钻柱声波传输信道频谱特性分析

Analysis of the Spectrum Characteristics of Acoustic Wave Transmission Channel for Drill String

井下钻柱对于声波传输是一个非常复杂的介质空间,对声波在钻柱信道中的频谱特性进行分析可知,钻柱信道的一个最明显特征就是通带和阻带相间,具有多波段传递函数特征。钻柱结构的几何尺寸决定了信道的频谱特性,不同尺寸结构组成的钻柱,通带将变窄,一个频带周期的中心频率附近出现完全阻带,随着结构复杂程度的增加,声传输频谱特性变差。钻柱结构的安装排列方式对信道频谱特性存在影响,根据不同尺寸结构选择合适的安装形式,将在一定程度上改善频谱特性,在1 kHz以内的频率范围内,频谱结构相对稳定。

Downhole drill string is a very complex medium space for sound-wave transmission. An analysis of the spectrum characteristics of sound and wave in the drill string channel was conducted. The analysis shows that a re- markable feature of drill string channel is the alternation of pass band and stop band. It has a multiband transmission function feature. The geometric dimensions of the drill string structure determine the spectrum characteristics of the channel. As for the drill strings composed of different dimensions, the pass band will become narrow. The complete stop band will occur near the central frequency of a band cycle. With the raise of structural complexity, the acoustic transmission spectrum performance will become poor. The installment and arrangement modes of drill string structure have effect on the channel spectrum characteristics. Selection of the proper installment mode according to different dimensions can improve the spectrum characteristic to some extent. Within the scope of 1 kHz frequency, the spectrum structure is relatively stable.