电磁波随钻测量双向信号传输系统

Electromagnetic wave bi-directional signal transmission of MWD

介绍了自制电磁波双向信号传输装置的基本原理、单元结构关系、相关工作参数以及试验情况。试验结果表明,随钻测量双向信号传输系统在硬岩中传输距离远,可实时传输井下工况信息,也可从地面向井下传输指令,与智能化钻具配合,还可从地面遥控井下钻具。不同波形对电磁波双向信号传输有较大影响:正弦波有较强的抗干扰能力;方波易受地层干扰信号的影响,特别在接收信号微弱时,方波传输信号误码率较高。另外,下传信号比上传信号衰减大。

The system of two-way telemetry for drilling can transmit drilling information from bottomhole to surface in real time,and send the order from surface to bottomhole at same time.Connecting with so called intelligent drilling tool like steering drilling device,the telemetry can monitor downhole drilling situation and also realize the remote control of downhole drilling tool at will.The electromagnetic type of two-way telemetry has developed in recent years owing to its advantages of being suitable to use for air/gas drilling or foam drilling.This paper introduced the history and development situation,the principle,structure and working parameters of self-made electromagnetic two-way telemetry.Experiments indicate that waveform has an effect on two-way electromagnetic transmission.Sine wave is better than square wave in resisting disturbance.There is higher error rate for square wave especially when received signals are very weak.In addition,the attenuation of downgoing signals is large compared with that of upgoing signals.