随钻测量电磁信道分析的等效传输线法

An Effective Transmission Line Approximation for EM Channel Analysis of the Measurements while Drilling

等效传输线法用于随钻测量电磁传输信道的分析，在当前仍然是一种比较有成效的方法。本文对现有近似法中所采用的等效传输线模型作了一些改进，使之在物理图象上更为确切，并能够对井下激励装置有关参数的影响进行估计。当以实际钻具和地层的参数代入所得计算公式，能够给出与实测数据符合相当好的理论结果，说明本文的分析方法可用于随钻电磁信道传输能力的预测。

In this paper an improved effective model is presented to correct the currently applied effective transmission line method for EM channel analyses of the MWD. In our approximation the physical pattern of the problem is more clear and the effects of the structural parameters of down-hole exciting device can be evaluated. The obtained formula for surface receiving signal voltage gives the theoretical results fairly good correspondence with measurements. It is shown that the improved approximation can be effectively used to analyze and predict the EM channel characteristics of the EWD.