结构参数对偶极声波换能器谐振频率的影响

Impact of structure parameters on resonant frequencies of dipole transducer

偶极横波远探测技术在我国复杂地质结的构油气勘探中具有十分广阔的应用前景。换能器的工作频率直接影响声波测井的探测深度。本文对正交偶极声波测井换能器弯曲模态的谐振频率进行了解析计算,并利用有限元方法研究了其结构参数对谐振频率的影响。计算结果表明:当压电陶瓷片的长度增加时,换能器一阶谐振频率先降低后升高,三阶谐振频率先升高再降低之后又上升;当金属基片厚度增加时,换能器一阶与三阶谐振频率均升高;当压电陶瓷片厚度增加时,换能器谐振频率的变化方向与幅度还与压电陶瓷片长度等其他参数相关,有可能升高或降低。

Remote sensing logging using dipole shear wave has broad prospects in oil and gas exploration in China. Frequency of the transducer directly affects the detecting depth. In this paper the resonant frequencies of dipole transducer are studied with both analytical and finite element method. The effects of modifying the transducer＇s structural dimensions on its resonant frequencies are discussed. Results demonstrate that, as the length of piezoelectric ceramic layers increases, the 1st-order frequency increases after decreases first, while 3rd-order frequency at first increases then decreases and finally rises again. As the metal layer gets thicker, both 1st and 3rd-order frequencies increase. Impact of thickness of the piezoelectric ceramic layers on the resonant frequencies varies with other parameters.