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Yi Wang - One of the best experts on this subject based on the ideXlab platform.
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The determining factor of Hydrate Dissociation rate in the sediments with different water saturations
'Elsevier BV', 2020Co-Authors: Li Xiao-yan, Yi Wang, Li Xiao-sen, Liu Jian-wu, Hu Heng-qiAbstract:In nature, gas Hydrate is mainly distributed in permafrost region and deep ocean sediments. For these two types of Hydrate reservoirs, water contents in the sediments were different. The water content has a large influence on the characteristics of heat transfer and fluid flow in the sediments, thereby affecting the Hydrate Dissociation behavior. In this paper, the experiments of Hydrate Dissociation by depressurization in sediments with different water saturations were conducted. The influences of water saturation on the pressure, the temperature, the gas production, the water production, and the Hydrate Dissociation rate were analyzed. The experimental results showed that, in the depressurization stage (DS), the rate of pressure dropping and the amount of Hydrate reformation increased with the raise of the water saturation in the sediments. In the constant pressure stage (CPS), although the heat conduction rate of the sediments increased with the increase of the water saturation, the mass transport rate of the gas released from Hydrate Dissociation was limited due to the increase of water saturation. As a result, the Hydrate Dissociation rate decreased with the increase of the water saturation in the sediments. According to these experimental results, during the Hydrate Dissociation in the sediments with different water saturations, the Hydrate Dissociation rate is determined by the mass transport rate of the gas released from the Hydrate Dissociation. For the Hydrate reservoirs with the high-water saturation, the Hydrate Dissociation rate is largely limited by the diffusion rate of gas released from Hydrate Dissociation. Hence, the key factor to improve the Hydrate Dissociation rate in the sediments with high water saturation is to increase the diffusion rate of gas in the sediments. (C) 2020 Elsevier Ltd. All rights reserved
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Optimization of the Production Pressure for Hydrate Dissociation by Depressurization
'American Chemical Society (ACS)', 2020Co-Authors: Li Xiao-yan, Yi Wang, Li Xiao-sen, Yu ZhangAbstract:Natural gas Hydrate is considered as a promising energy resource in the future. How to choose a suitable production pressure is a key issue when depressurization is taken as the production way of gas Hydrate. In this study, we conducted the experiments of methane Hydrate Dissociation under different production pressures. The influences of production pressure on the Hydrate Dissociation rate and the method to optimize the production pressure were studied. The experimental results illustrated that two stages were contained in the Hydrate Dissociation by depressurization: the depressurization stage (DS) and the constant pressure stage (CPS). In the DS, the sensible heat of the sediments was used for Hydrate Dissociation, and the Hydrate Dissociation amount increased with the decrease of the production pressure. In the CPS, the required heat for Hydrate Dissociation was transferred from the surroundings. As the production pressure decreased, the Hydrate Dissociation rate increased. Although the lower production pressure can improve the Hydrate Dissociation rate, the energy input of Hydrate production in field for depressurization with the lower production pressure could be larger than that with the higher production pressure. In order to improve the production efficiency, an optimizing method of production pressure was first proposed. Based on the experimental data, the optimum production pressure was calculated with this method. The calculation result indicates that the production pressure should be as close to the pressure of Hydrate quadruple point (2.56 MPa) as possible. Moreover, it is worth noting that the optimum production pressure in field production could be different from that obtained by experiments because the optimum production pressure is determined by the actual function of the energy input in field. However, the evaluation method is universal
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The determining factor of Hydrate Dissociation rate in the sediments with different water saturations
Energy, 2020Co-Authors: Yi Wang, Jian-wu LiuAbstract:Abstract In nature, gas Hydrate is mainly distributed in permafrost region and deep ocean sediments. For these two types of Hydrate reservoirs, water contents in the sediments were different. The water content has a large influence on the characteristics of heat transfer and fluid flow in the sediments, thereby affecting the Hydrate Dissociation behavior. In this paper, the experiments of Hydrate Dissociation by depressurization in sediments with different water saturations were conducted. The influences of water saturation on the pressure, the temperature, the gas production, the water production, and the Hydrate Dissociation rate were analyzed. The experimental results showed that, in the depressurization stage (DS), the rate of pressure dropping and the amount of Hydrate reformation increased with the raise of the water saturation in the sediments. In the constant pressure stage (CPS), although the heat conduction rate of the sediments increased with the increase of the water saturation, the mass transport rate of the gas released from Hydrate Dissociation was limited due to the increase of water saturation. As a result, the Hydrate Dissociation rate decreased with the increase of the water saturation in the sediments. According to these experimental results, during the Hydrate Dissociation in the sediments with different water saturations, the Hydrate Dissociation rate is determined by the mass transport rate of the gas released from the Hydrate Dissociation. For the Hydrate reservoirs with the high-water saturation, the Hydrate Dissociation rate is largely limited by the diffusion rate of gas released from Hydrate Dissociation. Hence, the key factor to improve the Hydrate Dissociation rate in the sediments with high water saturation is to increase the diffusion rate of gas in the sediments.
