中文摘要：

声波在钻柱中的传播特性还没有得到充分的研究。为此,分析了声波在管柱中的传播机理,建立了声透层单元模型周期分布的理想钻柱模型,依托该模型进行了声传播特性研究。研究结果表明,结构尺寸不一致对钻柱频带的宽度和分布有显著影响,对于周期性钻柱结构,钻杆、接头的长度和截面积决定了钻柱的频带结构,并且这种频带结构的变化分布呈周期性和对称性。在1个频带周期内随着频率的增加,通带先变窄再变宽,阻带则先变宽再变窄。随着钻杆根数和接头数目的增加,通带结构发生变化,通带内出现小透射峰,且小谱峰数增加。钻杆长度增加使通带变窄,接头截面面积减小使通带变宽。

英文摘要：

Sound waves are used to transmit downhole information through drillstring,which can satisfy the requirement of high speed and large amounts of data in modern drilling.It is a very promising method to transmit downhole information.However,the transmission characteristics of sound waves in drillstring have not yet been studied fully.Therefore,the transmission mechanism and property of sound waves in the string were first analyzed and the ideal drillstring model of periodical distribution of sound transparent layer element model was established.The study of sound transmission property was conducted on the basis of the model.The research findings show that inconsistency of structural dimensions has a remarkable effect on the width and distribution of the frequency band of drillstring.As for the periodical drillstring structure,the length and sectional area of drillpipe and tool joint determine the frequency band structure of drillstring.Moreover,the variation distribution of the frequency band structure is periodic and symmetric.Within one cycle of frequency band,with the increase of frequency,the passband first becomes narrow and then becomes wide,and the stopband first becomes wide and then becomes narrow.With the increase of the number of drillpipes and joints,the passband structure changes and the small transmission peaks occurs within the passband.The number of small spectral peaks increases.The increase of the drillpipe length narrows the passband and the decrease of the joint sectional area widens the passband.