to improve NGH exploitation is proposed in this study.
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Visualization study on the promotion of depressurization and water flow erosion for Gas Hydrate Production
Energy Procedia, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Dayong Wang, Lanlan Jiang, Yongchen SongAbstract:Abstract Natural Gas Hydrates (NGHs) are a potential energy source for the future. The efficient exploitation of NGHs has been a hot topic of worldwide research. At present, the depressurization is considered as the most effective method for NGHs exploitation. However, the lacking of Hydrate decomposition driving force in depressurization anaphase and the ice generation phenomenon haven’t been solved effectively. The combination method of depressurization with water flow erosion was carried out in this study. The experimental results indicated that driving force for MH decomposition will be not enough when the exploitation backpressure was higher than 2.4 MPa. The combination of depressurization with water flow erosion will efficiently solve the lacking of drive force for depressurization in anaphase and shorten the time of Hydrate exploitation. The existence of chemical potential difference accelerated the Hydrate decomposition.
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Effects of pressure and sea water flow on natural Gas Hydrate Production characteristics in marine sediment
Applied Energy, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Hang Zhou, Dayong WangAbstract:Abstract Natural Gas Hydrates (NGHs) widely exist in continental permafrost or marine sediment, and with a carbon quantity twice that of all fossil fuels combined, they are a potential energy source for the future. The efficient exploitation of NGHs has been a popular topic of research worldwide. Currently, existing NGH exploitation methods each present characteristic defect. In this study, by combining visualization studies with sea water phase migration, which is a crucial factor influencing NGH exploitation, the method of water flow erosion was utilized to enhance the driving force of methane Hydrate (MH) dissociation. The influence of seawater migration on MH dissociation was systematically and visually studied by controlling different back pressures and seawater flow rates. There was no observed influence of temperature or pressure variation during the MH dissociation process. The results showed that the chemical potential difference between the Hydrate phase and aqueous phase caused MH dissociation during the seawater flow process and that the rate of MH dissociation increased with decreasing backpressure and increasing water flow rate. It can be predicted that there will be no MH dissociation or time variations of absolute MH dissociation when the water flow rate is sufficiently low or high. The water migration, water phase permeability and MH dissociation strongly interacted with one another. This study combined a visualization study with theoretical analysis and first found that the gradient decrease of pressure difference lead to the increase of permeability during different stages of the seawater flow process.
Bingbing Chen - One of the best experts on this subject based on the ideXlab platform.
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Effect of multiphase flow on natural Gas Hydrate Production in marine sediment
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Huiru Sun, Bingbing Chen, Mingjun YangAbstract:Abstract Natural Gas Hydrates (NGHs), regarded as an alternative future energy source. Currently, tests for Hydrate exploitation from marine sediment have been performed in the Nankai Trough of Japan and the Shenhu area of the South China Sea. Hydrate exploitation is influenced by water-Gas flow in the sediment, and considering the huge seawater reserves in Hydrate accumulation areas, an experiment of seawater-Gas flow was performed to dissociate Hydrate. The effects of seawater-Gas flow rates and initial Hydrate saturation on methane Hydrate (MH) Production were analyzed. The results showed that seawater-Gas flow efficiently promotes Hydrate dissociation and inhibits Hydrate reformation. Moreover, there was a faster heat and mass transfer with increasing seawater flow rates and decreasing Gas flow rates, which enhanced the average MH dissociation rate. In addition, the variation time of the flow channel increased with higher initial Hydrate saturation. Additionally, seawater-Gas flow promotes MH dissociation stronger than deionized water-Gas flow.
