Over the past 80 years,dozens of underground coal gasification(UCG)mine field tests have been carried out around the world.However,in the early days,only a small number of shallow UCG projects in the former Soviet Uni...Over the past 80 years,dozens of underground coal gasification(UCG)mine field tests have been carried out around the world.However,in the early days,only a small number of shallow UCG projects in the former Soviet Union achieved commercialised production.In this century,a few pilot projects in Australia also achieved short-term small-scale commercialised production using modern UCG technology.However,the commercialisation of UCG,especially medium-deep UCG projects with good development prospects but difficult underground engineering conditions,has not progressed smoothly around the world.Considering investment economy,a single gasifier must realise a high daily output and accumulated output,as well as hold a long gasification tunnel to control a large number of coal resources.However,a long gasification tunnel can easily be affected by blockages and failure,for which the remedial solutions are difficult and expensive,which greatly restricts the investment economy.The design of the underground gasifier determines the success or failure of UCG projects,and it also requires the related petroleum engineering technology.Combining the advantages of the linear horizontal well(L-CRIP)and parallel horizontal well(P-CRIP),this paper proposes a new design scheme for an“inclined ladder”underground gasifier.That is to say,the combination of the main shaft of paired P-CRIP and multiple branch horizontal well gasification tunnels is adopted to realise the control of a large number of coal resources in a single gasifier.The completion of the main shaft by well cementation is beneficial for maintaining the integrity of the main shaft and the stability of the main structure.The branch horizontal well is used as the gasification tunnel,but the length and number of retracting injection points are limited,effectively reducing the probability of blockage or failure.The branch horizontal well spacing can be adjusted flexibly to avoid minor faults and large cracks,which is conducive to increasing the resource utilisation rate.In addition,for multi-layer thin coal seams or ultra-thick coal seams,a multi-layer gasifier sharing vertical well sections can be deployed,thereby saving investment on the vertical well sections.Through preliminary analysis,this gasifier design scheme can be realised in engineering,making it suitable for largescale deployment where it can increase the resource utilisation rate and ensure stable and controllable operations.The new gasifier has outstanding advantages in investment economy,and good prospects for application in the commercial UCG projects of medium-deep coal seams.展开更多
Power line communication(PLC)provides intelligent electrical functions such as power quality measurement,fault surveys,and remote control of electrical network.Most of research works have been done in low voltage(LV)s...Power line communication(PLC)provides intelligent electrical functions such as power quality measurement,fault surveys,and remote control of electrical network.Most of research works have been done in low voltage(LV)scenario due to the fast development of in-home PLC.The aim of this paper is to evaluate the link-level performance of a medium voltage(MV)MIMO-OFDM communication system based on transmission link under underground power line channel.The MIMO channel is modeled as a modified multipath model in the presence of impulsive noise and background noise.We first perform a measurement on the practical MV MIMO channel parameters for a section of buried cable of 1 km long in Ganzhou city,Jiangxi province,China.Based on the measured channel,we design the frame structure based on an IEEE standard for broadband over power line networks[1]to support MV MIMO-OFDM transmission.According to designed frame structure,we design an encoder and a decoder for a dual binary tail-biting turbo code and optimize some key decoder parameters for low bit error rate performance.Finally,the link-level performance for both spatial multiplexing and spatial diversity are evaluated.Numeral results show that MV MIMO-OFDM is a promising approach to provide both high data rate and link reliability for PLC.展开更多
