The typical characteristics of shale gas and the enrichment differences show that some shale gases are insufficiently explained by the existing continuous enrichment mode. These shale gases include the Wufeng–Longmax...The typical characteristics of shale gas and the enrichment differences show that some shale gases are insufficiently explained by the existing continuous enrichment mode. These shale gases include the Wufeng–Longmaxi shale gas in the Jiaoshiba and Youyang Blocks, the Lewis shale gas in the San Juan Basin. Further analysis reveals three static subsystems（hydrocarbon source rock, gas reservoirs and seal formations） and four dynamic subsystems（tectonic evolution, sedimentary sequence, diagenetic evolution and hydrocarbon-generation history） in shale-gas enrichment systems. Tectonic evolution drives the dynamic operation of the whole shale-gas enrichment system. The shale-gas enrichment modes controlled by tectonic evolution are classifiable into three groups and six subgroups. Group I modes are characterized by tectonically controlled hydrocarbon source rock, and include continuous in-situ biogenic shale gas（Ⅰ_1） and continuous in-situ thermogenic shale gas（Ⅰ_2）. Group Ⅱ modes are characterized by tectonically controlled gas reservoirs, and include anticline-controlled reservoir enrichment（Ⅱ_1） and fracture-controlled reservoir enrichment（Ⅱ_2）. Group Ⅲ modes possess tectonically controlled seal formations, and include faulted leakage enrichment（Ⅲ_1） and eroded residual enrichment（Ⅲ_2）. In terms of quantity and exploitation potential, Ⅰ_1 and Ⅰ_2 are the best shale-gas enrichment modes, followed by Ⅱ_1 and Ⅱ_2. The least effective modes are Ⅲ_1 and Ⅲ_2. The categorization provides a different perspective for deep shale-gas exploration.展开更多
Lead is a potentially harmful element that has caused serious environmental pollution during its mining and use along with serious human health problems.This study assessed lead in Chinese coals based on published lit...Lead is a potentially harmful element that has caused serious environmental pollution during its mining and use along with serious human health problems.This study assessed lead in Chinese coals based on published literature,with a particular focus on data reported since 2004.The analysis included 9447 individual samples from 103 coalfields or mines in 28 provinces in China.The arithmetic mean content of lead in the studied coals was 15.0μg/g.Considering the coal reserves,the weighted-average lead concentration in Chinese coals was calculated to be 19.6μg/g.Lead was significantly enriched in the coals from Henan Province and enriched in the coals from the Tibet Autonomous Region.The coals from Tibet–Western Yunnan and the southern areas of China had elevated lead concentrations.Sulfides are the primary hosts of lead in Chinese coals,although other hosts include silicates,organic matter,carbonates,and other minerals.Source rocks in the sediment-source region and marine environments may be the most significant factors contributing to lead enrichment in Chinese coals.Hydrothermal fluids and peat-forming plants also contribute to lead enrichment in some Chinese coals.展开更多
To evaluate the comprehensive exploitation and utilization values of coal resources in Baise basin of Guangxi, the Paleogene coal of Linchang coal mine were sampled and studied. The enrichment characteristics, occurre...To evaluate the comprehensive exploitation and utilization values of coal resources in Baise basin of Guangxi, the Paleogene coal of Linchang coal mine were sampled and studied. The enrichment characteristics, occurrence modes, and geochemical origin of valuable trace elements in coal were studied by using X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS), polarizing microscope, X-ray fluorescence spectrometry (XRF), inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectrometry (AFS). The results reveal that Linchang coal is ultra-low calorific value lignite with high ash, medium sulfur, medium-high moisture and medium volatilization. The minerals are mainly composed of illite, kaolinite, quartz, pyrite, siderite, bassanite, anhydrite and magnesium-containing calcite. Compared with average values for world low-rank coals, the contents of valuable trace elements in Linchang coal are higher on the whole, which is characterized by the high enrichment o<span>f U, the enrichment of elements Li, V and Ag, and the slight enrichment of</span> elements Be, Ga and Se. Lithium, V, Ga and Ag mainly occur in clay minerals including illite and kaolinite, and part of V is related to organic matter. Th<span>e carriers of Be in coal are clay minerals and organic matter. Selenium is </span>mainly combined with organic matter and a small amount exists in pyrite. Uranium is primarily organically bound in coal. The enrichment of valuable trace elements in Linchang coal is influenced by the sedimentary source, coal<span>-forming environment, underground circulating water and geological structure. The sedimentary environment of the coal seam is an acid-reduced terrestrial peat swamp, and the source is Triassic sedimentary rocks weathered f</span>rom feldspathic volcanic rocks around Baise basin.展开更多
Four different pulverized coals have been used to study the effects of oxygen concentration on combustion characteristics under different enriched-oxygen conditions by entrained flow reactor experiments. The results s...Four different pulverized coals have been used to study the effects of oxygen concentration on combustion characteristics under different enriched-oxygen conditions by entrained flow reactor experiments. The results show that: with the increase of oxygen concentration, the ignition temperature of four coals greatly decreases and the low volatile coals decrease faster; with the increase of oxygen concentration, the ignition mode of pulverized coal has an obviously transformation from homogeneous ignition to heterogeneous ignition, and the corresponding oxygen concentrations are about 40% and 50%-60% respectively for bituminous coal and lignite, and both about 30% for lean coal and anthracite; with the increase of oxygen concentration, the optimal pulverized coal concentrations of bituminous coal and lignite increase firstly and then decrease, but for lean coal and anthracite, the optimal pulverized coal concentrations decrease slowly with the increase of oxygen concentration.展开更多
