Establishment And Simulation Of Non - Uniform Transmission Line Impedance Model For Intelligent Drill String Cable

In the promotion of new technology, such as geo-steering drilling, directional well, horizontal well, and intelligent well, petroleum industry entered automation, information and intelligent, more and more dynamic drilling parameters need to be collected and recorded. The traditional MWD wireless information transmission mode can’t satisfy a large number of drilling parameter transmission requirements, exposed the shortcomings of the low data transmission rate, delay, and only simplex communication. Under the new challenge of information communication technology in petroleum drilling, intelligent drill string not only can achieve power electrical energy transmission from ground to underground, also provides the possibility to realize high-speed wired information transmission. Cable is suitable for the various drilling signal with its unique advantages in remote distance information transmission. Cable is the future development direction of intelligent drilling signal transmission.In this paper, channel model of intelligent drill string of non-uniform transmission lines was researched based on the non-uniform transmission lines theory. The impact factor of the intelligent drill string cable transmission characteristics was analyzed by combining the intelligent drill-pipe structure with power transmission line characteristics, as the starting of the intelligent drill string cable that mixed power non-uniform transmission line and information transmission line.The electrical characteristic parameters of intelligent drill pipe and joints was analyzed, according to the road characteristics and distributed parameter model of non-uniform transmission lines. Considering the influence of temperature change on the intelligent drill-pipe impedance, the intelligent drill-pipe cable non-uniform transmission line impedance model was established through transfer function and matrix. The intelligent drill-pipe cable non-uniform transmission line impedance model was simulated through building a communication system in MATLAB/Simulink, and analyzed the influence of different transmission speed, different modulation/demodulation, different transmission distance for data transmission quality.In this paper,the establishment of the intelligent drill-pipe cables non-uniform transmission line impedance model was completed. The communication model was built and simulated, in order to analyze the communication performance under different parameters. This result provides a reference for the information transmission mode of intelligent drilling.