Electromagnetic measurement while drilling technology based on the carrier communication principle

To improve data transfer rate and signal telemetry depth in electromagnetic measurement while drilling (EM-MWD), and to solve the problems of short life expectancy and poor reliability of drill pipes as well as serious electromagnetic scattering, this paper presents the measurement while drilling (MWD) method based on the carrier communication principle. Based on carrier technology, the electromagnetic wave signal was coupled with the drill pipe through the coupling transformer, where the drill pipe and formation can form the guiding wave system to achieve data transfer between the ground and the bottom. The transmission line equation is developed based on the analysis of the transmission characteristics of electromagnetic waves in strata and drill pipes, and the overall structure of the system is presented. The real transmitter and receiver are produced by using LM1893 as the carrier module. In addition, the system optimization is proposed. The electromagnetic waves loaded on the drill pipe using carrier technology can transmit drilling measurement parameters from the bottom to the surface in real time, and send setting parameters and commands from the surface to the bottom simultaneously through the drill pipe-formation channel, and thus achieve the implementation of bi-directional communication between the ground and the bottom.