钻柱结构差异对声传性能的影响

Impact of drill string structural difference on acoustic transmission characteristics

深入研究声波在钻柱信道中传播性能,对于声传输系统的研发具有重要意义。首先借助瞬态分析方法对管柱的频域特性以及声波在管柱中的传播特性进行了分析,然后利用复杂钻柱结构的声传播特性分析模型,采用传递矩阵法分析了不同钻柱结构的声传性能,最后依据钻柱动力学和波动理论对耦合钻井液因素的影响进行了研究。结果表明,钻柱的几何结构对于其频域特性有着显著影响,结构差异对于信道的频带结构和通频带分布有着较为显著的影响,钻柱中各部分的尺寸差异会使通频带变宽,声波透射幅值下降。依据钻柱中结构各部分声阻抗大小,采用合理的排序方式,可以增强通频带的稳定性。通过对通频带变化规律和钻井噪声频率范围的分析,确定出了钻柱作为声传信道的声波通信载波基本选频范围为400～1 000Hz的通带。

It is of great significance to the development of acoustic transmission system to study the acoustic transmission properties of acoustic wave in a drillstring channel. First, the transient finite element~ analysis is made for the frequency domain characteristics of a pipe string and the wave transmission properties in it. Second, acoustic transmission characteristics of acoustic wave within a complex pipe string are analyzed with the transfer matrix method. Finally, the impact of coupling drilling fluid is studied based on drill string dynamics and the wave theory. The results show that the geometric structure of a drill string has a significant effect on frequency domain characteristics. Therefore, the structural difference can impose a great impact on the frequency band and passband distribution of drillstring channel. The dimension difference of each part of a drill string will also broaden the passband and cause the decline of wave transmission amplitude. The stability of a passband can be strengthened by making reasonable arrangement according to the acoustic impedance of each structure in the drill string. The spectrum variation law of passband and the drilling noise frequency range are analyzed to determine the passband of a drillstring channel with the basic frequency selective range of 400 1000 Hz.