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Sediment deformation and strain evaluation during methane Hydrate Dissociation in a novel experimental apparatus
Applied Energy, 2020Co-Authors: Yi Wang, Jingchun Feng, Xuan Kou, Yu ZhangAbstract:Abstract Natural gas Hydrate is an efficient alternative future energy source because huge reserves of methane gas are caged in Hydrate-bearing sediments. The research on the deformation of sediments during Hydrate Dissociation is important for safe Hydrate production. In this work, a novel experimental apparatus was designed and built to investigate sediment deformation and strain evaluation during methane Hydrate Dissociation by depressurization. Experimental results are compared for methane Hydrate Dissociation for various Hydrate saturations, porosities, and particle sizes of sediments. Experimental results illustrate that gas Hydrate Dissociation by depressurization experienced three main stages. The phenomenon secondary Hydrate formation was found during Hydrate Dissociation by depressurization, which leads to the decrease of sediment permeability. The strain of the sediment is proportional to the volume of methane gas production. Higher Hydrate saturation leads to larger sediment deformation by Hydrate decomposition. Higher sediment porosity leads to looser sediment particles and larger sediment deformation during Hydrate Dissociation by depressurization. Larger sediment particle sizes lead to smaller interface areas between Hydrate and sediment particles, and larger sediment deformation during Hydrate Dissociation by depressurization.
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The consistency of the normalized Hydrate Dissociation rate in the Hydrate simulator with different scales
Fuel, 2020Co-Authors: Yi Wang, Yu Zhang, Kun Wan, Hao-peng ZengAbstract:Abstract Recently, in order to perform the gas production test from methane Hydrate reservoir in laboratory, the size of the experimental simulator is developing towards a larger scale. The characteristics of the heat transfer and the mass transport in the Hydrate-bearing sediments with different scales are varied, thereby resulting in the different Hydrate Dissociation behaviors. In this study, the SCHS (Small Cubic Hydrate Simulator, 0.729 L), the CHS (Cubic Hydrate Simulator, 5.832 L), and the PHS (Pilot-scale Hydrate Simulator, 117.8 L) in our laboratory were applied to study the Hydrate Dissociation by depressurization. The experimental results showed that, in the depressurization stage, the volume of the Hydrate Dissociation was determined by the sensible heat of the sediments and the heat transferred from the surroundings. During the constant pressure stage, the normalized Hydrate Dissociation rates (vnorm) was first proposed to define the average rate of the Hydrate Dissociation per temperature and per shape factor. The vnorm excluded the influence of the driving force of the heat transfer and the scale of the Hydrate simulator on the Hydrate Dissociation. Therefore, for the Hydrate simulator with different scales, the value of the vnorm for different production pressures were similar. The calculated value of the vnorm for different runs were not completely be same due to the experimental error. However, the average value of the vnorm for different runs could be used to predicate the average Hydrate Dissociation rate in the Hydrate simulator with other scales. For example, during the gas production from a Hydrate reservoir with the same shape and double length/radius of the PHS, the average Hydrate Dissociation rate can be calculated as 12.44 ml/min, and the total duration time of the Hydrate Dissociation can be calculated as 8.58 days.
Jingchun Feng - One of the best experts on this subject based on the ideXlab platform.
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Sediment deformation and strain evaluation during methane Hydrate Dissociation in a novel experimental apparatus
Applied Energy, 2020Co-Authors: Yi Wang, Jingchun Feng, Xuan Kou, Yu ZhangAbstract:Abstract Natural gas Hydrate is an efficient alternative future energy source because huge reserves of methane gas are caged in Hydrate-bearing sediments. The research on the deformation of sediments during Hydrate Dissociation is important for safe Hydrate production. In this work, a novel experimental apparatus was designed and built to investigate sediment deformation and strain evaluation during methane Hydrate Dissociation by depressurization. Experimental results are compared for methane Hydrate Dissociation for various Hydrate saturations, porosities, and particle sizes of sediments. Experimental results illustrate that gas Hydrate Dissociation by depressurization experienced three main stages. The phenomenon secondary Hydrate formation was found during Hydrate Dissociation by depressurization, which leads to the decrease of sediment permeability. The strain of the sediment is proportional to the volume of methane gas production. Higher Hydrate saturation leads to larger sediment deformation by Hydrate decomposition. Higher sediment porosity leads to looser sediment particles and larger sediment deformation during Hydrate Dissociation by depressurization. Larger sediment particle sizes lead to smaller interface areas between Hydrate and sediment particles, and larger sediment deformation during Hydrate Dissociation by depressurization.
