Research On Matching Transmission Of High Frequency Signals Between Intelligent Drill Pipe And Electromagnetic Coupling Connector

The electric telemetry drill string composed of the intelligent drill rod cascade has the characteristics of high data transmission rate and good real-time transmission.It is a research hotspot in the field of drilling measurement in China at present.In this paper,the wiring rod body of the intelligent drill pipe is regarded as a transmission line with distribution parameters.Based on the transmission line theory and electromagnetic induction principle,the circuit analysis of the wiring rod body and electromagnetic coupling joint is carried out respectively.The impedance matching problem of the wiring rod body and the electromagnetic coupling coil is studied under the high frequency state,and the matching principle of impedance matching is used.The intelligent drill rod consisting of the wire rod body and the electromagnetic coupling joint is designed for the impedance matching compensation.By using the circuit analysis and mathematical analysis,the parameters of the compensation element and the electromagnetic parameters of the intelligent drill rod are determined based on the minimum energy consumption state of the compensation element,and the electromagnetic coupling of the wiring rod body and the electromagnetic coupling is established by establishing the wiring rod body and electromagnetic coupling.The mathematical model of the electric telemetry drill string voltage transmission coefficient is made up of the head.The voltage transmission characteristics and frequency characteristics of the intelligent drill rod and the electric telemetering drill string are analyzed under the condition of impedance matching and mismatch.The research shows that the appropriate capacitive compensator in the terminal parallel connection of the cabling body can make the intelligent drill rod in the impedance matching state.The transmission attenuation of the signal is mainly caused by the energy consumption of the electromagnetic coupling joint and the compensation component,and the electric pressure transmission coefficient of the electromagnetic coupling joint increases with the coupling coefficient.When the frequency deviates from the design frequency,the transmission line of the wiring rod of the intelligent drill pipe is mismatched with the electromagnetic coupling joint,and the impedance between the cascaded intelligent drill rods is also in the mismatch state.At this time,the multi node intelligent drill rod is used.With the increase of the number of cascade nodes,the maximum value of the voltage transmission coefficient is stable near a certain frequency point,and there is a certain bandwidth at the center of the frequency point.If the bandwidth is wide,it can be used to transmit the frequency band signal at the frequency point.The voltage transmission coefficient of the cascaded intelligent drill pipe will be cross linked at a certain frequency point,and the voltage transmission coefficient at the crosslink is about 0.8.It shows that the voltage transmission coefficient of this point is not affected by the number of concatenation nodes.The long distance narrow band signal can be realized near the frequency point,and the transmission line storage of the wiring bar under the impedance mismatch state is stored.In the terminal signal reflection,the signal voltage is enhanced by the superposition of the incident signal of the transmission line and the vector of the reflected signal.In the case of frequency mismatch,the reflection voltage produced by the transmission line impedance mismatch is used to compensate the signal transmission attenuation of the coupling joint,and the electric telemetering drill string which is cascaded by the intelligent drill rod has a long time of the signal transmission distance.