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The enhancement effect of water-Gas two-phase flow on depressurization process: Important for Gas Hydrate Production
Applied Energy, 2020Co-Authors: Huiru Sun, Bingbing Chen, Mingjun Yang, Guojun Zhao, Yuechao Zhao, Yongchen SongAbstract:Abstract Depressurization is one of the most efficient methods in the Production testing of natural Gas Hydrates. However, problems such as Hydrate reformation, ice generation and insufficient dissociation driving force in the later period of depressurization adversely affect the Gas Production. It has been confirmed that controlling the flowrate ratio of a water-Gas two-phase flow can help enhance the Hydrate dissociation. However, the effect of the water-Gas flowrate ratio on the Hydrate dissociation behaviors during depressurization is unclear. In this study, three dissociation modes involving a combination of water-Gas flow and depressurization were examined: mode 1 (concurrent start of depressurization and water-Gas flow), mode 2 (depressurization is first used to dissociate the Hydrate, and the water-Gas flow is initiated after 15 min), and mode 3 (depressurization is first used, and the water-Gas flow is initiated after 30 min). The feasibility of water-Gas flow to accelerate Hydrate dissociation and mitigate ice generation was confirmed during the depressurization process. In all the modes, the higher water-Gas flowrate ratio and lower dissociation pressure significantly increased the energy recovery rate and decreased the energy input. Additionally, the water-Gas flow, especially that with a higher flowrate ratio, effectively accelerated the elimination of the dark-zone (mixture of ice and Hydrate) by providing continuous heat transfer. Mode 1 corresponded to the highest energy recovery rate, lowest energy input and most rapid disappearance of the dark-zone under the same experimental conditions. Therefore, mode 1 was regarded as the most efficient mode to dissociate Hydrate in an actual Hydrate Production.
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Visualization study on the promotion of natural Gas Hydrate Production by water flow erosion
Fuel, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Pengfei Wang, Dayong WangAbstract:Abstract Natural Gas Hydrates (NGHs) are a new, clean, and effective energy source with great potential for exploitation. The efficient exploitation of NGHs has been a focus of research worldwide. Water migration in Hydrate sediments is an important parameter influencing NGH exploitation. However, there is still little research in terms of visualization studies on the variation of Hydrate distribution during the water flow process in Hydrate-bearing sediment. Such variation of Hydrate distribution and the influence of water migration on methane Hydrate (MH) dissociation with different backpressures and water flow rates were systematically and visually analyzed in this study, where the influence of temperature and pressure variation on MH dissociation was completely eliminated. The results showed that the chemical potential difference between the Hydrate phase and the aqueous phase caused MH dissociation during the water flow process and that the rate of MH dissociation increased with decreasing backpressure and increasing water flow rate. When the rate of MH dissociation is low, there will be a longer time for the flow channel to appear, vary, and disappear. Based on this conclusion, a new method of water flow erosion to improve NGH exploitation is proposed in this study.
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Visualization study on the promotion of depressurization and water flow erosion for Gas Hydrate Production
Energy Procedia, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Dayong Wang, Lanlan Jiang, Yongchen SongAbstract:Abstract Natural Gas Hydrates (NGHs) are a potential energy source for the future. The efficient exploitation of NGHs has been a hot topic of worldwide research. At present, the depressurization is considered as the most effective method for NGHs exploitation. However, the lacking of Hydrate decomposition driving force in depressurization anaphase and the ice generation phenomenon haven’t been solved effectively. The combination method of depressurization with water flow erosion was carried out in this study. The experimental results indicated that driving force for MH decomposition will be not enough when the exploitation backpressure was higher than 2.4 MPa. The combination of depressurization with water flow erosion will efficiently solve the lacking of drive force for depressurization in anaphase and shorten the time of Hydrate exploitation. The existence of chemical potential difference accelerated the Hydrate decomposition.
