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Basic mathematical model for the normal black smoker system and the hydrothermal megaplume formation
A tube model to simulate the normal black smoker system has been built, where the Darcy flow equation, the Ergun equation and the turbulent pipe flow equation are used respectively to describe the dynamic process of different key areas in the hydrothermal circulation system. At the same time, a convection-diffuse Equation for the temperature field is used for describe the exchange of thermal energy and the law of temperature variation. Combining the above facts and using efficient mathematical algorithms and programming with the MatLab programming language, the variation curves of temperature, pressure and mass flow rate are determined, while also the dynamic heat equilibrium and pressure equilibrium within the black smoker system are analyzed. On the basis of the model of the normal black smoker system, a megaplume formation model is further built. For instance, the hydrothermal venting plume on the Juan de Fuca Ridge has been simulated and the simulation results are fairly consistent with Baker's imputed data in 1986. On the basis of the above productive simulation, a series of factors for megaplume formation and the effectiveness of the main parameters of the periodicity of the megaplume formation, temperature and the maximum mass flow rate are systematically discussed. Main conclusions are as follows: The normal black smoker system can evolve into a megaplum eruption. In fact, the passageway of the hydrothermal discharge is blocked by the hydrothermal sediments during the black smoker period, which leads to a hydrothermal fluid accumulation, rise of temperature and increase of buoyancy pressure under the seabed. After a period of 2~3 a, the megaplume hydrothermal eruption will occur when the increasing buoyancy pressure is high enough to crack the blockage (cap).Meanwhile, the temperature of the heat source must exceed 500 ℃, while the highest temperature of the eruption fluid may be high up to 413 ℃, which is fairly consistent with the surveying data.If the temperature of the heat source were to be higher than 500 ℃, then the critical period for the megaplume formation could be obviously curtailed to be less than 1 a, while the critical temperature and the maximum mass flow rate are nearly invariable. As the permeability increases, the maximum mass flow rate increases gradually close to a steady value. 相似文献
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华南四堡群是江南造山带的重要组成部分,是认识江南造山带弧沟体系的重要"窗口"。四堡群沉积地质学研究表明:1四堡群在黔东南地区总体构成一向上变浅的沉积序列:尧等组为深海-半深海相沉积;河村组浅海—滨岸相沉积。四堡群在桂北地区总体上也为一向上变浅的沉积序列:文通组为深海-半深海相沉积;鱼西组为浊积岩相沉积;2桂北地区四堡群碎屑岩系的29组沙纹层理(鲍马序列c段)的玫瑰花图解表明,古流向总体指向南,证明物源在其北侧;3四堡群砂岩骨架颗粒统计结果表明,其物源构造属性为岩浆弧;4基于以上研究,推测四堡群沉积于弧前盆地。 相似文献
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利用星间链路提升卫星导航系统性能已成为全球卫星导航系统的重要发展趋势之一。以GPS为代表的国外卫星导航系统都在积极发展星间链路。我国北斗卫星导航系统也将在新一代全球导航卫星上搭载星间链路,目前已开展在轨试验。通过国内外文献查阅和跟踪研究,系统梳理比较了GPS,GLONASS和Galileo三大全球系统已投入使用和正在论证的星间链路技术方案。在此基础上归纳了星间链路的发展特点与趋势:1)星间链路的设计不再局限于实现自主导航,更倾向于通过星地联合实现增强提升导航性能;2)星间链路的发展当前以高频段射频星间链路为主,激光星间链路是未来的发展方向;3)星间链路测距通信将主要采用时分多址体制。相关研究成果对我国北斗卫星导航系统星间链路的发展具有借鉴意义。 相似文献
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松科二井完钻井深为7108.88 m;完钻时停止钻井液循环后38 h,实测井底温度241℃。针对地层和温度情况,研究出了3种高温水基钻井液:抗温180℃的氯化钾聚磺钻井液;抗温230℃的高温聚合物钻井液;抗温250℃超高温的甲酸盐聚合物钻井液。其中,250℃钻井液以新型高温稳定剂为核心处理剂,凹凸棒土与钠膨润土黏土相,形成了新型甲酸盐聚合物体系。数据表明这几种钻井液具有良好的高温稳定性和较低的高温高压滤失量。工程现场的钻井液实验室结合取心作业特点,实时测试评价现场井浆的常规性能,同时监测井浆的抗温能力和高温流变性,根据实验数据和现场工况针对性的对井浆进行维护、调整,确保高温井段取心作业期间钻井液具有良好的性能。且在长时间裸眼、多次起下钻的工况下井壁稳定,测井、固井作业均得以顺利进行。各体系钻井液在转换时实现了安全平稳的过渡,极大的节约了成本。 相似文献