China’s helium resource is highly dependent on overseas imports.Organic-rich and U/Th-rich shale reservoirs generally contain helium,and although the helium content is low,the total reserve is large.Therefore,the eff...China’s helium resource is highly dependent on overseas imports.Organic-rich and U/Th-rich shale reservoirs generally contain helium,and although the helium content is low,the total reserve is large.Therefore,the effective development and utilisation of shale-type helium resources is a realistic way to improve the security of helium resources in China.In this study,the generation mechanism,helium source and content,migration modes and pathways,controlling factors of enrichment,distribution pattern,and resource potential of the helium were analysed,using the Wufeng-Longmaxi shale in the Sichuan Basin and its periphery.Furthermore,countermeasures were proposed for shale-type helium exploration and development.The results show that the Wufeng-Longmaxi shale has a high content of U and Th and a good ability to generate helium.The helium is generated by a typical crustal source of helium and is characterised by self-generation,self-storage,and wide distribution.The helium resource potential is a product of its content and the resources of the associated natural gas.The continuous supply of helium and effective preservation are the main geological factors that control the enrichment of shale-type helium.The preliminary evaluation results show that the reserves of helium in proven shale gas reserves are 10.8×10^(8)m^(3)in the Sichuan Basin and its periphery,where the extra-large helium fields are likely to be discovered.Additionally,0.0912×10^(8)m^(3)of helium was produced,along with the annual production of shale gas.To avoid the waste of helium and to improve the self-supply ability,it is suggested that research on the resource potential,enrichment mechanism,and distribution pattern of shale-type helium should be carried out as soon as possible,and helium extraction techniques for helium-bearing natural gas should be studied.展开更多
The stability of underground abandoned gypsum mines is dependent on the gypsum pillar's strength,and most abandoned mines are in a fully saturated condition. Moisture affects the strength of gypsum and is therefor...The stability of underground abandoned gypsum mines is dependent on the gypsum pillar's strength,and most abandoned mines are in a fully saturated condition. Moisture affects the strength of gypsum and is therefore commonly measured when testing rock strength. For most rocks, this is a simple task of weighing the rock's mass before and after oven-heating at a specified temperature and duration. For natural gypsum, however, this is not a straightforward process. Heating natural gypsum can result in dehydration and transformation of gypsum to hemihydrate and anhydrite, thus changing the physical characteristics of the gypsum such as its particle density which in turn affects the moisture content and strength measurements. To prevent transformation when determining the moisture content of gypsum,the American Society for Testing Materials(ASTM) recommends lowering the drying temperature from 110℃ to 60℃ . To investigate the temperature at which gypsum transforms to hemihydrate, we used a helium pycnometer to measure the particle densities of gypsum, hemihydrate and anhydrite. In this research, we suggest that a higher drying temperature of 80℃ can be used for drying gypsum without transforming gypsum to hemihydrate. Further, preparing saturated samples for mechanical testing,which is required in stability analyses of abandoned mines, is challenging due to the dissolution of gypsum when placed in water. To address this problem, we investigated the following methods to saturate gypsum cores taking into account the solubility of gypsum:(1) water immersion,(2) vacuum saturation, and(3) improved vacuum saturation. The research indicates that all the three methods are acceptable but they should be conducted using a saturated gypsum-water solution to minimize dissolution. Further, the research found that the improved vacuum saturation method saturated the test samples within 24 h, while duration of 30 h was required for the other two methods.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42141021,41872124&42130803).
文摘China’s helium resource is highly dependent on overseas imports.Organic-rich and U/Th-rich shale reservoirs generally contain helium,and although the helium content is low,the total reserve is large.Therefore,the effective development and utilisation of shale-type helium resources is a realistic way to improve the security of helium resources in China.In this study,the generation mechanism,helium source and content,migration modes and pathways,controlling factors of enrichment,distribution pattern,and resource potential of the helium were analysed,using the Wufeng-Longmaxi shale in the Sichuan Basin and its periphery.Furthermore,countermeasures were proposed for shale-type helium exploration and development.The results show that the Wufeng-Longmaxi shale has a high content of U and Th and a good ability to generate helium.The helium is generated by a typical crustal source of helium and is characterised by self-generation,self-storage,and wide distribution.The helium resource potential is a product of its content and the resources of the associated natural gas.The continuous supply of helium and effective preservation are the main geological factors that control the enrichment of shale-type helium.The preliminary evaluation results show that the reserves of helium in proven shale gas reserves are 10.8×10^(8)m^(3)in the Sichuan Basin and its periphery,where the extra-large helium fields are likely to be discovered.Additionally,0.0912×10^(8)m^(3)of helium was produced,along with the annual production of shale gas.To avoid the waste of helium and to improve the self-supply ability,it is suggested that research on the resource potential,enrichment mechanism,and distribution pattern of shale-type helium should be carried out as soon as possible,and helium extraction techniques for helium-bearing natural gas should be studied.
文摘The stability of underground abandoned gypsum mines is dependent on the gypsum pillar's strength,and most abandoned mines are in a fully saturated condition. Moisture affects the strength of gypsum and is therefore commonly measured when testing rock strength. For most rocks, this is a simple task of weighing the rock's mass before and after oven-heating at a specified temperature and duration. For natural gypsum, however, this is not a straightforward process. Heating natural gypsum can result in dehydration and transformation of gypsum to hemihydrate and anhydrite, thus changing the physical characteristics of the gypsum such as its particle density which in turn affects the moisture content and strength measurements. To prevent transformation when determining the moisture content of gypsum,the American Society for Testing Materials(ASTM) recommends lowering the drying temperature from 110℃ to 60℃ . To investigate the temperature at which gypsum transforms to hemihydrate, we used a helium pycnometer to measure the particle densities of gypsum, hemihydrate and anhydrite. In this research, we suggest that a higher drying temperature of 80℃ can be used for drying gypsum without transforming gypsum to hemihydrate. Further, preparing saturated samples for mechanical testing,which is required in stability analyses of abandoned mines, is challenging due to the dissolution of gypsum when placed in water. To address this problem, we investigated the following methods to saturate gypsum cores taking into account the solubility of gypsum:(1) water immersion,(2) vacuum saturation, and(3) improved vacuum saturation. The research indicates that all the three methods are acceptable but they should be conducted using a saturated gypsum-water solution to minimize dissolution. Further, the research found that the improved vacuum saturation method saturated the test samples within 24 h, while duration of 30 h was required for the other two methods.
