石油勘探用薄圆环压电换能器的瞬态特性分析

SOURCE FUNCTION DERIVATION AND PROPERTY ANALYSIS OF CERAMIC RING TRANSDUCER FOR PETROLEUM EXPLORATION

分析了石油勘探中采用的薄圆环压电换能器的瞬态响应，研究了它的等效电路并确定了电压激励信号与换能器瞬态振动之间的转换函数。利用留数定理，推导出了在两种类型电压信号激励下，薄圆环压电换能器声源函数的时域及频域的解析式，同时真实地表示了薄圆环压电换能器的实际声源函数。选择合适的压电材料和周围的耦合液体，可以改善发射声波信号的质量．在一定发射功率条件下，保持换能器的几何尺寸不变，降低换能器的共振频率，从而能增加声波测井仪的探测深度和随钻测量（ＭＷＤ）声纳导向系统的测量距离。

Because the directivity of a thin ring transducer is better than that of the a thin cylinder transducer,some oil companies have begun to use the thin ring transducer as the element of array source in the MWD sonar guidance system and acoustic logging tool.This paper analyses the transient response of the ring transducer for petroleum exploration,develops the equivalent circuit and determines the transfer function between electrical driving signal and the transient motion of the transducer.By using the residue principle,the transient functions of the temporal and frequency domains for the transducer are determined analytically shy for any electrical driving signal.The derived source function represents the real source function of ceramic ring transducer.By analyzing the property of the transducer,this paper indicates that choosing both suitable piezoelectric material and coupling fluid can improve the quality of the transmitted acoustic signal,and also reduce the resonance frequency of the transducer to a certain extent When its geometrical size can not bi changed, therefore, the investigation depth of acoustic logging tools and the measuring distance of MWD sonar guidance system can be increased