Features of the protective cover of the ultrasonic imager with high resolution

Abstract

This work describes the features and design of the acoustically semitransparent cover of a borehole ultrasonic imager with high resolution. This scanner is designed to investigate the fine structure of the well surface by ultrasonic sounding method at a frequency of 800 kHz. The ultrasonic transducer is rotating around a central axis. However, in the design of the device fixed semitransparent protective cover is provided for prevent damage of mechanical parts. Nevertheless, during reflected signals recording from the wall of well the undesirable noise reflections appear from protective cover. These noises interfere with the algorithm of detecting the main signal. The logging tool electronics is based on a single FPGA chip, its logic cells capacity allows determining the maximum reflection amplitude and its location, as well as recording the signal time window to the SD-card (with 32GB storage space). This windows are processed at the personal computer after logging. Such approach allows analyzing waveforms and noises. After a multiple laboratory and well experiments this logging tool was allow improving the design of the acoustically semitransparent protective cover for maximum attenuation of the reflection noise. In addition, the forms of the recorded acoustic signals and the design of the protective cover are given.