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

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.

scholarly journals Gas hydrate in-situ formation and dissociation in clayey-silt sediments: An investigation by low-field NMR

2020 ◽  
pp. 014459872097415
Author(s):  
Xiaoxiao Sun ◽  
Xuwen Qin ◽  
Hongfeng Lu ◽  
Jingli Wang ◽  
Jianchun Xu ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Hydrate Formation ◽  
Dissociation Process ◽  
Hydrate Dissociation ◽  
Hydrate Reservoir ◽  
Low Field ◽  
Gas Hydrate Formation ◽  
Clayey Silt ◽  
Hydrate Saturation ◽  
Low Field Nmr

The hydrate reservoir in the Shenhu Area of the South China Sea is a typical clayey-silt porous media with high clay mineral content and poor cementation, in which gas hydrate formation and dissociation characteristics are unclear. In this study, the CO2 hydrate saturation, growth rate, and permeability were studied in sandstone, artificial samples, and clayey-silt sediments using a custom-built measurement apparatus based on the low-field NMR technique. Results show that the T2 spectra amplitudes decrease with the hydrate formation and increase with the dissociation process. For the artificial samples and Shenhu sediments, the CO2 hydrate occupies larger pores first and the homogeneity of the sandstone pores becomes poor. Meanwhile, compared with the clayey-silt sediments, CO2 hydrate is easier to form and with higher hydrate saturation for the sandstone and artificial samples. In hydrate dissociation process, there exists a protection mechanism, i.e. the dissociation near the center of hydrates grain is suppressed when gas pressure drops suddenly and quickly. For permeability of those samples, it decreased with hydrate forms, and increases with hydrate dissociation. Meanwhile, with the same hydrate saturation, permeability is higher in hydrate formation than in dissociation.

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

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.

Experimental Study on the Effect of Gas Hydrate Content on Heat Transfer

2015 ◽  
Author(s):  
Remi-Erempagamo T. Meindinyo ◽  
Runar Bøe ◽  
Thor Martin Svartås ◽  
Silje Bru
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Ethylene Oxide ◽  
Deep Water ◽  
Gas Hydrate ◽  
Atmospheric Pressure ◽  
Methane Hydrate ◽  
Hydrate Formation ◽  
Equilibrium Temperature ◽  
Gas Hydrate Formation

Gas hydrates are the foremost flow assurance issue in deep water operations. Since heat transfer is a limiting factor in gas hydrate formation processes, a better understanding of its relation to hydrate formation is important. This work presents findings from experimental study of the effect of gas hydrate content on heat transfer through a cylindrical wall. The experiments were carried out at temperature conditions similar to those encountered in flowlines in deep water conditions. Experiments were conducted on methane hydrate, Tetrahydrofuran hydrate, and ethylene oxide hydrate respectively in stirred cylindrical high pressure autoclave cells. Methane hydrate was formed at 90 bars (pressure), and 8°C, followed by a cooling/heating cycle in the range of 8°C → 4°C → 8°C. Tetrahydrofuran (THF) and ethylene oxide (EO) hydrates were formed at atmospheric pressure and system temperature of 1°C in contact with atmospheric air. This was followed by a heating/cooling cycle within the range of 1°C → 4°C → 1°C, since the hydrate equilibrium temperature of THF hydrate is 4.98°C in contact with air at atmospheric pressure. The experimental conditions of the latter hydrate formers were more controlled, given that both THF and EO are miscible with water. We found in all cases a general trend of decreasing heat transfer coefficient of the cell content with increasing concentration of hydrate in the cell, indicating that hydrate formation creates a heat transfer barrier. The hydrate equilibrium temperature seemed to change with a change in the stoichiometric concentration of THF and EO. While the methane hydrate cooling/heating cycles were performed under quiescent conditions, the effect of stirring was investigated for the latter hydrate formers.

The Characteristic of Hydrate Exploitation by Depressurization

2013 ◽  
Author(s):  
Weixin Pang ◽  
Qingping Li ◽  
Xichong Yu ◽  
Fujie Sun ◽  
Gang Li
Keyword(s):  
South China Sea ◽  
South China ◽  
Methane Hydrate ◽  
Gas Production ◽  
Shenhu Area ◽  
Hydrate Dissociation ◽  
Hydrate Reservoir ◽  
Hydrate Saturation ◽  
Porosity And Permeability ◽  
Hydrate Deposit

According to the schematic and properties of a methane hydrate deposit in Shenhu Area of South China Sea in China, the characteristic of hydrate dissociation, water and gas production were simulated with a depressurization method. The effect of hydrate saturation, porosity and permeability et al. on hydrate dissociation was studied, the key controlling factor and difficulty of gas production from hydrate reservoir by depressurization was confirmed.

Geomechanical Responses During Gas Hydrate Production Induced by Depressurization

2016 ◽  
Author(s):  
Ah-Ram Kim ◽  
Gye-Chun Cho ◽  
Joo-Yong Lee ◽  
Se-Joon Kim
Keyword(s):  
Methane Hydrate ◽  
Fossil Fuel ◽  
Gas Production ◽  
Field Scale ◽  
Production Well ◽  
Physical Processes ◽  
Hydrate Dissociation ◽  
Thermal Changes ◽  
New Energy ◽  
Hydrate Bearing Sediments

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.

scholarly journals Numerical simulation of CH4 hydrate formation in fractures

2018 ◽  
Vol 36 (5) ◽  
pp. 1279-1294 ◽  
Author(s):  
Sheng-Li Li ◽  
You-Hong Sun ◽  
Kai Su ◽  
Wei Guo ◽  
You-Hai Zhu
Keyword(s):  
Methane Hydrate ◽  
Hydrate Formation ◽  
Growth Behavior ◽  
Fractured Media ◽  
Initial Condition ◽  
Insulation Layer ◽  
Hydrate Dissociation ◽  
Fracture Size ◽  
The Media ◽  
Gas Supply

Fracture-hosted methane hydrate deposits exist at many sites worldwide. The growth behavior of CH4 hydrate in fractured media was simulated by TOUGH + HYDRATE (T + H) code. The effects of fracture size, initial condition, and salinity on the growth behavior of hydrate in fractures were investigated. In general, the hydrate layer grew from the two ends and gradually covered on the surface of the fracture. With the formation of hydrate in fractures, the temperature increased sharply since the hydrate acted as a thermal insulation layer. In longer fractures, fast growth of hydrate at the ends of the fracture led to the formation of hydrate plugs with high saturation (called as stopper). In narrower fractures, hydrate dissociation occurred in the middle of the fracture during hydrate growing in the whole fracture due to the cutoff of gas supply by the stopper at the ends. At a low initial subcooling, hydrate formed both on the surface and in the micropores of the media, which was different from that at higher subcooling. In salt solution, the formation of hydrate stopper was inhibited by the salt-removing effect of hydrate formation and the growth of hydrate was more sustainable.

scholarly journals Experimental Study on Methane Hydrate Dissociation by Depressurization in Porous Sediments

Energies ◽  
2012 ◽  
Vol 5 (2) ◽  
pp. 518-530 ◽  
Author(s):  
Lijun Xiong ◽  
Xiaosen Li ◽  
Yi Wang ◽  
Chungang Xu
Keyword(s):  
Experimental Study ◽  
Methane Hydrate ◽  
Hydrate Dissociation ◽  
Porous Sediments
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