隔声体性能评价的方法研究

On Performance Evaluation of a Sound Isolator.

提出了在实验室内评价声波测井仪器的隔声体性能的评价方法。在实验室评价隔声体的性能时 ,应在隔声体的两端各连接一定长度的补偿管用于模拟隔声体上下两端的部件和消除边缘效应 ;应采用激震源和接收信号的三轴加速度计均放置在隔声体外侧两端的测量方案 ,用以消除不同加速度计的物理性能不一致对测量结果的影响。三轴加速度计作为接收探头可以评价隔声体的相互正交的 3个振动方向上的隔声量和时延量。

In general, an acoustic well logging tool is mainly composed of transmitters and receivers, sound isolator and electronic sonde. The sound isolator used to link transmitter and receiver has two main functions, one of which is to attenuate various acoustic signals to avoid unwanted acoustic signals propagating through the logging tool, the other is to support a certain time delay, so that the signals propagating through the logging apparatus are delayed enough to the signals propagating through borehole fluid and formations. Therefore, sound insulation and time delay are two key parameters of an isolator. Although various acoustic well logging tools have been developed and used widely, to our knowledge, so far, there are no publications on evaluating the performance of sound isolator. In this paper, we present a method to evaluate the performance of the sound isolator of acoustic well logging tools in laboratory. In order to simulate the other parts of acoustic well logging tool except isolator and to eliminate the boundary effect, two sections of pipes with certain length should be connected to the two ends of the isolator. Two vibration sources and two tri axial accelerometers outside the isolator should be used to eliminate the unwanted influence resulted from the disagreement of performance of different tri axial accelerometers. It is possible to evaluate three components of sound insulation and time delay of an isolator by tri axial accelerometers. Measurements setup and case studies are described in this paper.