Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China Sea
The sediment of the hydrate reservoir in the Shenhu Area is mainly clayey silt. Its characteristic small particles and poor cementation challenge the quantification of the reservoir permeability during gas production. An accurate description of the seepage mechanism of the clayey-silt reservoir is t...
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doaj-3bec4e2a972f4c9db7d972797729c4372020-11-25T00:39:07ZengMDPI AGEnergies1996-10732019-09-011219368810.3390/en12193688en12193688Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China SeaCheng Lu0Yuxuan Xia1Xiaoxiao Sun2Hang Bian3Haijun Qiu4Hongfeng Lu5Wanjing Luo6Jianchao Cai7Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510075, ChinaInstitute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, ChinaGuangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510075, ChinaGuangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510075, ChinaGuangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510075, ChinaGuangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510075, ChinaSchool of Energy Resources, China University of Geosciences, Beijing 100083, ChinaInstitute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, ChinaThe sediment of the hydrate reservoir in the Shenhu Area is mainly clayey silt. Its characteristic small particles and poor cementation challenge the quantification of the reservoir permeability during gas production. An accurate description of the seepage mechanism of the clayey-silt reservoir is the basis, and also a difficulty, of effective development of gas in the South China Sea. In this study, four sets of water seepage experiments under different pressure gradients are carried out using the clayey-silt reservoir sediments, in which the fourth sample was subjected to computed tomographic (CT) scans. The experimental results shows that the clayey-silt reservoir has a compression of the pore structure and decreasing permeability with the increasing pressure gradient. CT images are used to show the reduction of pore spaces for fluid flow. When the pressure gradient is less than 3 MPa per meter, the pore structure of the reservoir has minor changes. When the pressure gradient is greater than this value, the pore structure of the reservoir will be quickly compressed. This leads to a rapid decrease in permeability, and the process of permeability reduction is irreversible. The decrease of permeability can be predicted directly by establishing a power law model with the change of porosity. Our experimental results preliminarily reveal the dynamic evolution law of pore structure and permeability of clayey-silt reservoir in the process of gas hydrate exploitation via depressurization. The permeability evolution law at various pressure gradients provides a scientific and reasonable basis of a productivity control system for clayey-silt gas hydrate in depressurized gas production.https://www.mdpi.com/1996-1073/12/19/3688clayey-silt porous medianatural gas hydrate reservoirpermeabilitymicro-ct |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Cheng Lu Yuxuan Xia Xiaoxiao Sun Hang Bian Haijun Qiu Hongfeng Lu Wanjing Luo Jianchao Cai |
spellingShingle |
Cheng Lu Yuxuan Xia Xiaoxiao Sun Hang Bian Haijun Qiu Hongfeng Lu Wanjing Luo Jianchao Cai Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China Sea Energies clayey-silt porous media natural gas hydrate reservoir permeability micro-ct |
author_facet |
Cheng Lu Yuxuan Xia Xiaoxiao Sun Hang Bian Haijun Qiu Hongfeng Lu Wanjing Luo Jianchao Cai |
author_sort |
Cheng Lu |
title |
Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China Sea |
title_short |
Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China Sea |
title_full |
Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China Sea |
title_fullStr |
Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China Sea |
title_full_unstemmed |
Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China Sea |
title_sort |
permeability evolution at various pressure gradients in natural gas hydrate reservoir at the shenhu area in the south china sea |
publisher |
MDPI AG |
series |
Energies |
issn |
1996-1073 |
publishDate |
2019-09-01 |
description |
The sediment of the hydrate reservoir in the Shenhu Area is mainly clayey silt. Its characteristic small particles and poor cementation challenge the quantification of the reservoir permeability during gas production. An accurate description of the seepage mechanism of the clayey-silt reservoir is the basis, and also a difficulty, of effective development of gas in the South China Sea. In this study, four sets of water seepage experiments under different pressure gradients are carried out using the clayey-silt reservoir sediments, in which the fourth sample was subjected to computed tomographic (CT) scans. The experimental results shows that the clayey-silt reservoir has a compression of the pore structure and decreasing permeability with the increasing pressure gradient. CT images are used to show the reduction of pore spaces for fluid flow. When the pressure gradient is less than 3 MPa per meter, the pore structure of the reservoir has minor changes. When the pressure gradient is greater than this value, the pore structure of the reservoir will be quickly compressed. This leads to a rapid decrease in permeability, and the process of permeability reduction is irreversible. The decrease of permeability can be predicted directly by establishing a power law model with the change of porosity. Our experimental results preliminarily reveal the dynamic evolution law of pore structure and permeability of clayey-silt reservoir in the process of gas hydrate exploitation via depressurization. The permeability evolution law at various pressure gradients provides a scientific and reasonable basis of a productivity control system for clayey-silt gas hydrate in depressurized gas production. |
topic |
clayey-silt porous media natural gas hydrate reservoir permeability micro-ct |
url |
https://www.mdpi.com/1996-1073/12/19/3688 |
work_keys_str_mv |
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