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Effects of pressure and sea water flow on natural Gas Hydrate Production characteristics in marine sediment
Applied Energy, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Hang Zhou, Dayong WangAbstract:Abstract Natural Gas Hydrates (NGHs) widely exist in continental permafrost or marine sediment, and with a carbon quantity twice that of all fossil fuels combined, they are a potential energy source for the future. The efficient exploitation of NGHs has been a popular topic of research worldwide. Currently, existing NGH exploitation methods each present characteristic defect. In this study, by combining visualization studies with sea water phase migration, which is a crucial factor influencing NGH exploitation, the method of water flow erosion was utilized to enhance the driving force of methane Hydrate (MH) dissociation. The influence of seawater migration on MH dissociation was systematically and visually studied by controlling different back pressures and seawater flow rates. There was no observed influence of temperature or pressure variation during the MH dissociation process. The results showed that the chemical potential difference between the Hydrate phase and aqueous phase caused MH dissociation during the seawater flow process and that the rate of MH dissociation increased with decreasing backpressure and increasing water flow rate. It can be predicted that there will be no MH dissociation or time variations of absolute MH dissociation when the water flow rate is sufficiently low or high. The water migration, water phase permeability and MH dissociation strongly interacted with one another. This study combined a visualization study with theoretical analysis and first found that the gradient decrease of pressure difference lead to the increase of permeability during different stages of the seawater flow process.
Huiru Sun - One of the best experts on this subject based on the ideXlab platform.
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Effect of multiphase flow on natural Gas Hydrate Production in marine sediment
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Huiru Sun, Bingbing Chen, Mingjun YangAbstract:Abstract Natural Gas Hydrates (NGHs), regarded as an alternative future energy source. Currently, tests for Hydrate exploitation from marine sediment have been performed in the Nankai Trough of Japan and the Shenhu area of the South China Sea. Hydrate exploitation is influenced by water-Gas flow in the sediment, and considering the huge seawater reserves in Hydrate accumulation areas, an experiment of seawater-Gas flow was performed to dissociate Hydrate. The effects of seawater-Gas flow rates and initial Hydrate saturation on methane Hydrate (MH) Production were analyzed. The results showed that seawater-Gas flow efficiently promotes Hydrate dissociation and inhibits Hydrate reformation. Moreover, there was a faster heat and mass transfer with increasing seawater flow rates and decreasing Gas flow rates, which enhanced the average MH dissociation rate. In addition, the variation time of the flow channel increased with higher initial Hydrate saturation. Additionally, seawater-Gas flow promotes MH dissociation stronger than deionized water-Gas flow.
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The enhancement effect of water-Gas two-phase flow on depressurization process: Important for Gas Hydrate Production
Applied Energy, 2020Co-Authors: Huiru Sun, Bingbing Chen, Mingjun Yang, Guojun Zhao, Yuechao Zhao, Yongchen SongAbstract:Abstract Depressurization is one of the most efficient methods in the Production testing of natural Gas Hydrates. However, problems such as Hydrate reformation, ice generation and insufficient dissociation driving force in the later period of depressurization adversely affect the Gas Production. It has been confirmed that controlling the flowrate ratio of a water-Gas two-phase flow can help enhance the Hydrate dissociation. However, the effect of the water-Gas flowrate ratio on the Hydrate dissociation behaviors during depressurization is unclear. In this study, three dissociation modes involving a combination of water-Gas flow and depressurization were examined: mode 1 (concurrent start of depressurization and water-Gas flow), mode 2 (depressurization is first used to dissociate the Hydrate, and the water-Gas flow is initiated after 15 min), and mode 3 (depressurization is first used, and the water-Gas flow is initiated after 30 min). The feasibility of water-Gas flow to accelerate Hydrate dissociation and mitigate ice generation was confirmed during the depressurization process. In all the modes, the higher water-Gas flowrate ratio and lower dissociation pressure significantly increased the energy recovery rate and decreased the energy input. Additionally, the water-Gas flow, especially that with a higher flowrate ratio, effectively accelerated the elimination of the dark-zone (mixture of ice and Hydrate) by providing continuous heat transfer. Mode 1 corresponded to the highest energy recovery rate, lowest energy input and most rapid disappearance of the dark-zone under the same experimental conditions. Therefore, mode 1 was regarded as the most efficient mode to dissociate Hydrate in an actual Hydrate Production.