基金supported by the National Basic Research Program of China(grant No.2014CB239205)the sub-project of the National Science and Technology Major Project(grant No.2017ZX05035003)
文摘The typical characteristics of shale gas and the enrichment differences show that some shale gases are insufficiently explained by the existing continuous enrichment mode. These shale gases include the Wufeng–Longmaxi shale gas in the Jiaoshiba and Youyang Blocks, the Lewis shale gas in the San Juan Basin. Further analysis reveals three static subsystems（hydrocarbon source rock, gas reservoirs and seal formations） and four dynamic subsystems（tectonic evolution, sedimentary sequence, diagenetic evolution and hydrocarbon-generation history） in shale-gas enrichment systems. Tectonic evolution drives the dynamic operation of the whole shale-gas enrichment system. The shale-gas enrichment modes controlled by tectonic evolution are classifiable into three groups and six subgroups. Group I modes are characterized by tectonically controlled hydrocarbon source rock, and include continuous in-situ biogenic shale gas（Ⅰ_1） and continuous in-situ thermogenic shale gas（Ⅰ_2）. Group Ⅱ modes are characterized by tectonically controlled gas reservoirs, and include anticline-controlled reservoir enrichment（Ⅱ_1） and fracture-controlled reservoir enrichment（Ⅱ_2）. Group Ⅲ modes possess tectonically controlled seal formations, and include faulted leakage enrichment（Ⅲ_1） and eroded residual enrichment（Ⅲ_2）. In terms of quantity and exploitation potential, Ⅰ_1 and Ⅰ_2 are the best shale-gas enrichment modes, followed by Ⅱ_1 and Ⅱ_2. The least effective modes are Ⅲ_1 and Ⅲ_2. The categorization provides a different perspective for deep shale-gas exploration.
基金This research was supported by National Natural Science Foundation of China(Grant No.4197217,41472136)Special thanks are given to Shifeng Dai and two anonymous reviewers for their useful suggestions and comments.
文摘Lead is a potentially harmful element that has caused serious environmental pollution during its mining and use along with serious human health problems.This study assessed lead in Chinese coals based on published literature,with a particular focus on data reported since 2004.The analysis included 9447 individual samples from 103 coalfields or mines in 28 provinces in China.The arithmetic mean content of lead in the studied coals was 15.0μg/g.Considering the coal reserves,the weighted-average lead concentration in Chinese coals was calculated to be 19.6μg/g.Lead was significantly enriched in the coals from Henan Province and enriched in the coals from the Tibet Autonomous Region.The coals from Tibet–Western Yunnan and the southern areas of China had elevated lead concentrations.Sulfides are the primary hosts of lead in Chinese coals,although other hosts include silicates,organic matter,carbonates,and other minerals.Source rocks in the sediment-source region and marine environments may be the most significant factors contributing to lead enrichment in Chinese coals.Hydrothermal fluids and peat-forming plants also contribute to lead enrichment in some Chinese coals.
文摘To evaluate the comprehensive exploitation and utilization values of coal resources in Baise basin of Guangxi, the Paleogene coal of Linchang coal mine were sampled and studied. The enrichment characteristics, occurrence modes, and geochemical origin of valuable trace elements in coal were studied by using X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS), polarizing microscope, X-ray fluorescence spectrometry (XRF), inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectrometry (AFS). The results reveal that Linchang coal is ultra-low calorific value lignite with high ash, medium sulfur, medium-high moisture and medium volatilization. The minerals are mainly composed of illite, kaolinite, quartz, pyrite, siderite, bassanite, anhydrite and magnesium-containing calcite. Compared with average values for world low-rank coals, the contents of valuable trace elements in Linchang coal are higher on the whole, which is characterized by the high enrichment o<span>f U, the enrichment of elements Li, V and Ag, and the slight enrichment of</span> elements Be, Ga and Se. Lithium, V, Ga and Ag mainly occur in clay minerals including illite and kaolinite, and part of V is related to organic matter. Th<span>e carriers of Be in coal are clay minerals and organic matter. Selenium is </span>mainly combined with organic matter and a small amount exists in pyrite. Uranium is primarily organically bound in coal. The enrichment of valuable trace elements in Linchang coal is influenced by the sedimentary source, coal<span>-forming environment, underground circulating water and geological structure. The sedimentary environment of the coal seam is an acid-reduced terrestrial peat swamp, and the source is Triassic sedimentary rocks weathered f</span>rom feldspathic volcanic rocks around Baise basin.
文摘Four different pulverized coals have been used to study the effects of oxygen concentration on combustion characteristics under different enriched-oxygen conditions by entrained flow reactor experiments. The results show that: with the increase of oxygen concentration, the ignition temperature of four coals greatly decreases and the low volatile coals decrease faster; with the increase of oxygen concentration, the ignition mode of pulverized coal has an obviously transformation from homogeneous ignition to heterogeneous ignition, and the corresponding oxygen concentrations are about 40% and 50%-60% respectively for bituminous coal and lignite, and both about 30% for lean coal and anthracite; with the increase of oxygen concentration, the optimal pulverized coal concentrations of bituminous coal and lignite increase firstly and then decrease, but for lean coal and anthracite, the optimal pulverized coal concentrations decrease slowly with the increase of oxygen concentration.
