Application of downhole control system based on RFID technology in the reaming while drilling

RFID (radio frequency identification) downhole control system was optimally designed to deal with the complex downhole situations in the process of well drilling. First, the electromagnetic properties of RFID communication sub and downhole antenna were optimized and the optimal spacing between the antenna and the inner wall of the sub shell was experimentally determined, so that the electromagnetic interference of eddy current is reduced and the RFID downhole control system can work stably. Second, the winding length of the antenna was optimized to be 300 mm according to the data exchange time of RFID system and the in-situ flowing rate of drilling fluid, so that the tag can be read accurately while it flows with the drilling fluid at high speed inside the downhole antenna. Third, the software and hardware of RFID reading control system were optimized and self-adaption optimization module and signal processing module were introduced, so that the working frequency of the system can be regulated automatically on the basis of the downhole electromagnetic environment and the system can be kept in the optimal state with the success ratio of tag reading of 100%. Fourth, the analytical accuracy of control signals was improved by means of optimization algorithm, CRC check and so on. Finally, the whole system was successfully tested in Well Shun 89 in Huaian, Jiangsu. It is verified that the whole system is reliability and stability. The research results provide the basis for the development of RFID based downhole tools in the future.