Study On Simulation Model Of Transmission Line Communication System In Intelligent Drill String

Currently, the information transmission speed and efficiency of the mud pulse way has been unable to meet the development of drilling field and drilling technology. Intelligent drill-pipe can transport enough power from the ground to the underground to control the downhole instrument sensor and the dedicated hardware, at the same time can transport many types of parameters with 104～106bit/s ultra-high-speed to really realize the function of monitoring and controlling multi-parameter real-time transmission while drilling, and build information channel of the real-time and two-way close-loop while drilling between the ground and downhole. It is the key technology and development direction of the intelligent drilling. And the transmission cable is an important part of the intelligent drill-pipe, in a variety of signal transmission way of drilling, cable transmission has its unique advantages, is the future development direction of intelligent drilling signal transmission.According to the structural features of intelligent drill-pipe and the basic theory of transmission line, the main parameters affecting transmission line communication is analyzed, the general characteristics by calculating and simulating is researched, discussing its influencing factors, calculating transfer matrix of transmission lines of the single drill pipe, drill pipe joint and both multi-stage cascade based on transmission line transfer function, the corresponding transmission line impedance model is established, providing a theoretical basis for the entire communication system.The intelligent drill-pipe transmission line channel characteristics is described, analyzing the modules communications system. Combining the transmission line impedance model and the communication system model and using MATLAB/Simulink simulation software to the simulation experiment and result analysis, the BER curves are drawn, analyzing different SNR, different transmission speeds, and different transmission distances and different demodulation method is how to affect the performance of data transmission.The establishment of the impedance model and the communication model of the transmission line in the intelligent drill-pipe is completed, carrying on the corresponding simulation experiments and simulation analysis, which provides a theoretical reference for the intelligent drill-pipe design.