Design of near probe high precision signal acquisition array circuit for three-dimension acoustic logging tool

Abstract

Three-dimension acoustic logging tool can work in a variety of acoustic measure modes and provide 104 channels high quality acoustic waveform signals to obtain variations of formation features in three dimensions: axial, radial and circumferential, and then complete the comprehensive description of formation features. However, the propagation paths that the acoustic signals pass through are very long in some acoustic reflection measure modes, which causes the amplitudes of acoustic signals that the receiving transducer array received are very small and the signals are difficult to be extracted for they can be easily submerged in noise, thus formation information will be lost. To solve this problem, this paper designed a three-dimension acoustic high-precision signal acquisition array circuit. The array circuit, which includes 13 same acquisition boards, locates as close as the acoustic receiving probes to digitalize acoustic analog signals from eight azimuths and reduce transmission distance of analog signals that can reduce noise interference as much as possible. It is shown by noise test experiment that the circuit has low noise and high precision acquisition, it fully meets the needs of real work of three-dimension acoustic logging tool.