Probe Development of Borehole Resistivity Measurement in Coal Mine

In order to better serve the disaster prevention and control work, a method of measuring the borehole resistivity is proposed in the fine geological exploration and coal mining. It measures the resistivity variation curve on the borehole profile, so as to divide the coal field strata and identify the geological anomaly areas. Firstly, we have designed a device which can generate a frequency of 0-1 MHz, based on the measurement model of a symmetrical four stage device. Then the automatic range conversion module is designed, including full differential amplifier circuit and high-speed AD circuit signal acquisition unit. Finally, the device coefficient K of the probe tube is calibrated by linear regression analysis. The performance test results show that the measurement error of resistivity probe tube is 0.2%, which can meet the needs of fine detection in coal mine borehole. (paper)