Based on the elastic theory of porous media,embedded discrete fracture model and finite volume method,and considering the micro-seepage mechanism of shale gas,a fully coupled seepage-geomechanical model suitable for f...Based on the elastic theory of porous media,embedded discrete fracture model and finite volume method,and considering the micro-seepage mechanism of shale gas,a fully coupled seepage-geomechanical model suitable for fractured shale gas reservoirs is established,the optimization method of refracturing timing is proposed,and the influencing factors of refracturing timing are analyzed based on the data from shale gas well in Fuling of Sichuan Basin.The results show that due to the depletion of formation pressure,the percentage of the maximum horizontal principal stress reversal area in the total area increases and then decreases with time.The closer the area is to the hydraulic fracture,the shorter the time for the peak of the stress reversal area percentage curve to appear,and the shorter the time for the final zero return(to the initial state).The optimum time of refracturing is affected by matrix permeability,initial stress difference and natural fracture approach angle.The larger the matrix permeability and initial stress difference is,the shorter the time for stress reversal area percentage curve to reach peak and return to the initial state,and the earlier the time to take refracturing measures.The larger the natural fracture approach angle is,the more difficult it is for stress reversal to occur near the fracture,and the earlier the optimum refracturing time is.The more likely the stress reversal occurs at the far end of the artificial fracture,the later the optimal time of refracturing is.Reservoirs with low matrix permeability have a rapid decrease in single well productivity.To ensure economic efficiency,measures such as shut-in or gas injection can be taken to restore the stress,and refracturing can be implemented in advance.展开更多
Institution of Modern Physics (IMP) has designed, fabricated and installed the first SRF cavity electropolishing system of China. It’s sized for 1.3 GHz SRF cavities, and also can works for multiple cell cavities wit...Institution of Modern Physics (IMP) has designed, fabricated and installed the first SRF cavity electropolishing system of China. It’s sized for 1.3 GHz SRF cavities, and also can works for multiple cell cavities with further upgrade of structure.展开更多
为了方便国内读者阅读和理解美国国家体能协会(NSCA)于2022年出版的NSCA′s Essentials of Sport Science,从出版背景、翻译中的若干问题、对我国训练科学与训练实践未来发展的启示3个方面撰写此书评。本书的推出是NSCA填补美国训练科...为了方便国内读者阅读和理解美国国家体能协会(NSCA)于2022年出版的NSCA′s Essentials of Sport Science,从出版背景、翻译中的若干问题、对我国训练科学与训练实践未来发展的启示3个方面撰写此书评。本书的推出是NSCA填补美国训练科学衰败留下的空白的一次主动作为,来自全球13个国家的51名专家基于最新研究成果和实践经验向读者呈现了近十年世界训练科学与训练实践的前沿动态。我国运动训练学亟待向训练科学迈进,加强学科的科学性、实践性、多学科性和应用性,更大程度实现体育多学科的融合、理论与实践的融合、科学与经验的融合、知识生产与转换的融合、行业建设与学科发展的融合,在竞技体育强国建设中勇挑重任、主动作为。展开更多
基金Supported by National Natural Science Foundation Joint Fund Project(U21B2071)National Natural Science Foundation of China(52174033)National Natural Science Youth Foundation of China(52304041).
文摘Based on the elastic theory of porous media,embedded discrete fracture model and finite volume method,and considering the micro-seepage mechanism of shale gas,a fully coupled seepage-geomechanical model suitable for fractured shale gas reservoirs is established,the optimization method of refracturing timing is proposed,and the influencing factors of refracturing timing are analyzed based on the data from shale gas well in Fuling of Sichuan Basin.The results show that due to the depletion of formation pressure,the percentage of the maximum horizontal principal stress reversal area in the total area increases and then decreases with time.The closer the area is to the hydraulic fracture,the shorter the time for the peak of the stress reversal area percentage curve to appear,and the shorter the time for the final zero return(to the initial state).The optimum time of refracturing is affected by matrix permeability,initial stress difference and natural fracture approach angle.The larger the matrix permeability and initial stress difference is,the shorter the time for stress reversal area percentage curve to reach peak and return to the initial state,and the earlier the time to take refracturing measures.The larger the natural fracture approach angle is,the more difficult it is for stress reversal to occur near the fracture,and the earlier the optimum refracturing time is.The more likely the stress reversal occurs at the far end of the artificial fracture,the later the optimal time of refracturing is.Reservoirs with low matrix permeability have a rapid decrease in single well productivity.To ensure economic efficiency,measures such as shut-in or gas injection can be taken to restore the stress,and refracturing can be implemented in advance.
文摘Institution of Modern Physics (IMP) has designed, fabricated and installed the first SRF cavity electropolishing system of China. It’s sized for 1.3 GHz SRF cavities, and also can works for multiple cell cavities with further upgrade of structure.
文摘为了方便国内读者阅读和理解美国国家体能协会(NSCA)于2022年出版的NSCA′s Essentials of Sport Science,从出版背景、翻译中的若干问题、对我国训练科学与训练实践未来发展的启示3个方面撰写此书评。本书的推出是NSCA填补美国训练科学衰败留下的空白的一次主动作为,来自全球13个国家的51名专家基于最新研究成果和实践经验向读者呈现了近十年世界训练科学与训练实践的前沿动态。我国运动训练学亟待向训练科学迈进,加强学科的科学性、实践性、多学科性和应用性,更大程度实现体育多学科的融合、理论与实践的融合、科学与经验的融合、知识生产与转换的融合、行业建设与学科发展的融合,在竞技体育强国建设中勇挑重任、主动作为。
