| The downhole operation robot which has the advantages of simple structure,convenient control,high working efficiency and can operate multiple underground oil and gas layers through a single trip,has become the development direction of multi-layered wells and horizontal wells.However,the operation requires precise positioning,identification,and real-time control of intelligent tools,making downhole data transmission extremely important.The existing drilling process data transmission and intelligent well data transmission methods can not meet the data transmission needs of robots.NFC can identify devices within a short distance and exchange data quickly and efficiently,providing new ideas for data transmission of robot operations.According to the characteristics of NFC technology and the need for real-time bidirectional wireless data transmission,this article chooses NFC technology as the data transmission technology for robots.And a set of overall scheme of multi-layer NFC wireless data transmission system was proposed,which enables the robot to accurately locate,identify,and control the many intelligent tools downhole,which is of great significance for the robot operation in the well.The main research contents are summarized as follows:(1)Taking the data transmission between the robot and the downhole smart tool as the research object,the research status of downhole data transmission technology at home and abroad was analyzed,NFC technology was used for data transmission combined with requirements of robots,compared with different data transmission methods.(2)Based on the wireless transmission theory of NFC technology,combined with NFC characteristics,a set of overall scheme of multi-layer NFC wireless data transmission system was proposed,and hardware design and implementation were carried out.The hardware experiment platform was set up to conduct experimental research,including NFC modules and tags,data transmission experiments between two NFC modules,which was used to simulate the positioning,identification and controlling of downhole smart tools by the robot operation,which verified the feasibility of the program.(3)The effect of downhole environment on the NFC wireless data transmission system is analyzed by ANSYS.The eddy current effect of the metal tube causes the coil magnetic field to be smaller than that in the air.By adding ferrite shield,the metal tube influence can be effectively isolated.The suggestions of how to select ferrite shield parameter are also given.(4)The experimental study was carried out.The inductance value of the coil which was measured by impedance analyzer compared with the simulation value,to obtain the effect of the metal tube and the shielding layer on the magnetic field of the coil.The experimental platform was set up and related experiments were carried out,including the experiment of induced voltage,the sensing distance and the speed of induction in the pipeline with different diameters of transmitting coil and fixed diameter label,which verified the feasibility and reliability of NFC wireless data transmission system. |
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