Research On Short-range Wireless Transmission Characteristics In Metal Pipes

With the well development of oil and gas detecting technology, the environment of the down-hole is becoming harsher and harsher. Requirements of down-hole measurement and control technology is increasingly demanding. At present, the sensors used for measure data and for MWD system was separated by motor. Between them, a relatively short blind zone communication is exists which is difficult to connect directly by cable. Wireless transmission is the best choice for information transmission. Therefore, the study of short-range wireless transmission in metal pipe is important for eliminating the blind zone of down-hole cable transmission and ensuring the information flow of the near-bit measurement technology.Aiming at requirements of the near-bit wireless data transmission, this paper examined the wireless transmission mode based on electromagnetic wave. The internal circular space inside drill pipe was used as the transmission channel. The circular waveguide was made as a starting point in this paper. With the aid of Maxwell's equations and specific boundary conditions, the transmission channel was virtual as a space field. The characteristic how main parameters of the field changed with time and space was solved, thus the theoretical analysis of transfer characteristic was achieved. Meanwhile, the transmission frequency, pipe radius of cross section, roughness, packing mediums, etc could influence attenuation characteristic of electromagnetic wave in the metal pipe was analyzed by means of numerical analysis as the core. CST software was used to simulate the field distribution of different electromagnetic wave mode in the pipeline, and the transmission loss was analyzed. Finally, the rationality of the theoretical analysis was verified by experimental test, and the communication distance is tested by the wireless link quality evaluation index.The research on the short-range wireless transmission in metal pipe had been completed in this paper. The attenuation characteristic was analyzed under different condition of pipe parameters, filling medium, transmission frequency by theoretical analysis and experimental test. At the same time, the feasibility of applying the wireless transmission based on electromagnetic waves in the down-hole environment was discussed. The research on the information communication mode of the near-bit measurement technology has a certain reference value.