Experimental and Modeling Study of Kinetics for Hydrate Decomposition Induced by Depressurization in a Porous Medium

The hydrate decomposition kinetics is a key factor for the gas production from hydrate-saturated porous media. Meanwhile, it is also related to other factors. Among them, the permeability and hydrate dissociation surface area on hydrate dissociation kinetics have been studied experimentally and numerically in this work. First, the permeability to water was experimentally determined at different hydrate saturations (0%, 10%, 17%, 21%, 34%, 40.5%, and 48.75%) in hydrate-bearing porous media. By the comparison of permeability results from the experimental measurements and theoretical calculations with the empirical permeability models, it was found that, for the lower hydrate saturations (less than 40%), the experimental results of water permeability are closer to the predicted values of the grain-coating permeability model, whereas, for the hydrate saturation above 40%, the tendencies of hydrate accumulation in porous media are quite consistent with the pore-filling hydrate habits. A developed two-dimensional core-scale numerical code, which incorporates the models for permeability and hydrate dissociation surface area along with the hydrate accumulation habits in porous media, was used to investigate the kinetics of hydrate dissociation by depressurization, and a “shrinking-core” hydrate dissociation driven by the radial heat transfer was found in the numerical simulations of hydrate dissociation induced by depressurization in core-scale porous media. The numerical results indicate that the gas production from hydrates in porous media has a strong dependence on the permeability and hydrate dissociation surface area. Meanwhile, the simulation shows that the controlling factor for the dissociation kinetics of hydrate switches from permeability to hydrate dissociation surface area depending on the hydrate saturation and hydrate accumulation habits in porous media.

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Dynamic 3D imaging of gas hydrate kinetics using synchrotron computed tomography

E3S Web of Conferences ◽

10.1051/e3sconf/202020511004 ◽

2020 ◽

Vol 205 ◽

pp. 11004

Author(s):

Zaher Jarrar ◽

Riyadh Al-Raoush ◽

Khalid Alshibli ◽

Jongwon Jung

Keyword(s):

Surface Area ◽

Gas Hydrates ◽

Energy Demand ◽

Three Dimensional ◽

Hydrate Formation ◽

Gas Production ◽

Dissociation Kinetics ◽

Hydrate Dissociation ◽

Hydrate Saturation ◽

3D Volume

The availability of natural gas hydrates and the continuing increase in energy demand, motivated researchers to consider gas hydrates as a future source of energy. Fundamental understanding of hydrate dissociation kinetics is essential to improve techniques of gas production from natural hydrates reservoirs. During hydrate dissociation, bonds between water (host molecules) and gas (guest molecules) break and free gas is released. This paper investigates the evolution of hydrate surface area, pore habit, and tortuosity using in-situ imaging of Xenon (Xe) hydrate formation and dissociation in porous media with dynamic three-dimensional synchrotron microcomputed tomography (SMT). Xe hydrate was formed inside a high- pressure, low-temperature cell and then dissociated by thermal stimulation. During formation and dissociation, full 3D SMT scans were acquired continuously and reconstructed into 3D volume images. Each scan took only 45 seconds to complete, and a total of 60 scans were acquired. Hydrate volume and surface area evolution were directly measured from the SMT scans. At low hydrate saturation, the predominant pore habit was surface coating, while the predominant pore habit at high hydrate saturation was pore filling. A second-degree polynomial can be used to predict variation of tortuosity with hydrate saturation with an R2 value of 0.997.

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Surface area controls gas hydrate dissociation kinetics in porous media

Fuel ◽

10.1016/j.fuel.2018.07.030 ◽

2018 ◽

Vol 234 ◽

pp. 358-363 ◽

Cited By ~ 16

Author(s):

Xiongyu Chen ◽

D. Nicolas Espinoza

Keyword(s):

Porous Media ◽

Surface Area ◽

Gas Hydrate ◽

Dissociation Kinetics ◽

Hydrate Dissociation

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The Key Factors of Low-Frequency Electric Heating Assisted Depressurization Method in the Exploiting of Methane Hydrate Sediments

10.2118/205119-ms ◽

2021 ◽

Author(s):

Ermeng Zhao ◽

Jian Hou ◽

Yunkai Ji ◽

Lu Liu ◽

Yongge Liu ◽

...