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Visualization study on the promotion of natural Gas Hydrate Production by water flow erosion
Fuel, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Pengfei Wang, Dayong WangAbstract:Abstract Natural Gas Hydrates (NGHs) are a new, clean, and effective energy source with great potential for exploitation. The efficient exploitation of NGHs has been a focus of research worldwide. Water migration in Hydrate sediments is an important parameter influencing NGH exploitation. However, there is still little research in terms of visualization studies on the variation of Hydrate distribution during the water flow process in Hydrate-bearing sediment. Such variation of Hydrate distribution and the influence of water migration on methane Hydrate (MH) dissociation with different backpressures and water flow rates were systematically and visually analyzed in this study, where the influence of temperature and pressure variation on MH dissociation was completely eliminated. The results showed that the chemical potential difference between the Hydrate phase and the aqueous phase caused MH dissociation during the water flow process and that the rate of MH dissociation increased with decreasing backpressure and increasing water flow rate. When the rate of MH dissociation is low, there will be a longer time for the flow channel to appear, vary, and disappear. Based on this conclusion, a new method of water flow erosion to improve NGH exploitation is proposed in this study.
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Visualization study on the promotion of depressurization and water flow erosion for Gas Hydrate Production
Energy Procedia, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Dayong Wang, Lanlan Jiang, Yongchen SongAbstract:Abstract Natural Gas Hydrates (NGHs) are a potential energy source for the future. The efficient exploitation of NGHs has been a hot topic of worldwide research. At present, the depressurization is considered as the most effective method for NGHs exploitation. However, the lacking of Hydrate decomposition driving force in depressurization anaphase and the ice generation phenomenon haven’t been solved effectively. The combination method of depressurization with water flow erosion was carried out in this study. The experimental results indicated that driving force for MH decomposition will be not enough when the exploitation backpressure was higher than 2.4 MPa. The combination of depressurization with water flow erosion will efficiently solve the lacking of drive force for depressurization in anaphase and shorten the time of Hydrate exploitation. The existence of chemical potential difference accelerated the Hydrate decomposition.
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Effects of pressure and sea water flow on natural Gas Hydrate Production characteristics in marine sediment
Applied Energy, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Hang Zhou, Dayong WangAbstract:Abstract Natural Gas Hydrates (NGHs) widely exist in continental permafrost or marine sediment, and with a carbon quantity twice that of all fossil fuels combined, they are a potential energy source for the future. The efficient exploitation of NGHs has been a popular topic of research worldwide. Currently, existing NGH exploitation methods each present characteristic defect. In this study, by combining visualization studies with sea water phase migration, which is a crucial factor influencing NGH exploitation, the method of water flow erosion was utilized to enhance the driving force of methane Hydrate (MH) dissociation. The influence of seawater migration on MH dissociation was systematically and visually studied by controlling different back pressures and seawater flow rates. There was no observed influence of temperature or pressure variation during the MH dissociation process. The results showed that the chemical potential difference between the Hydrate phase and aqueous phase caused MH dissociation during the seawater flow process and that the rate of MH dissociation increased with decreasing backpressure and increasing water flow rate. It can be predicted that there will be no MH dissociation or time variations of absolute MH dissociation when the water flow rate is sufficiently low or high. The water migration, water phase permeability and MH dissociation strongly interacted with one another. This study combined a visualization study with theoretical analysis and first found that the gradient decrease of pressure difference lead to the increase of permeability during different stages of the seawater flow process.
Dayong Wang - One of the best experts on this subject based on the ideXlab platform.
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Visualization study on the promotion of natural Gas Hydrate Production by water flow erosion
Fuel, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Pengfei Wang, Dayong WangAbstract:Abstract Natural Gas Hydrates (NGHs) are a new, clean, and effective energy source with great potential for exploitation. The efficient exploitation of NGHs has been a focus of research worldwide. Water migration in Hydrate sediments is an important parameter influencing NGH exploitation. However, there is still little research in terms of visualization studies on the variation of Hydrate distribution during the water flow process in Hydrate-bearing sediment. Such variation of Hydrate distribution and the influence of water migration on methane Hydrate (MH) dissociation with different backpressures and water flow rates were systematically and visually analyzed in this study, where the influence of temperature and pressure variation on MH dissociation was completely eliminated. The results showed that the chemical potential difference between the Hydrate phase and the aqueous phase caused MH dissociation during the water flow process and that the rate of MH dissociation increased with decreasing backpressure and increasing water flow rate. When the rate of MH dissociation is low, there will be a longer time for the flow channel to appear, vary, and disappear. Based on this conclusion, a new method of water flow erosion to improve NGH exploitation is proposed in this study.
