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信号传输是随钻测井的重要组成部分, 也是随钻测井进一步发展的瓶颈.针对这个问题, 研究了由NovatekTM提出的基于钻杆内有线传输, 钻杆间电磁耦合传输的随钻信号高速传输方法.首先, 针对钻杆间的电磁耦合结构的对称性, 采用了高效的数值模式匹配法对该耦合结构进行了电磁建模; 然后, 为了优化钻杆间耦合结构的耦合性能, 利用上述的电磁建模方法对该耦合结构进行了仿真分析, 分析了该耦合结构各个参数对耦合性能的影响, 并得出了一些有意义的结论, 该结论能够指导随钻测井信号钻杆间耦合传输的优化设计.另外, 钻杆内传输线利用矩形传输线设计, 设计出了50 Ω 特性阻抗的矩形传输线, 并计算了相关损耗.最后, 通过仿真和实验验证了优化设计的钻杆间耦合传输结构具有非常好的传输性能, 并且仿真和实验结果符合良好.Lack of efficiency in transmitting logging signals has long been one of the crucial problems for the development of logging while drilling. This study aims to address this issue by using the advanced scheme for logging while drilling signal transmission, proposed by NovatekTM. The main points of the study focus on electromagnetic coupling between two adjacent pipes and the signal transmission in coaxial cables imbedded in drilling pipes. According to the axial symmetry of the electromagnetic coupling structure, the numerical mode matching is used to establish the numerical model for it. Through simulation analysis which is based on the numerical modeling of the electromagnetic coupling structure, we analyze how various parameters of the structure influence the coupling, obtain some significant conclusions, and optimize the coupling structure. The conclusions can be used to guide optimization design of coupling structure between the drill-pipe for signal transmission in logging while drilling. In addition, the rectangular transmission line whose characteristic impedance is 50 Ω is designed for the cable imbedded in the drill pipe, and the attenuation is calculated. Finally, simulation and experiment are performed for one unit of the pipeline. The results are in agreement with each other, thereby showing the good transmission performance.
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Keywords:
- logging while drilling signal transmission /
- numerical mode matching /
- electromagnetic coupling /
- rectangular transmission line







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