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Influence of the Particle Size of Sandy Sediments on Heat and Mass Transfer Characteristics during Methane Hydrate Dissociation by Thermal Stimulation
Energies, 2019Co-Authors: Yi Wang, Lei Zhan, Jingchun FengAbstract:Natural gas Hydrate could be regarded as an alternative energy source in the future. Therefore, the investigation of the gas production from Hydrate reservoirs is attracting extensive attention. In this work, a novel set-up was built to investigate sand production and sediment deformation during Hydrate Dissociation by heat stimulation. The influence of the particle sizes on the Hydrate Dissociation and sediment deformation was first investigated experimentally. The experimental results indicated that the rate of Hydrate decomposition by heat stimulation was in proportion to the particle size of the sediment. The heat transfer rate and the energy efficiency decreased with the decrease of the particle size of the sediment. This was because higher permeability might lead to a larger sweep area of the fluid flow, which was beneficial for the supply of heat for Hydrate Dissociation. The sand production was found during Hydrate Dissociation by heat stimulation. The particle migration was due to the hydrodynamics of the water injection. The sand sediment expanded under the drive force from water injection and Hydrate Dissociation. Additionally, the smaller permeability led to the larger pressure difference leading to the larger sediment deformation. Because the sediment became loose after Hydrate Dissociation, small particle migration due to the hydrodynamics of the water injection could happen during the experiments. However, the sand production in the sediment with the larger particle size was more difficult, because the larger particles were harder to move due to the hydrodynamics, and the larger particles were harder to move across the holes on the production well with a diameter of 1 mm. Therefore, the sediment deformation during Hydrate Dissociation by heat stimulation should not be ignored.
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Large Scale Experimental Evaluation to Methane Hydrate Dissociation below Quadruple Point by Depressurization Assisted with Heat Stimulation
Energy Procedia, 2017Co-Authors: Jingchun Feng, Yi WangAbstract:Abstract The Pilot-Scale Hydrate Simulator (PHS), a three-dimensional 117.8 L pressure vessel, is applied to study the methane Hydrate Dissociation below the quadruple point in the sandy sediment in this work. The Hydrate Dissociation behaviors below and above the quadruple point by depressurization method and depressurization assisted with heat stimulation method are compared. The results indicate that methane Hydrate Dissociation below the quadruple point causes ice formation, which can strongly enhance the Dissociation rate of the Hydrate. The water generated from Hydrate Dissociation below the quadruple point may immediately form ice. Meanwhile, the Hydrate Dissociation below the quadruple point consumes the latent heat released by ice formation. In addition, it is found by depressurization assisted with heat stimulation that the heat injection has little influence on Hydrate Dissociation, because the injected heat is used for ice melting rather than Hydrate Dissociation.
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Entropy generation analysis of Hydrate Dissociation by depressurization with horizontal well in different scales of Hydrate reservoirs
Energy, 2017Co-Authors: Jingchun Feng, Yi WangAbstract:Based on the Hydrate conditions of the South China Sea, Hydrate samples were synthesized in the Cubic Hydrate Simulator (CHS) and the Pilot-Scale Hydrate Simulator (PHS), and Hydrate Dissociation experiments by depressurization with single horizontal well were carried out. In order to illuminate the characteristic of the irreversible energy loss during the gas production process in a large-scale Hydrate simulator and a smaller Hydrate simulator, the entropy generation model was established. Results show that the evolutions of the pressure, temperature, gas production, and water production during Hydrate Dissociation process with different scales of Hydrate reservoir are similar. Moreover, entropy generation in the mixed gas release stage is the largest. In addition, in the dissociated gas release stage, the ratio of entropy generation decreases remarkably with the increase of the Hydrate reservoir scale, and constant-pressure depressurization method is favorable for Hydrate Dissociation in a larger scale Hydrate reservoir.
