Research On Technology Of Adaptive RFID Communication And Its Application In Harsh Conditions

One of the important technical problem that petroleum drilling tools confronted with is how to realize high efficiency and low cost of operation and control of the downhole tool. As a non-contact automatic identification technology, RFID was provided with advantages such as waterproof, anti-magnetic, high temperature resistant, long service life, the tag information changes, leading to the good application prospect in the field of petroleum drilling tools control. However, as the harsh and changeable downhole condition in practical engineering application which results in the RF front-resonance deviation and impedance mismatch that directly affect the stability of the RFID communication system, leading to become one of the important reasons of the disability of the popularization and application in the field of the control of the downhole tool for the technology at present. In response to the RFID communication stability problem, RFID communication adaptive adjustment method under severe operation conditions was proposed in the study, which can well solve the problem related to the RFID system stability under the condition of communication and poor adaptability. The main research content was listed as follow:An adaptive impedance adjustment method based on variable capacitor array was proposed, The method provides the basis for the determination of the resonance point, the method of phase difference measurement, the value of each capacitor in the capacitor array and its combination mode, the process of adaptive impedance adjustment,which provide the basis for the detailed design of the function module. Finally, the error caused by discrete capacitor is analyzed, It is concluded that the resonance point matching error can be controlled within 2.6kHz.An adaptive control method based on the connection between frequency sweep and variable capacitor array was proposed, The method firstly introduce the frequency scanning method including the basis for the determination of the resonance point, phase difference measurement method and frequency scanning step, then give the method and the process of the combination of frequency scanning method and variable capacitance array method. which provide the basis for the detailed design of the function module. Finally, through the analysis and comparison, it is concluded that the method can reduce the matching error of the resonance point in the 0.5kHz range, and improve the precision of the adaptive impedance adjustment.Adaptive adjustment module, as well as the related soft and hardware has been designed based on the adaptive control method based on the connection between frequency sweep and variable capacitor array. In addition, it has been tested and applied in Sinopec development project related to reaming while drilling(RWD) electrical control system.The research achievements not only succeeded in solving the affection that results from severe operation conditions in the field of petroleum drilling on RFID communication, but also equally applied to the RFID technology under severe operation conditions in other fields.