API 6A井口装置及采油树设备当应用于特殊或恶劣工况,如用于海洋钻井平台钻井作业、极地环境钻井作业及压裂增产作业时,需考虑井口装置及采油树设备的性能等级、可靠性和使用寿命等因素,确保设备在额定工作压力、额定工作温度以及高含...API 6A井口装置及采油树设备当应用于特殊或恶劣工况,如用于海洋钻井平台钻井作业、极地环境钻井作业及压裂增产作业时,需考虑井口装置及采油树设备的性能等级、可靠性和使用寿命等因素,确保设备在额定工作压力、额定工作温度以及高含硫化氢的介质下高效稳定地工作。相较于常规PR1级,API 6A规范对井口装置及采油树设备关键部件的PR2级性能测试有严格的试验程序和验收要求。文章介绍井口装置及采油树设备关键部件之一芯轴式套管悬挂器和油管悬挂器的PR2性能测试过程、方法及注意事项,供同行参考交流。展开更多
The demagnetization curves of Pr2Fel4B nanocrystalline magnets are calculated using micromagnetic finiteelement method. Samples with three different distributions of grain size are simulated. We find that the remanenc...The demagnetization curves of Pr2Fel4B nanocrystalline magnets are calculated using micromagnetic finiteelement method. Samples with three different distributions of grain size are simulated. We find that the remanence enhancement does not depend on grain size distribution but on the mean diameter of grains, and the influence of grain size distribution on coercivity is affected by the strength of intergrain exchange coupling.展开更多
文摘The demagnetization curves of Pr2Fel4B nanocrystalline magnets are calculated using micromagnetic finiteelement method. Samples with three different distributions of grain size are simulated. We find that the remanence enhancement does not depend on grain size distribution but on the mean diameter of grains, and the influence of grain size distribution on coercivity is affected by the strength of intergrain exchange coupling.