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experimental and modeling analyses of scaling criteria for methane Hydrate Dissociation in sediment by depressurization
Applied Energy, 2016Co-Authors: Yi Wang, Jingchun Feng, Xiaosen Li, Yu ZhangAbstract:Three high pressure reactors with different inner volumes, which are named as the Pilot-scale Hydrate Simulator (PHS), the Cubic Hydrate Simulator (CHS), and the Small Cubic Hydrate Simulator (SCHS), are applied for investigating Hydrate Dissociation by depressurization method. The volume of the PHS, the CHS, and the SCHS are 117.80L, 5.80L, and 0.73L, respectively. Meanwhile, the model of scaling criterion for Hydrate Dissociation by the depressurization method is developed as well. The scaling criteria are verified and modified by the Hydrate Dissociation experiments with different scales. Finally, the gas production from a field scale Hydrate reservoir (FSHR) is predicted by scaling the experimental results using the modified scaling criteria. The results indicate that the ratios of gas production in the depressurizing (DP) stage are similar to the ratios of inner volume, which verify the scaling criteria in the DP stage. However, the scaling criteria for the experiments in the constant-pressure (CP) stages need to be modified by the experimental results. The correction factor is 0.89. By using the modified scaling criteria, the gas production behavior, the Hydrate Dissociation process, and the heat transfer process in a larger scale Hydrate reservoir can be predicted. The maximum deviations between the calculated value and experimental result are less than 16%, which can be accepted. In the FSHR with the diameter of 50m and the length of 60m, the predicted results indicate that 3.74×106m3 of gas are produced in 120h (5days) during the DP stage, and 1.94×106m3 of gas are produced in 1.86×105h (7750days) during the CP stage.
Yu Zhang - One of the best experts on this subject based on the ideXlab platform.
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Optimization of the Production Pressure for Hydrate Dissociation by Depressurization
'American Chemical Society (ACS)', 2020Co-Authors: Li Xiao-yan, Yi Wang, Li Xiao-sen, Yu ZhangAbstract:Natural gas Hydrate is considered as a promising energy resource in the future. How to choose a suitable production pressure is a key issue when depressurization is taken as the production way of gas Hydrate. In this study, we conducted the experiments of methane Hydrate Dissociation under different production pressures. The influences of production pressure on the Hydrate Dissociation rate and the method to optimize the production pressure were studied. The experimental results illustrated that two stages were contained in the Hydrate Dissociation by depressurization: the depressurization stage (DS) and the constant pressure stage (CPS). In the DS, the sensible heat of the sediments was used for Hydrate Dissociation, and the Hydrate Dissociation amount increased with the decrease of the production pressure. In the CPS, the required heat for Hydrate Dissociation was transferred from the surroundings. As the production pressure decreased, the Hydrate Dissociation rate increased. Although the lower production pressure can improve the Hydrate Dissociation rate, the energy input of Hydrate production in field for depressurization with the lower production pressure could be larger than that with the higher production pressure. In order to improve the production efficiency, an optimizing method of production pressure was first proposed. Based on the experimental data, the optimum production pressure was calculated with this method. The calculation result indicates that the production pressure should be as close to the pressure of Hydrate quadruple point (2.56 MPa) as possible. Moreover, it is worth noting that the optimum production pressure in field production could be different from that obtained by experiments because the optimum production pressure is determined by the actual function of the energy input in field. However, the evaluation method is universal
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Sediment deformation and strain evaluation during methane Hydrate Dissociation in a novel experimental apparatus
Applied Energy, 2020Co-Authors: Yi Wang, Jingchun Feng, Xuan Kou, Yu ZhangAbstract:Abstract Natural gas Hydrate is an efficient alternative future energy source because huge reserves of methane gas are caged in Hydrate-bearing sediments. The research on the deformation of sediments during Hydrate Dissociation is important for safe Hydrate production. In this work, a novel experimental apparatus was designed and built to investigate sediment deformation and strain evaluation during methane Hydrate Dissociation by depressurization. Experimental results are compared for methane Hydrate Dissociation for various Hydrate saturations, porosities, and particle sizes of sediments. Experimental results illustrate that gas Hydrate Dissociation by depressurization experienced three main stages. The phenomenon secondary Hydrate formation was found during Hydrate Dissociation by depressurization, which leads to the decrease of sediment permeability. The strain of the sediment is proportional to the volume of methane gas production. Higher Hydrate saturation leads to larger sediment deformation by Hydrate decomposition. Higher sediment porosity leads to looser sediment particles and larger sediment deformation during Hydrate Dissociation by depressurization. Larger sediment particle sizes lead to smaller interface areas between Hydrate and sediment particles, and larger sediment deformation during Hydrate Dissociation by depressurization.
