基于有限元法的声波遥测换能器的仿真与设计

发布时间：2018-02-16 04:17

本文关键词： 声波遥测测井仪器有限元压电换能器　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：声波遥测技术是将换能器安装在油井下,井下换能器激发油管串产生纵向振动,将声信号作为信息的载体,油管串作为声波传输的通道,将井下传感器测得的信息传输至地面的无线传输技术。此技术相对传统获取井下信息的技术,以成本低、操作方便、可实时传输等优点得到国内外测井研究者的广泛关注。本文根据压电换能器的基本原理,利用COMSOL Multiphysics有限元软件,设计声波遥测压电换能器。首先,通过对堆叠式换能器的本征频率的理论分析和仿真分析结果进行对比,验证了用有限元软件仿真分析换能器声学性能方法的可靠性。建立声波遥测压电换能器的理论模型,通过仿真分析,得到压电换能器结构、材料的改变对其本征频率的影响规律。通过分析换能器理论模型前几阶次的共振模态,得出换能器一阶共振模态为最佳振动模态的结论。进一步建立声波遥测换能器与油管耦合的有限元模型,研究声波遥测换能器的频响特性,发现换能器的工作频率为其自身谐振频率时声学性较为显著。考察换能器压电元件的结构及压电材料的选择对换能器的声学性能的影响,确定换能器压电元件由10组堆叠的轴向极化方向相反的压电陶瓷片组成,压电元件的压电材料为PZT-4。保证换能器的工作频率不变的前提下,针对换能器的发射功率问题进行结构优化。仿真结果表明增大换能器转换头与油管串的接触面积和空心锥形变径转换头结构都可以提高换能器的声阻抗匹配度,增大换能器的发射功率。本文设计了优化的换能器的整体结构,实现可发射低频大功率声信号的声波遥测换能器,对声波遥测系统的设计提供了参考性价值。
[Abstract]:The acoustic telemetry technology is to install the transducer under the well, the downhole transducer excites the tubing string to produce longitudinal vibration, takes the acoustic signal as the carrier of information, and the tubing string as the channel of acoustic wave transmission. Wireless transmission technology that transmits the information measured by underground sensors to the ground. Compared with the traditional technology of obtaining underground information, this technology has the advantages of low cost and convenient operation. The advantages of real-time transmission have attracted wide attention of logging researchers at home and abroad. According to the basic principle of piezoelectric transducer and COMSOL Multiphysics finite element software, the acoustic telemetering piezoelectric transducer is designed in this paper. By comparing the theoretical analysis and simulation results of intrinsic frequency of stacked transducer, the reliability of acoustic performance analysis method using finite element software is verified. The theoretical model of acoustic telemetering piezoelectric transducer is established. Through simulation analysis, the influence of piezoelectric transducer structure and material change on its intrinsic frequency is obtained. The resonant modes of the first several orders of the theoretical model of the transducer are analyzed. It is concluded that the first order resonance mode of transducer is the best vibration mode. The finite element model of acoustic telemetry transducer coupled with tubing is established, and the frequency response characteristics of acoustic telemetry transducer are studied. It is found that the acoustics of the transducer is obvious when the frequency of the transducer is its own resonant frequency. The influence of the structure of the piezoelectric element and the choice of piezoelectric material on the acoustic performance of the transducer is investigated. It is determined that the transducer is composed of 10 groups of stacked piezoelectric ceramic plates with opposite axial polarization. The piezoelectric material of the transducer is PZT-4.The working frequency of the transducer is not changed. The simulation results show that increasing the contact area between the transducer and the tubing string and the structure of the hollow conical variable diameter converter can improve the acoustic impedance matching degree of the transducer. The whole structure of the optimized transducer is designed to realize the acoustic telemetry transducer which can transmit low frequency and high power acoustic signals, which provides a reference value for the design of acoustic telemetry system.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE927;TE937;P631.83

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