The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.U...The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area.The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area.The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography(X-CT)under high pressure and low temperature conditions.Results show that hydrates are mainly formed and distributed in the fractures with good connectivity.The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8%and 60.67%in two different core samples.This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples.Based on the field geological data and the experimental results,it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×1013 m3,with a resource abundance of 8.67×108 m3/km2.This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.展开更多
Natural gas hydrate,oil and gas were all found together in the Qilian Mountain permafrost area,northeast of Qinghai-Tibet Plateau,China.They are closely associated with each other in space,but whether they are in any ...Natural gas hydrate,oil and gas were all found together in the Qilian Mountain permafrost area,northeast of Qinghai-Tibet Plateau,China.They are closely associated with each other in space,but whether they are in any genetic relations are unknown yet.In this paper,a hydrocarbon gas-generation series,gas-fluid migration series and hydrocarbon gas-accumulation series are analyzed to probe the spatial,temporal and genetic relationships among natural natural gas hydrate,oil and gas.The subsequent results show that natural gas hydrate,oil and gas actually form a natural gas hydrate-oil-gas system.Based on the Middle Jurassic and the Upper Triassic hydrocarbon gas-generation series,it is divided into four major sub-systems in the study area:(1)A conventional Upper Triassic gas-bearing sub-system with peak hydrocarbon gas-generation in the late Middle Jurassic;(2)a conventional Middle Jurassic oil-bearing sub-system with low to mature hydrocarbon gas-generation in the late Middle Jurassic;(3)a natural gas hydrate sub-system with main gas source from the Upper Triassic gas-bearing sub-system and minor gas source from the Middle Jurassic oil-bearing sub-system as well as little gas source from the Middle Jurassic coal-bed gas and the microbial gas;(4)a shallower gas sub-system with microbial alteration of the main gas source from the Upper Triassic gas-bearing sub-system.This natural gas hydrate-oil-gas system and its sub-systems are not only theoretical but also practical,and thus they will play an important role in the further exploration of natural gas hydrate,oil and gas,even other energy resources in the study area.展开更多
Qilian Mountain permafrost, with area about 10×10^4 km2, locates in the north of Qinghai- Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drill...Qilian Mountain permafrost, with area about 10×10^4 km2, locates in the north of Qinghai- Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008-2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK-1, DK-2 and DK-3. Gas hydrate is hosted under permafrost zone in the 133-396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydratebearing cores strongly bubble in the water. Gas-bubble and water-drop are emitted from the hydratebearing cores and then characteristic of honeycombed structure is left. The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal-bed methane origin etc.展开更多
The gas hydrates in the permafrost region of Qilian Mountain are characterized by low latitude, thin thickness, shallow burial depth, abundant coal seams, high contents of heavy hydrocarbons and multiple sets of sourc...The gas hydrates in the permafrost region of Qilian Mountain are characterized by low latitude, thin thickness, shallow burial depth, abundant coal seams, high contents of heavy hydrocarbons and multiple sets of source rocks. Up to date, the source of gas or the main source rocks of the Mull gas hydrates have remained unclear.展开更多
As an important part of gas hydrates, light hydrocarbons （LHs）, especially C5 to C7 hydrocarbons with various monomer compounds, provide a wide variety of geological and geochemical information, which have received ...As an important part of gas hydrates, light hydrocarbons （LHs）, especially C5 to C7 hydrocarbons with various monomer compounds, provide a wide variety of geological and geochemical information, which have received much attention from organic geochemists and petroleum geologists.展开更多
Objective As a new type of gas hydrates,the natural gas hydrates in the perfost region of the Qilian Mountains are characterized by their shallow burial depth,welldeveloped coal seam,high content of heavy hydrocarbons...Objective As a new type of gas hydrates,the natural gas hydrates in the perfost region of the Qilian Mountains are characterized by their shallow burial depth,welldeveloped coal seam,high content of heavy hydrocarbons and multiple sets of mature and over-mature source rocks.Gas sources of these gas hydrates in the study area include coal-type gas and oil-type gas.展开更多
基金the financial support of the National Natural Science Foundation of China(42176212,41976074 and 41302034)the Marine S&T Fund of Shandong Province for Laoshan Laboratory(2021QNLM020002)the Marine Geological Survey Program(DD20221704)。
文摘The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area.The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area.The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography(X-CT)under high pressure and low temperature conditions.Results show that hydrates are mainly formed and distributed in the fractures with good connectivity.The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8%and 60.67%in two different core samples.This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples.Based on the field geological data and the experimental results,it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×1013 m3,with a resource abundance of 8.67×108 m3/km2.This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.
基金This work was supported by the projects of China Geological Survey(DD20160223,DD20190102).
文摘Natural gas hydrate,oil and gas were all found together in the Qilian Mountain permafrost area,northeast of Qinghai-Tibet Plateau,China.They are closely associated with each other in space,but whether they are in any genetic relations are unknown yet.In this paper,a hydrocarbon gas-generation series,gas-fluid migration series and hydrocarbon gas-accumulation series are analyzed to probe the spatial,temporal and genetic relationships among natural natural gas hydrate,oil and gas.The subsequent results show that natural gas hydrate,oil and gas actually form a natural gas hydrate-oil-gas system.Based on the Middle Jurassic and the Upper Triassic hydrocarbon gas-generation series,it is divided into four major sub-systems in the study area:(1)A conventional Upper Triassic gas-bearing sub-system with peak hydrocarbon gas-generation in the late Middle Jurassic;(2)a conventional Middle Jurassic oil-bearing sub-system with low to mature hydrocarbon gas-generation in the late Middle Jurassic;(3)a natural gas hydrate sub-system with main gas source from the Upper Triassic gas-bearing sub-system and minor gas source from the Middle Jurassic oil-bearing sub-system as well as little gas source from the Middle Jurassic coal-bed gas and the microbial gas;(4)a shallower gas sub-system with microbial alteration of the main gas source from the Upper Triassic gas-bearing sub-system.This natural gas hydrate-oil-gas system and its sub-systems are not only theoretical but also practical,and thus they will play an important role in the further exploration of natural gas hydrate,oil and gas,even other energy resources in the study area.
文摘Qilian Mountain permafrost, with area about 10×10^4 km2, locates in the north of Qinghai- Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008-2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK-1, DK-2 and DK-3. Gas hydrate is hosted under permafrost zone in the 133-396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydratebearing cores strongly bubble in the water. Gas-bubble and water-drop are emitted from the hydratebearing cores and then characteristic of honeycombed structure is left. The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal-bed methane origin etc.
基金financially supported by the National Natural Science Foundation of China(grant No.41273066)
文摘The gas hydrates in the permafrost region of Qilian Mountain are characterized by low latitude, thin thickness, shallow burial depth, abundant coal seams, high contents of heavy hydrocarbons and multiple sets of source rocks. Up to date, the source of gas or the main source rocks of the Mull gas hydrates have remained unclear.
基金financially supported by the National Natural Science Foundation of China(grant No.41273066)
文摘As an important part of gas hydrates, light hydrocarbons （LHs）, especially C5 to C7 hydrocarbons with various monomer compounds, provide a wide variety of geological and geochemical information, which have received much attention from organic geochemists and petroleum geologists.
基金financially supported by the National Science Foundation of china(Grant No.41273066)
文摘Objective As a new type of gas hydrates,the natural gas hydrates in the perfost region of the Qilian Mountains are characterized by their shallow burial depth,welldeveloped coal seam,high content of heavy hydrocarbons and multiple sets of mature and over-mature source rocks.Gas sources of these gas hydrates in the study area include coal-type gas and oil-type gas.