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The consistency of the normalized Hydrate Dissociation rate in the Hydrate simulator with different scales
Fuel, 2020Co-Authors: Yi Wang, Yu Zhang, Kun Wan, Hao-peng ZengAbstract:Abstract Recently, in order to perform the gas production test from methane Hydrate reservoir in laboratory, the size of the experimental simulator is developing towards a larger scale. The characteristics of the heat transfer and the mass transport in the Hydrate-bearing sediments with different scales are varied, thereby resulting in the different Hydrate Dissociation behaviors. In this study, the SCHS (Small Cubic Hydrate Simulator, 0.729 L), the CHS (Cubic Hydrate Simulator, 5.832 L), and the PHS (Pilot-scale Hydrate Simulator, 117.8 L) in our laboratory were applied to study the Hydrate Dissociation by depressurization. The experimental results showed that, in the depressurization stage, the volume of the Hydrate Dissociation was determined by the sensible heat of the sediments and the heat transferred from the surroundings. During the constant pressure stage, the normalized Hydrate Dissociation rates (vnorm) was first proposed to define the average rate of the Hydrate Dissociation per temperature and per shape factor. The vnorm excluded the influence of the driving force of the heat transfer and the scale of the Hydrate simulator on the Hydrate Dissociation. Therefore, for the Hydrate simulator with different scales, the value of the vnorm for different production pressures were similar. The calculated value of the vnorm for different runs were not completely be same due to the experimental error. However, the average value of the vnorm for different runs could be used to predicate the average Hydrate Dissociation rate in the Hydrate simulator with other scales. For example, during the gas production from a Hydrate reservoir with the same shape and double length/radius of the PHS, the average Hydrate Dissociation rate can be calculated as 12.44 ml/min, and the total duration time of the Hydrate Dissociation can be calculated as 8.58 days.
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Experimental study of methane Hydrate Dissociation in porous media with different thermal conductivities
International Journal of Heat and Mass Transfer, 2019Co-Authors: Yi Wang, Yu Zhang, Zhaoyang ChenAbstract:Abstract Methane Hydrate Dissociation is an endothermic reaction. Therefore, one of important factors for methane Hydrate Dissociation is the heat transfer rate. In order to study the heat transfer characteristics of porous media on methane Hydrate Dissociation, experiments of methane Hydrate Dissociation using depressurization are conducted in porous media with different thermal conductivities, including quartz sand (0.926 W/(m·K)), white corundum (28.82 W/(m·K)) and silicon carbide (41.9 W/(m·K)). Experimental results show that, during the depressurization stage (DS), the temperature difference among different positions in quartz sand is larger than that in white corundum and silicon carbide. Since the heat transfer rate of quartz sand is smallest among three kinds of sand. A low temperature zone at the center of the reactor is observed in quartz sand compared to white corundum and silicon carbide. During the constant pressure stage (CPS), as the thermal conductivity of porous media increases, the temperature rising rate increases, and the duration of the CPS decreases. The Dissociation rate of methane Hydrate is controlled by the heat transfer rate of sediments during the CPS. The minimum gas production rate is obtained from the experimental in quartz sand, and the maximum gas production rate is obtained from the experiment in silicon carbide. This result indicates that the Dissociation rate of Hydrate increased with the increase of the thermal conductivity of porous media. Meanwhile, the overall rate constants (koverall) for different runs are calculated to quantify the dissociate rate of methane Hydrate during the CPS. As the thermal conductivities of porous media increase, the overall rate constant of methane Hydrate Dissociation increases. The results of this study are important for understanding the effects of thermal conductivity of porous media on Hydrate Dissociation in actual field. Furthermore, it can also be used for the validation of numerical simulation in future.
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Influence of heat conduction and heat convection on Hydrate Dissociation by depressurization in a pilot-scale Hydrate simulator
Applied Energy, 2019Co-Authors: Xuan Kou, Yi Wang, Yu Zhang, Zhaoyang ChenAbstract:Abstract Natural gas Hydrate, as an unconventional energy resource, has generated considerable research interest. It is generally accepted that depressurization method is the most practical and economically promising way to produce gas from gas Hydrate sediments. Rates of Hydrate Dissociation by depressurization depend on heat transfer rate, and the heat transfer during Hydrate Dissociation mainly includes heat conduction and heat convection. In this paper the Pilot-Scale Hydrate Simulator (PHS), with an inner volume of 117.8 L, was applied to investigate the influence of heat conduction and heat convection on Hydrate Dissociation. Different thermal boundary conditions and different flow directions during gas recovery from Hydrate reservoir by depressurization were performed in the PHS. In addition, the method of studying the effect of different directions of heat convection by changing well locations was firstly proposed in this paper. It was obtained from experimental results that the Hydrate Dissociation rate with an isothermal boundary is faster than that with a semi-adiabatic boundary, and heat conduction is the dominant factor in Hydrate Dissociation by depressurization in the constant pressure stage. The influence of heat convection on Hydrate Dissociation in the constant pressure stage may not be obvious, but during the depressurizing stage, the opposite direction of fluid flow and heat transfer can promote Hydrate reformation, and has effect on fluid flow characteristics inside the reservoir. These findings can provide theoretical references for field tests of exploiting natural gas Hydrate.
