Research And Implement Of Echo Detection Algorithm For Ultrasonic Logging Instrument

Logging as the important technique of exploration and development of gas fields, ithas been80years of history. Due to complex geological conditions, the problems need tobe solved are various. According to the geological and geophysical conditions, Thecomprehensive logging method must be chosen reasonably. Among them, the ultrasoniclogging technology through detecting the information of echo time and echo amplitude, toreflect the underground structure and characteristics of the oil well wall.This paper put forward the new application of the ultrasonic logging technology withdrilling logging, besides it has been used in the imaging logging. The traditional way ofultrasonic logging is to use the analog circuit to get the information of the echo time andecho amplitude. But in the test, the threshold selection problems of the analog circuit ledthe false-alarm probability and leak probability to be higher. Therefore, it is needed toimprove the system reliability. This paper put forward a new method to detect the echo.First, it makes the analog signal to the digital signal. Then taking the DSP+FPGA jointwork mode to detect the echo information through digital signal processing technology.First, this paper has token an in-depth study in the detection algorithm of theultrasonic echo. It put forward the algorithms in the echo detection with the adaption ofA/D start time, automatic gain control, Superposition average. Sliding matched filter, anddouble threshold detection. And also we put forward the new application of ultrasoundlogging technology in drilling well logging.At the same time we have given the measures for the problems of the realization ofdrilling well logging tool, such as temperature, power consumption and the reliability ofthe algorithm. And we completed the hardware and software design of the system. At lastwe verify the effectiveness and the reliability of the algorithms and the drilling welllogging tool.