井下通信线圈的谐振频率自适应检测技术研究

Research on adaptive detection technology of resonance frequency of downhole communication coil

常规旋转导向的井下无线短传是磁耦合式定频传输的,存在通信线圈的谐振频率随环境变化的现象,容易导致接收信号强度随钻进过程浮动,严重时可能收不到信号,甚至造成乱码。本文提出了基于自动窗口算法自适应检测井下通信线圈谐振频率的技术,先从井下通信线圈谐振频率自检原理入手;然后对比4种自适应选频算法,确定自动窗口算法是更合理的自适应选频算法;最后采用自适应选频和扫频2种方法,对定制的两批井下线圈进行谐振频率检测,论证了自动窗口选频技术的可靠性。该技术能够自动适应井下环境,为井下无线短传提供可靠的谐振频率参数。井下旋转变压器的电能传输效率与谐振频率密切相关,该技术也可推广至井下旋转变压器的变形设计,优化钻进过程的电能传输效率。

Conventional rotary steerable downhole wireless short transmission is magnetically coupled fixed frequency transmission,The resonant frequency of the communication coil changes with the environment,which easily leading the received signal strength floating with the drilling process,and may not be received in severe cases,and even cause garbled code.In this paper,an adaptive detection technology of downhole communication coil resonance frequency based on automatic window algorithm is proposed.It starts with the introduction of the self‑detection principle of downhole communication coil resonance frequency.Then compared with four kinds of adaptive frequency selection algorithms,the automatic window algorithm is determined to be the more reasonable adaptive frequency selection algorithm.Finally,adaptive frequency selection and frequency‑sweep method are used to detect the resonant frequency of two batches of customized downhole coils,in order to demonstrate the reliability of automatic window frequency selection technology.This technology can automatically adapt to the downhole environment and provide reliable resonant frequency parameters for downhole wireless short transmission.As the power transmission efficiency of downhole rotary transformer is closely related to the resonant frequency,this technology can also be extended to the deformation design of downhole rotary transformer to optimize the power transmission efficiency during drilling.