Xiaosen Li - One of the best experts on this subject based on the ideXlab platform.
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experimental and modeling analyses of scaling criteria for methane Hydrate Dissociation in sediment by depressurization
Applied Energy, 2016Co-Authors: Yi Wang, Jingchun Feng, Xiaosen Li, Yu ZhangAbstract:Three high pressure reactors with different inner volumes, which are named as the Pilot-scale Hydrate Simulator (PHS), the Cubic Hydrate Simulator (CHS), and the Small Cubic Hydrate Simulator (SCHS), are applied for investigating Hydrate Dissociation by depressurization method. The volume of the PHS, the CHS, and the SCHS are 117.80L, 5.80L, and 0.73L, respectively. Meanwhile, the model of scaling criterion for Hydrate Dissociation by the depressurization method is developed as well. The scaling criteria are verified and modified by the Hydrate Dissociation experiments with different scales. Finally, the gas production from a field scale Hydrate reservoir (FSHR) is predicted by scaling the experimental results using the modified scaling criteria. The results indicate that the ratios of gas production in the depressurizing (DP) stage are similar to the ratios of inner volume, which verify the scaling criteria in the DP stage. However, the scaling criteria for the experiments in the constant-pressure (CP) stages need to be modified by the experimental results. The correction factor is 0.89. By using the modified scaling criteria, the gas production behavior, the Hydrate Dissociation process, and the heat transfer process in a larger scale Hydrate reservoir can be predicted. The maximum deviations between the calculated value and experimental result are less than 16%, which can be accepted. In the FSHR with the diameter of 50m and the length of 60m, the predicted results indicate that 3.74×106m3 of gas are produced in 120h (5days) during the DP stage, and 1.94×106m3 of gas are produced in 1.86×105h (7750days) during the CP stage.
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Hydrate Dissociation induced by depressurization in conjunction with warm brine stimulation in cubic Hydrate simulator with silica sand
Applied Energy, 2016Co-Authors: Jingchun Feng, Yi Wang, Xiaosen LiAbstract:To study the effect of salt concentration of brine injection on Hydrate Dissociation, Hydrate Dissociation experiments induced by depressurization in conjunction with warm brine stimulation have been carried out in a Cubic Hydrate Simulator (CHS). The dual horizontal wells were set as the well configuration. The results indicate that the salinity in the reservoir decreases continuously during the depressurizing stage under the mixture of fresh water from Hydrate Dissociation. However, the salinity increases overtime during the constant-pressure stage (the injection stage) by the mass transfer with the injected brine. The gas production rate and heat-transfer rate for pure water injection are lower than those for brine injection. In addition, raising the injected salinity can enhance the rates of heat transfer and gas production when the salinity is lower than 10.0%. However, the promotion effect of brine injection on Hydrate Dissociation is limited when the injected salinity is beyond 10.0%. This is because the specific heat of the brine declines with the increase of the salinity, which causes the decrease of heat injection rate. The water production rate equals to the water injection rate in the process of brine injection. The energy analysis and the evaluation of energy ratio indicate that the optimal injected salinity in this work is 10.0%.
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large scale experimental evaluation to methane Hydrate Dissociation below quadruple point in sandy sediment
Applied Energy, 2016Co-Authors: Yi Wang, Yu Zhang, Jingchun Feng, Xiaosen Li, Gang LiAbstract:The Pilot-Scale Hydrate Simulator (PHS), a three-dimensional 117.8L pressure vessel, is applied to study the methane Hydrate Dissociation below the quadruple point in the sandy sediment in this work. The Hydrate Dissociation behaviors below and above the quadruple point are compared. The influences of the production pressure, the initial reservoir temperature, and the water saturation on the Hydrate Dissociation below the quadruple point by depressurization are investigated. The results indicate that methane Hydrate Dissociation below the quadruple point causes ice formation, which can strongly enhance the Dissociation rate of the Hydrate. The water generated from Hydrate Dissociation below the quadruple point may immediately form ice and the pore water in the reservoir turns into ice at the same time. Meanwhile, the Hydrate Dissociation below the quadruple point consumes the latent heat released by ice formation. The lower production pressure causes the higher driving force for Hydrate Dissociation and ice formation, which results in the higher Dissociation rate of the Hydrate. In addition, when the production pressure is lower than the quadruple point, a lower initial reservoir temperature is favorable for ice formation, which leads to the higher Hydrate Dissociation rate. The experimental results from Hydrate Dissociation in the ‘water-saturated’ reservoir and ‘gas-saturated’ reservoir indicate that the rate of ice formation is slower in the ‘water-saturated’ reservoir.