The most secure method in providing water in the dry and semi-dry regions is the use of underground water sources and due to over consumption of water aquifers capacities, most of fields and specially Imamzadeh Jafar ...The most secure method in providing water in the dry and semi-dry regions is the use of underground water sources and due to over consumption of water aquifers capacities, most of fields and specially Imamzadeh Jafar are faced with negative performance and balance, which threatens the land subsiding. The plateau with the annual raining of 438 millimeters has 169 deep and semi-deep wells with annual 36.68 million consumption and this issue has increased the research signification, in order to protect and relive the required water aquifers, there is a need to predict the underground water level accurately in different condition. In this research, by the use of balance equation and modflow software in Imamzadeh Jafar, water aquifer was analyzed within seven scenario. The underground water level evaluation for the short run periods for 2 years and middle term of 4 years and 12 years of long term was performed;and the results showed that the performance and balance of the plateau was increased due to increase of water consumption compared to the water aquifer quantity in the region that was negative. To the point that the 1, 3, 4, 5, 7 scenarios (minimum 0.17 and maximum -11.34) and 2, 6 scenarios in different timely periods show that the underground water saving volume is positive (minimum 3.64 and maximum 19.83).展开更多
【背景】在全球碳达峰碳中和背景下,可再生能源发展迅速,正逐步改变世界能源结构。但光伏和风电能源的间歇性和波动性特征容易导致电网频率波动和供电可靠性降低。压缩空气储能(compressed air energy storage,CAES)技术凭借其大容量、...【背景】在全球碳达峰碳中和背景下,可再生能源发展迅速,正逐步改变世界能源结构。但光伏和风电能源的间歇性和波动性特征容易导致电网频率波动和供电可靠性降低。压缩空气储能(compressed air energy storage,CAES)技术凭借其大容量、低成本优势,成为支撑绿色电网稳定运行的关键。【方法】通过对近年来国内外文献进行系统综述,梳理了CAES储气库地质评价理论与技术现状,对比分析了软岩硐室、多孔地层和硬岩硐室3类储气库的适用性、性能特征及关键技术瓶颈。【进展和展望】软岩硐室(盐岩层/废弃矿井)技术成熟但成本较高,需重点评估硐室稳定性与长期密封性;多孔地层(砂岩/废弃油气储层)储量大但气体控制难度高,需综合考虑圈闭条件、储层物性及断层封堵性;硬岩硐室(玄武岩/花岗岩)稳定性强但施工成本高,需优化裂缝控制与复合衬砌技术。当前CAES技术应用研究在地下储气库选址与评价、地质资源潜力评价和地下储层建模3方面进展显著,但仍面临以下问题:(1)盐穴依赖性强,废弃煤矿与硬岩硐室经济性不足,多孔地层非均质性影响储气效率;(2)地质资源潜力评价受限于数据精度和简化假设条件;(3)储层模拟缺乏多场耦合效应的考量。未来研究需从两方面突破:加强多孔地层储层孔隙结构和盖层的精细化研究,融合三维地震等技术,构建高精度地质模型;开发热−水−力多场耦合模型,并通过实验验证动态工况下的储层行为。研究结果为不同地质条件下CAES储气库的规模化应用提供了理论与技术参考。展开更多
文摘Over the past 80 years,dozens of underground coal gasification(UCG)mine field tests have been carried out around the world.However,in the early days,only a small number of shallow UCG projects in the former Soviet Union achieved commercialised production.In this century,a few pilot projects in Australia also achieved short-term small-scale commercialised production using modern UCG technology.However,the commercialisation of UCG,especially medium-deep UCG projects with good development prospects but difficult underground engineering conditions,has not progressed smoothly around the world.Considering investment economy,a single gasifier must realise a high daily output and accumulated output,as well as hold a long gasification tunnel to control a large number of coal resources.However,a long gasification tunnel can easily be affected by blockages and failure,for which the remedial solutions are difficult and expensive,which greatly restricts the investment economy.The design of the underground gasifier determines the success or failure of UCG projects,and it also requires the related petroleum engineering technology.Combining the advantages of the linear horizontal well(L-CRIP)and parallel horizontal well(P-CRIP),this paper proposes a new design scheme for an“inclined ladder”underground gasifier.That is to say,the combination of the main shaft of paired P-CRIP and multiple branch horizontal well gasification tunnels is adopted to realise the control of a large number of coal resources in a single gasifier.The completion of the main shaft by well cementation is beneficial for maintaining the integrity of the main shaft and the stability of the main structure.The branch horizontal well is used as the gasification tunnel,but the length and number of retracting injection points are limited,effectively reducing the probability of blockage or failure.The branch horizontal well spacing can be adjusted flexibly to avoid minor faults and large cracks,which is conducive to increasing the resource utilisation rate.In addition,for multi-layer thin coal seams or ultra-thick coal seams,a multi-layer gasifier sharing vertical well sections can be deployed,thereby saving investment on the vertical well sections.Through preliminary analysis,this gasifier design scheme can be realised in engineering,making it suitable for largescale deployment where it can increase the resource utilisation rate and ensure stable and controllable operations.The new gasifier has outstanding advantages in investment economy,and good prospects for application in the commercial UCG projects of medium-deep coal seams.
