短距离钻柱声波传输特性试验研究

Experimental Study on Short-range Acoustic Transmission Characteristics in Drill String

为研究钻井中短距离钻柱的声波传输特性,在1.28 m长的钻柱上建立了一套短距离声波传输试验系统,对声波信号在短距离钻柱中的传输特性进行了试验。试验以方波为驱动信号,采用径向和轴向钻柱激励,激励频率从2 Hz升高至50 Hz,传感器安置于接收端各个不同位置。试验研究声波信号对驱动电压、激励方向、激振频率以及传感器测量方向等参数的敏感性。试验结果表明,声波信号在传输过程中有衰减并含有回波和大量噪声干扰,在井下工具能耗允许范围内可采用大电压供电、径向激励钻柱和传感器径向接收信息的方式。

To study the short-range acoustic transmission characteristics in the drill string, a set of shortrange acoustic transmission test system is established on a 1.28 m drill string and the acoustic transmission characteristics are tested. In the test, square wave is used for drive signal. The radial and axial drill string excitations are adopted and the excitation frequency is increased from 2 Hz to 50 Hz. The sensors are placed in the receiving end at different locations. Based on the system, the acoustic signal sensitivities to the drive voltage, excitation direction, excitation frequency and the sensor directions are studied. Experimental results show that the acoustic signal has at- tenuated during transmission and contains echoes and many noises. Large supply voltage, axial drill string excitation and radial signal receiving sensor should be adopted within the energy consumption range of downhole tool.