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investigation into optimization condition of thermal stimulation for Hydrate Dissociation in the sandy reservoir
Applied Energy, 2015Co-Authors: Jingchun Feng, Yi Wang, Xiaosen Li, Gang Li, Zhaoyang Chen, Yu ZhangAbstract:Investigation of the optimal injection temperature for the Hydrate Dissociation plays a significant role in the gas Hydrate exploitation in the practical field. In this work, the experiments of Hydrate Dissociation by depressurization in conjunction with thermal stimulation (DT) with the different injection temperatures are carried out in a Cubic Hydrate Simulator (CHS). Evaluation of the entropy production minimization (EPM), the energy ratio and the thermal efficiency are employed to investigate into the optimized injection temperature for Hydrate Dissociation. The thermal efficiency decreases with the increase of the injection temperature. The optimal injection temperatures for the Hydrate Dissociation from the points of the maximization of the energy ratio and the minimization of the entropy production, which are equivalent to maximizing the energy production and minimizing the energy consumption, respectively, are 38.8°C and 37.9°C. The results of evaluations from the two aspects are in a quite good agreement. Thus, the warm water injection of approximately 38–39°C is suitable for Hydrate Dissociation with the DT method, and the hot water injection beyond 39°C is uneconomical for Hydrate Dissociation.
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production behaviors and heat transfer characteristics of methane Hydrate Dissociation by depressurization in conjunction with warm water stimulation with dual horizontal wells
Energy, 2015Co-Authors: Jingchun Feng, Yi Wang, Xiaosen Li, Gang Li, Zhaoyang ChenAbstract:To investigate into the synergistic effect of depressurization and heat stimulation on Hydrate Dissociation and the three-dimensional heat transfer characteristics during Hydrate Dissociation in the porous media, a series of the Hydrate Dissociation experimental runs by the depressurization in conjunction with warm water injection with DWDH (dual horizontal wells) and single depressurization have been carried out in a three-dimensional CHS (cubic Hydrate simulator). The results indicate that the gas production process can be divided into the free gas release stage, the mixed gas release stage, and the dissociated gas release stage. In the first two stages, the gas production is mainly controlled by the depressurizing rate. In the third stage, the duration of the Hydrate Dissociation with the DWDH method (water injection temperature equals to environmental temperature) is much shorter than that by the single depressurization. It is due to the fact that water injection enhances the heat convection and further increases the rate of the Hydrate Dissociation. The analysis of three-dimensional heat transfer shows that the heat transfer rate along the injection well is the fastest. Energy analysis indicates that the sensible heat of the Hydrate reservoir is insufficient for the Hydrate Dissociation, and the heat for the Hydrate Dissociation mainly originates from the boundaries.
Gang Li - One of the best experts on this subject based on the ideXlab platform.
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heat transfer analysis of methane Hydrate Dissociation by depressurization and thermal stimulation
International Journal of Heat and Mass Transfer, 2018Co-Authors: Hu Si, Bo Li, Gang LiAbstract:Abstract The Dissociation of natural gas Hydrate is an endothermic reaction closely related with the heat transfer characteristics in porous media. This study mainly focuses on the three-dimensional heat transfer behaviors during Hydrate Dissociation by depressurization and thermal stimulation based on the experiments in a Cuboid Pressure Vessel (CPV). The evolution of various heat flows (including the heat transferred from the boundaries QB, the injected heat from the well Qinj, the heat consumed by the Hydrate Dissociation QH, and the sensible heat change of the deposit QS) and their relationships during Hydrate Dissociation are obtained through numerical simulation. The heat loss QL during gas production is calculated and analyzed for the first time. It is found that the Hydrate Dissociation is mainly promoted by the driving forces of depressurization (Fdep) and thermal stimulation (Fths), which are dependent on the heat flows of QB and Qinj, respectively. The effect of Fdep will be weakened under higher Fths. Part of Qinj and QB are absorbed and stored as QS by the porous media and the fluids of the deposit. Once QB becomes negative, it starts to make contribution to the heat loss instead of the Hydrate Dissociation, resulting in a sharp increase of QL. In addition, a proper thermal stimulation rate q and production pressure PW should be selected so that the Hydrate Dissociation rate could be significantly enhanced while the thermal efficiency and energy efficiency are still favorable when compared with using single depressurization.