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Visualization study on the promotion of depressurization and water flow erosion for Gas Hydrate Production
Energy Procedia, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Dayong Wang, Lanlan Jiang, Yongchen SongAbstract:Abstract Natural Gas Hydrates (NGHs) are a potential energy source for the future. The efficient exploitation of NGHs has been a hot topic of worldwide research. At present, the depressurization is considered as the most effective method for NGHs exploitation. However, the lacking of Hydrate decomposition driving force in depressurization anaphase and the ice generation phenomenon haven’t been solved effectively. The combination method of depressurization with water flow erosion was carried out in this study. The experimental results indicated that driving force for MH decomposition will be not enough when the exploitation backpressure was higher than 2.4 MPa. The combination of depressurization with water flow erosion will efficiently solve the lacking of drive force for depressurization in anaphase and shorten the time of Hydrate exploitation. The existence of chemical potential difference accelerated the Hydrate decomposition.
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Effects of pressure and sea water flow on natural Gas Hydrate Production characteristics in marine sediment
Applied Energy, 2019Co-Authors: Bingbing Chen, Huiru Sun, Mingjun Yang, Hang Zhou, Dayong WangAbstract:Abstract Natural Gas Hydrates (NGHs) widely exist in continental permafrost or marine sediment, and with a carbon quantity twice that of all fossil fuels combined, they are a potential energy source for the future. The efficient exploitation of NGHs has been a popular topic of research worldwide. Currently, existing NGH exploitation methods each present characteristic defect. In this study, by combining visualization studies with sea water phase migration, which is a crucial factor influencing NGH exploitation, the method of water flow erosion was utilized to enhance the driving force of methane Hydrate (MH) dissociation. The influence of seawater migration on MH dissociation was systematically and visually studied by controlling different back pressures and seawater flow rates. There was no observed influence of temperature or pressure variation during the MH dissociation process. The results showed that the chemical potential difference between the Hydrate phase and aqueous phase caused MH dissociation during the seawater flow process and that the rate of MH dissociation increased with decreasing backpressure and increasing water flow rate. It can be predicted that there will be no MH dissociation or time variations of absolute MH dissociation when the water flow rate is sufficiently low or high. The water migration, water phase permeability and MH dissociation strongly interacted with one another. This study combined a visualization study with theoretical analysis and first found that the gradient decrease of pressure difference lead to the increase of permeability during different stages of the seawater flow process.
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Experimental investigation of natural Gas Hydrate Production characteristics via novel combination modes of depressurization with water flow erosion
Fuel, 2019Co-Authors: Bingbing Chen, Huiru Sun, Dayong Wang, Mingjun YangAbstract:Abstract Depressurization is considered the most efficient method for natural Gas Hydrates (NGHs) exploitation. However, ice formation, Hydrate reformation, and insufficient decomposition driving forces in the later stages of depressurization are the main issues to be solved. In this study, a more effective combination of depressurization with water flow erosion for the Production of NGHs was investigated to promote efficient exploitation of methane Hydrate (MH) by using in-situ magnetic resonance imaging. Three different MH decomposition modes were used, and water flow erosion was employed to eliminate the problem of incomplete MH decomposition in the later stages of depressurization, which is caused by insufficient driving forces and slower heat and mass transfer due to lower decomposition pressure and the protection effect of water films. The promotion of MH decomposition by water flow erosion was experimentally confirmed. Depressurization could decrease water-phase permeability in the sediment core and further optimize the water flow environment. Water flow erosion could greatly accelerate heat and mass transfer and provided extra driving force by increasing the chemical potential difference in the later stages of depressurization. In addition, the phenomenon of ice formation caused by sudden depressurization could be relieved by water flow erosion, which improved the ambient heat transfer, further changing the MH decomposition characteristics. The mutual promotion of MH decomposition by water flow erosion and depressurization was clearly demonstrated in this study.