文摘Power line communication(PLC)provides intelligent electrical functions such as power quality measurement,fault surveys,and remote control of electrical network.Most of research works have been done in low voltage(LV)scenario due to the fast development of in-home PLC.The aim of this paper is to evaluate the link-level performance of a medium voltage(MV)MIMO-OFDM communication system based on transmission link under underground power line channel.The MIMO channel is modeled as a modified multipath model in the presence of impulsive noise and background noise.We first perform a measurement on the practical MV MIMO channel parameters for a section of buried cable of 1 km long in Ganzhou city,Jiangxi province,China.Based on the measured channel,we design the frame structure based on an IEEE standard for broadband over power line networks[1]to support MV MIMO-OFDM transmission.According to designed frame structure,we design an encoder and a decoder for a dual binary tail-biting turbo code and optimize some key decoder parameters for low bit error rate performance.Finally,the link-level performance for both spatial multiplexing and spatial diversity are evaluated.Numeral results show that MV MIMO-OFDM is a promising approach to provide both high data rate and link reliability for PLC.
文摘The most secure method in providing water in the dry and semi-dry regions is the use of underground water sources and due to over consumption of water aquifers capacities, most of fields and specially Imamzadeh Jafar are faced with negative performance and balance, which threatens the land subsiding. The plateau with the annual raining of 438 millimeters has 169 deep and semi-deep wells with annual 36.68 million consumption and this issue has increased the research signification, in order to protect and relive the required water aquifers, there is a need to predict the underground water level accurately in different condition. In this research, by the use of balance equation and modflow software in Imamzadeh Jafar, water aquifer was analyzed within seven scenario. The underground water level evaluation for the short run periods for 2 years and middle term of 4 years and 12 years of long term was performed;and the results showed that the performance and balance of the plateau was increased due to increase of water consumption compared to the water aquifer quantity in the region that was negative. To the point that the 1, 3, 4, 5, 7 scenarios (minimum 0.17 and maximum -11.34) and 2, 6 scenarios in different timely periods show that the underground water saving volume is positive (minimum 3.64 and maximum 19.83).
文摘【背景】在全球碳达峰碳中和背景下,可再生能源发展迅速,正逐步改变世界能源结构。但光伏和风电能源的间歇性和波动性特征容易导致电网频率波动和供电可靠性降低。压缩空气储能(compressed air energy storage,CAES)技术凭借其大容量、低成本优势,成为支撑绿色电网稳定运行的关键。【方法】通过对近年来国内外文献进行系统综述,梳理了CAES储气库地质评价理论与技术现状,对比分析了软岩硐室、多孔地层和硬岩硐室3类储气库的适用性、性能特征及关键技术瓶颈。【进展和展望】软岩硐室(盐岩层/废弃矿井)技术成熟但成本较高,需重点评估硐室稳定性与长期密封性;多孔地层(砂岩/废弃油气储层)储量大但气体控制难度高,需综合考虑圈闭条件、储层物性及断层封堵性;硬岩硐室(玄武岩/花岗岩)稳定性强但施工成本高,需优化裂缝控制与复合衬砌技术。当前CAES技术应用研究在地下储气库选址与评价、地质资源潜力评价和地下储层建模3方面进展显著,但仍面临以下问题:(1)盐穴依赖性强,废弃煤矿与硬岩硐室经济性不足,多孔地层非均质性影响储气效率;(2)地质资源潜力评价受限于数据精度和简化假设条件;(3)储层模拟缺乏多场耦合效应的考量。未来研究需从两方面突破:加强多孔地层储层孔隙结构和盖层的精细化研究,融合三维地震等技术,构建高精度地质模型;开发热−水−力多场耦合模型,并通过实验验证动态工况下的储层行为。研究结果为不同地质条件下CAES储气库的规模化应用提供了理论与技术参考。