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Specific Heat ◽

Specific Heat Capacity ◽

Low Frequency ◽

Electric Heating ◽

Gas Production ◽

Hydrate Decomposition ◽

Hydrate Saturation ◽

Production Behavior

Abstract Natural gas hydrate is widely distributed in the permafrost and marine deposits, and is regarded as an energy resource with great potential. The low-frequency electric heating assisted depressurization (LF-EHAD) has been proven to be an efficient method for exploiting hydrate sediments, which involves complex multi-physics processes, i.e. current conduction, multiphase flow, chemical reaction and heat transfer. The physical properties vary greatly in different hydrate sediments, which may profoundly affect the hydrate decomposition in the LF-EHAD process. In order to evaluate the influence of hydrate-bearing sediment properties on the gas production behavior and energy utilization efficiency of the LF-EHAD method, a geological model was first established based on the data of hydrate sediments in the Shenhu Area. Then, the influence of permeability, porosity, thermal conductivity, specific heat capacity, hydrate saturation and hydrate-bearing layer (HBL) thickness on gas production behavior is comprehensively analyzed by numerical simulation method. Finally, the energy efficiency ratio under different sediment properties is compared. Results indicate that higher gas production is obtained in the high-permeability hydrate sediments during depressurization. However, after the electric heating is implemented, the gas production first increases and then tends to be insensitive as the permeability decreases. With the increasing of porosity, the gas production during depressurization decreases due to the low effective permeability; while in the electric heating stage, this effect is reversed. High thermal conductivity is beneficial to enhance the heat conduction, thus promoting the hydrate decomposition. During depressurization, the gas production is enhanced with the increase of specific heat capacity. However, more heat is consumed to increase the reservoir temperature during electric heating, thereby reducing the gas production. High hydrate saturation is not conducive to depressurization because of the low effective permeability. After electric heating, the gas production increases significantly. High HBL thickness results in a higher gas production during depressurization, while in the electric heating stage, the gas production first increases and then remains unchanged with the increase of thickness, due to the limited heat supply. The comparison results of energy efficiency suggest that electric heating is more advantageous for hydrate sediments with low permeability, high porosity, high thermal conductivity, low specific heat capacity, high hydrate saturation and high HBL thickness. The findings in this work can provide a useful reference for evaluating the application of the LF-EHAD method in gas hydrate sediments.

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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 ◽

10.3390/en12224227 ◽

2019 ◽

Vol 12 (22) ◽

pp. 4227 ◽

Cited By ~ 1

Author(s):

Yi Wang ◽

Lei Zhan ◽

Jing-Chun Feng ◽

Xiao-Sen Li

Keyword(s):

Particle Size ◽

Alternative Energy ◽

Water Injection ◽

Gas Production ◽

Particle Migration ◽

Sand Production ◽

Hydrate Dissociation ◽

Hydrate Decomposition ◽

Heat Stimulation ◽

Sediment Deformation

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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Numerical studies of hydrate dissociation and gas production behavior in porous media during depressurization process

Journal of Natural Gas Chemistry ◽

10.1016/s1003-9953(11)60380-0 ◽

2012 ◽

Vol 21 (4) ◽

pp. 381-392 ◽

Cited By ~ 17

Author(s):

Xuke Ruan ◽

Mingjun Yang ◽

Yongchen Song ◽

Haifeng Liang ◽

Yanghui Li

Keyword(s):

Porous Media ◽

Gas Production ◽

Hydrate Dissociation ◽

Numerical Studies ◽

Production Behavior

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GAS PRODUCTION FROM THE HYDRATE RESERVOIR AT NEGATIVE TEMPERATURES

Oil and Gas Studies ◽

10.31660/0445-0108-2017-5-80-85 ◽

2017 ◽

pp. 80-85

Author(s):

N. G. Musakaev ◽

S. L. Borodin

Keyword(s):

Gas Production ◽

Filtration Flow ◽

Thomson Effect ◽

Real Gas ◽

Hydrate Decomposition ◽

Hydrate Reservoir ◽

Bottom Hole ◽

Adiabatic Cooling ◽

Hydrate Saturation ◽

The Mathematical Model

The mathematical model of the process of gas hydrate decomposition information to gas and ice is pro-posed. This model takes into account the non-isothermal filtration flow of gas, the adiabatic cooling effect, real gas properties, and Joule-Thomson effect. The influence of bottom hole pressure, permeability of a porous medium, and hydrate saturation on the rate of gas production from the reservoir initially saturated with methane and its hydrate was analyzed.