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large scale experimental evaluation to methane Hydrate Dissociation below quadruple point in sandy sediment
Applied Energy, 2016Co-Authors: Yi Wang, Yu Zhang, Jingchun Feng, Xiaosen Li, Gang LiAbstract:The Pilot-Scale Hydrate Simulator (PHS), a three-dimensional 117.8L pressure vessel, is applied to study the methane Hydrate Dissociation below the quadruple point in the sandy sediment in this work. The Hydrate Dissociation behaviors below and above the quadruple point are compared. The influences of the production pressure, the initial reservoir temperature, and the water saturation on the Hydrate Dissociation below the quadruple point by depressurization are investigated. The results indicate that methane Hydrate Dissociation below the quadruple point causes ice formation, which can strongly enhance the Dissociation rate of the Hydrate. The water generated from Hydrate Dissociation below the quadruple point may immediately form ice and the pore water in the reservoir turns into ice at the same time. Meanwhile, the Hydrate Dissociation below the quadruple point consumes the latent heat released by ice formation. The lower production pressure causes the higher driving force for Hydrate Dissociation and ice formation, which results in the higher Dissociation rate of the Hydrate. In addition, when the production pressure is lower than the quadruple point, a lower initial reservoir temperature is favorable for ice formation, which leads to the higher Hydrate Dissociation rate. The experimental results from Hydrate Dissociation in the ‘water-saturated’ reservoir and ‘gas-saturated’ reservoir indicate that the rate of ice formation is slower in the ‘water-saturated’ reservoir.
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investigation into optimization condition of thermal stimulation for Hydrate Dissociation in the sandy reservoir
Applied Energy, 2015Co-Authors: Jingchun Feng, Yi Wang, Xiaosen Li, Gang Li, Zhaoyang Chen, Yu ZhangAbstract:Investigation of the optimal injection temperature for the Hydrate Dissociation plays a significant role in the gas Hydrate exploitation in the practical field. In this work, the experiments of Hydrate Dissociation by depressurization in conjunction with thermal stimulation (DT) with the different injection temperatures are carried out in a Cubic Hydrate Simulator (CHS). Evaluation of the entropy production minimization (EPM), the energy ratio and the thermal efficiency are employed to investigate into the optimized injection temperature for Hydrate Dissociation. The thermal efficiency decreases with the increase of the injection temperature. The optimal injection temperatures for the Hydrate Dissociation from the points of the maximization of the energy ratio and the minimization of the entropy production, which are equivalent to maximizing the energy production and minimizing the energy consumption, respectively, are 38.8°C and 37.9°C. The results of evaluations from the two aspects are in a quite good agreement. Thus, the warm water injection of approximately 38–39°C is suitable for Hydrate Dissociation with the DT method, and the hot water injection beyond 39°C is uneconomical for Hydrate Dissociation.
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production behaviors and heat transfer characteristics of methane Hydrate Dissociation by depressurization in conjunction with warm water stimulation with dual horizontal wells
Energy, 2015Co-Authors: Jingchun Feng, Yi Wang, Xiaosen Li, Gang Li, Zhaoyang ChenAbstract:To investigate into the synergistic effect of depressurization and heat stimulation on Hydrate Dissociation and the three-dimensional heat transfer characteristics during Hydrate Dissociation in the porous media, a series of the Hydrate Dissociation experimental runs by the depressurization in conjunction with warm water injection with DWDH (dual horizontal wells) and single depressurization have been carried out in a three-dimensional CHS (cubic Hydrate simulator). The results indicate that the gas production process can be divided into the free gas release stage, the mixed gas release stage, and the dissociated gas release stage. In the first two stages, the gas production is mainly controlled by the depressurizing rate. In the third stage, the duration of the Hydrate Dissociation with the DWDH method (water injection temperature equals to environmental temperature) is much shorter than that by the single depressurization. It is due to the fact that water injection enhances the heat convection and further increases the rate of the Hydrate Dissociation. The analysis of three-dimensional heat transfer shows that the heat transfer rate along the injection well is the fastest. Energy analysis indicates that the sensible heat of the Hydrate reservoir is insufficient for the Hydrate Dissociation, and the heat for the Hydrate Dissociation mainly originates from the boundaries.
