Development and Field Application of Ultrasonic Scanner for Coal Mine Gas Extraction Borehole Drilling

In the production process of coal mines, it is necessary to adopt the method of drilling to extract coal bed gas and reduce the risk of gas disaster in the process of coal bed mining. The geological conditions of coal mines in China are complex, the coal industry proposes to adopt the method while drilling to measure the inner diameter of the borehole and the lithological distribution of the strata during the drilling process. Based on the basic principle of ultrasonic scanner while drilling, this paper proposes the use of a self-generating and self-receiving ultrasonic probe to emit ultrasonic waves and sample the echoes in the process of drilling. This paper develops the project's ultrasonic excitation module, ultrasonic echo acceptance module, data storage module, and upper computer communication module, and designs and processes a small-size borehole ultrasonic scanner instrument with an outer diameter of less than or equal to 89mm. The field test results show that the developed ultrasonic scanner while drilling is able to measure the ultrasonic echo data with clear envelopes, which meets the measurement demand of the borehole inner diameter in coal mine drill holes while drilling.