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Experimental Study on Gas Production from Methane Hydrate Bearing Sand by Depressurization

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.310.28 ◽

2013 ◽

Vol 310 ◽

pp. 28-32

Author(s):

Jian Ye Sun ◽

Yu Guang Ye ◽

Chang Ling Liu ◽

Jian Zhang

Keyword(s):

Experimental Study ◽

Methane Hydrate ◽

Hydrate Formation ◽

Gas Production ◽

Decomposition Kinetics ◽

Dissociation Process ◽

Hydrate Dissociation ◽

Gas Hydrate Formation ◽

Experimental Apparatus ◽

Hydrate Saturation

The simulate experiments of gas production from methane hydrates reservoirs was proceeded with an experimental apparatus. Especially, TDR technique was applied to represent the change of hydrate saturation in real time during gas hydrate formation and dissociation. In this paper, we discussed and explained material transformation during hydrate formation and dissociation. The hydrates form and grow on the top of the sediments where the sediments and gas connect firstly. During hydrates dissociation by depressurization, the temperatures and hydrate saturation presented variously in different locations of sediments, which shows that hydrates dissociate earlier on the surface and outer layer of the sediments than those of in inner. The regulation of hydrates dissociation is consistent with the law of decomposition kinetics. Furthermore, we investigated the depressurizing range influence on hydrate dissociation process.

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Numerical Studies of Methane Gas Production from Hydrate Decomposition by Depressurization in Porous Media

Energy Procedia ◽

10.1016/j.egypro.2017.03.310 ◽

2017 ◽

Vol 105 ◽

pp. 250-255 ◽

Cited By ~ 4

Author(s):

Minghao Yu ◽

Weizhong Li ◽

Mingjun Yang ◽

Lanlan Jiang ◽

Yongchen Song

Keyword(s):

Porous Media ◽

Gas Production ◽

Methane Gas ◽

Hydrate Decomposition ◽

Numerical Studies

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Investigating the Interaction Effects between Reservoir Deformation and Hydrate Dissociation in Hydrate-Bearing Sediment by Depressurization Method

Energies ◽

10.3390/en14030548 ◽

2021 ◽

Vol 14 (3) ◽

pp. 548

Author(s):

Lijia Li ◽

Xiaosen Li ◽

Yi Wang ◽

Chaozhong Qin ◽

Bo Li ◽

...

Keyword(s):

Production Process ◽

Coupling Model ◽

Effective Porosity ◽

Gas Production ◽

Water Production ◽

Reservoir Temperature ◽

Hydrate Dissociation ◽

Mechanical Coupling ◽

Hydrate Decomposition ◽

Hydrate Bearing Sediments

Natural gas hydrate (NGH) has been widely focused on having great potential for alternative energy. Numerous studies on gas production from hydrate-bearing sediments have been conducted in both laboratory and field. Since the strength of hydrate-bearing sediments depends on the saturation of NGH, the decomposition of NGH may cause the failure of sediments, then leading to reservoir deformation and other geological hazards. Plenty of research has shown that the reservoir deformation caused by hydrate decomposition is considerable. In order to investigate this, the influence of sediment deformation on the production of NGH, a fully coupled thermo-hydro-chemo-mechanical (THMC) model is established in this study. The interaction effects between reservoir deformation and hydrate dissociation are discussed by comparing the simulation results of the mechanical coupling and uncoupled models on the laboratory scale. Results show that obvious differences in behaviors between gas and water production are observed among these two models. Compared to the mechanical uncoupled model, the mechanical coupling model shows a significant compaction process when given a load equal to the initial pore pressure, which leads to a remarkable decrease of effective porosity and reservoir permeability, then delays the pore pressure drop rate and reduces the maximum gas production rate. It takes a longer time for gas production in the mechanical coupling model. Since the reservoir temperature is impacted by the comprehensive effects of the heat transfer from the boundary and the heat consumption of hydrate decomposition, the reduced maximum gas production rate and extended gas production process for the mechanical coupling model lead to the minimum reservoir temperature in the mechanical coupling model larger than that of the mechanical uncoupled model. The reduction of the effective porosity for the mechanical coupling model causes a larger cumulative water production. The results of this paper indicate that the reservoir deformation in the gas production process should be taken into account by laboratory and numerical methods to accurately predict the behaviors of gas production on the field scale.

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