Joo Yong Lee - One of the best experts on this subject based on the ideXlab platform.
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The Effects of Coupling Stiffness and Slippage of Interface Between the Wellbore and Unconsolidated Sediment on the Stability Analysis of the Wellbore Under Gas Hydrate Production
Energies, 2019Co-Authors: Jung-tae Kim, Ah-ram Kim, Gye-chun Cho, Chul-whan Kang, Joo Yong LeeAbstract:Gas Hydrates have great potential as future energy resources. Several productivity and stability analyses have been conducted for the Ulleung Basin, and the depressurization method is being considered for Production. Under depressurization, ground settlement occurs near the wellbore and axial stress develops. For a safe Production test, it is essential to perform a stability analysis for the wellbore and Hydrate-bearing sediments. In this study, the development of axial stress on the wellbore was investigated considering the coupling stiffness of the interface between the wellbore and sediment. A coupling stiffness model, which can consider both confining stress and slippage phenomena, was suggested and applied in a numerical simulation. Parametric analyses were conducted to investigate the effects of coupling stiffness and slippage on axial stress development. The results show that shear coupling stiffness has a significant effect on wellbore stability, while normal coupling stiffness has a minor effect. In addition, the maximum axial stress of the well bore has an upper limit depending on the magnitude of the confining stress, and the axial stress converges to this upper limit due to slipping at the interface. The results can be used as fundamental data for the design of wellbore under depressurization-based Gas Production.
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The Production-induced geomechanical property changes during Gas Production from Gas Hydrate deposits
Day 3 Wed May 08 2019, 2019Co-Authors: Joo Yong Lee, Gye-chun Cho, Jong-sub Lee, Tae-hyuk KwonAbstract:Abstract Gas Hydrates are widespread, occurring in both permafrost and deep sea sediments. The large estimated areas of Gas Hydrate reservoirs suggest that the high potential of Gas Hydrates as an energy resource if economically viable Production methods were developed. The Production of natural Gas from Gas Hydrate deposits poses challenges such as assessing Hydrate recovery rates from physical properties and geological structure of the Hydrate reservoir, securing the economic viability of produced Gas from a particular resource, and keeping process safe from geomechanical impacts from Hydrate dissociation. During the Hydrate dissociation and the subsequent Gas Production from dissociated Gas Hydrate, geomechanical property changes due to the sediment deformation, the changes in Hydrate saturations, and fine migrations. In this study, extensive laboratory studies have been conducted to quantify these issues and the implications of these changes to the Gas Production from Gas Hydrate deposits have been investigated. Strength, stiffness, permeability changes due to Gas Hydrate saturations were examined in high-pressure oedometric system and tri-axial system. Fine migrations characteristics and the subsequent property changes were examined with many different experimental systems. The experimental system includes core-flooding system with X-ray CT monitoring, oedometric system, triaxial system, and one-dimensional fine migration experiment system. The sediment used in this study is synthesized Gas Hydrate-bearing sediments and the mean grain size of the sediments lies in fine sands. Hydrate saturation ranges from 10 to 50%. Fine fraction ranges also from 10 to 50%. Sediment deformation from compressive stress concentration generally increases stiffness and decreases permeability. Hydrate saturation decrease induced from Gas Hydrate Production generally decrease strength and stiffness and increase permeability. The property changes are not linearly related to Gas Hydrate saturations and the relations differ depending on the character of deposits. Fine migrations induced by Gas Hydrate Production alter fine contents in producing intervals and also would change geomechanical properties. Moving particles generally concentrates near well-bore but the locus of concentration depends on the character of the producing interval, such as grain size distributions and flow rate. Even a small fraction of fine particles can induce significant changes in physical properties. In fine-concentrated zones, stiffness generally increases and permeability generally decreases. The quantifications of these phenomena based on the systematic and extensive experimental studies are the essential steps before the development of THM numerical simulation code for Gas Hydrate Production. For near future the quantitative relations in this study will be implemented to THM simulation code for Gas Hydrate Production.
