井下无线射频识别信号传输特性的模拟研究

Simulation Study on the Transmission Characteristics of Downhole Wireless Radio Frequency Identification Signal

无线射频识别信号传输技术可用于遥控井下工具,具有非接触传输、功耗小、操作便利、成本低等优点,是智能化钻完井技术的新发展方向。然而,复杂的井下环境会对井下无线射频识别信号传输的可靠性产生极大的影响。该研究结合电磁波传输理论和法拉第电磁感应定律,综合考虑了不同传输介质等井下环境的影响,建立了井下无线射频识别信号传输的理论模型,并通过数值模拟验证了该理论模型的准确性。基于该模型分析了激励电压幅值、传输距离及钻井液性质对井下无线射频识别信号传输特性的影响。研究结果表明:随着钻井液电导率的增加,信号衰减程度变大;随着传输距离的增加,无线射频识别信号传输强度变弱;随着激励电压幅值的增大,无线射频识别信号传输强度变强。理论模型与仿真模型最小误差为1.67%,具有一定的参考性。该研究可为井下工具无线传输技术提供理论依据,有助于推动井下信息无线传输技术的发展。

Wireless radio frequency identification(RFID)technology can be used to remotely control downhole tools.It is the new development direction of intelligent drilling and well completion technology because of the advantages of non-contact transmission,low power consumption,convenient operation,low cost,etc.However,the complex downhole environment can have a great impact on the reliability of downhole wireless RFID signal transmission.In this paper,the transmission model for the downhole wireless RFID signal is established by combining the Maxwell’s equations and Faraday’s law of electromagnetic induction.Different transmission media and other downhole environmental impacts are comprehensively considered.And the accuracy of the theoretical model is verified by numerical simulations.Based on this model,the influences of excitation voltage amplitude,transmission distance and drilling fluid properties on downhole radio frequency signal transmission characteristics are analyzed.The research results show that:with the increasing of the drilling fluid conductivity,the signal attenuation increases;with the increasing of the transmission distance,the transmission strength of the radio frequency signal becomes weaker;with the increasing of excitation voltage amplitude,the transmission strength of radio frequency is stronger;the minimum deviation between the transmission model and the simulation model can reach 1.67%,which has certain reference value.This research can provide theoretical basis for wireless transmission technology of downhole tools and help promote the development of wireless transmission technology of downhole information.