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Estimation of model parameters and properties for numerical simulation on geomechanical stability of Gas Hydrate Production in the Ulleung Basin, East Sea, Korea
Quaternary International, 2017Co-Authors: Ah-ram Kim, Gye-chun Cho, Hak-sung Kim, Joo Yong LeeAbstract:Abstract The process of Hydrate dissociation and Production induced by depressurization incorporates intricate hydraulic, thermal, and mechanical phenomena. Thus, coupled thermal-hydraulic-mechanical (T-H-M) simulation is critically necessary to evaluate the geomechanical stability of Hydrate Production in Hydrate-bearing sediments (HBS). However, methods of estimating the input model parameters and properties of the target reservoir, in particular in unconsolidated marine sediments, have received limited attention compared to studies on Production simulators. The T-H-M properties of the marine sediments change considerably with depth, geological strata, and soil type of each layer. Therefore, it is important that representative layers and their corresponding T-H-M properties should be properly estimated to analyze the stability and productivity of methane Gas recovery in the field. This study provides a comprehensive estimation for the model parameters and properties of unconsolidated marine sediments, based on vast data from field seismic surveys and laboratory experimental results with core samples, investigates empirical correlations between model parameters and methane Hydrate saturation, and finally summarizes the estimated model parameters and properties, which can possibly be applied to on-going numerical research into stability assessment of the pilot Gas Hydrate (GH) Production test, which is soon to be performed in the Ulleung basin.
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Geomechanical Responses During Gas Hydrate Production Induced by Depressurization
Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology, 2016Co-Authors: Ah-ram Kim, Gye-chun Cho, Joo Yong Lee, Se-joon KimAbstract:Methane Hydrate has been received large attention as a new energy source instead of oil and fossil fuel. However, there is high potential for geomechanical stability problems such as marine landslides, seafloor subsidence, and large volume contraction in the Hydrate-bearing sediment during Gas Production induced by depressurization. In this study, a thermal-hydraulic-mechanical coupled numerical analysis is conducted to simulate methane Gas Production from the Hydrate deposits in the Ulleung basin, East Sea, Korea. The field-scale axisymmetric model incorporates the physical processes of Hydrate dissociation, pore fluid flow, thermal changes (i.e., latent heat, conduction and advection), and geomechanical behaviors of the Hydrate-bearing sediment. During depressurization, deformation of sediments around the Production well is generated by the effective stress transformed from the pore pressure difference in the depressurized region. This tendency becomes more pronounced due to the stiffness decrease of Hydrate-bearing sediments which is caused by Hydrate dissociation.
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Energy-efficient natural Gas Hydrate Production using Gas exchange
Applied Energy, 2016Co-Authors: Dong-yeun Koh, Hyery Kang, Jong-won Lee, Youngjune Park, Se-joon Kim, Jaehyoung Lee, Joo Yong Lee, Huen LeeAbstract:Abstract Breaking the bounds of classical natural Gas Hydrate (NGH) Production processes, a newborn concept based on the Gas exchange mechanism provides an opportunity to catch two birds with one stone: simultaneously achieving the sequestration of CO 2 for climate change mitigation and the enhanced recovery of CH 4 for energy Production. As a ‘new paradigm’ in NGH Production schemes, the non-destructive Gas exchange as one of the most stable and promising NGH recovery approaches has received much attention in the fields of physics, chemistry, chemical engineering, civil engineering, petroleum engineering and geology. In this review, we assess the state-of-the-art Gas exchange concept for NGH Production by understanding its principles and developments, with emphasis on another technical breakthrough using the CO 2 + N 2 Gas mixture injection. After establishing the fundamentals of the Gas exchange process, we make a general survey of the NGH field Production in the North Slope of Alaska in 2012, which practically adopted the Gas exchange as a key technology. Several recent international NGH field Production tests that basically use depressurization are also briefly analyzed for comparison. We suggest that the Gas exchange method is ready to be tested in the NGH deposits with the valuable lessons learned from past pioneering tests.
