Background Underground borehole measurement emerges as a core technology for the safe production of coal mines. Its multi-parameter measurements, data accuracy, data transmission rate, and reliability directly influence the timeliness of early warning for disasters, the operating stability of instruments, the accuracy of borehole assessment, and the scientific rigor of intelligent decision-making under complex deep geological conditions.

Advances  So far, the measurement while drilling (MWD) and post-drilling borehole visualization techniques have developed into a diversified technological system. Specifically, the MWD technique has achieved a leap from wireline to wireless transmission, obviating the reliance on wireline drill rods in traditional measurement methods and enabling the collaborative development of the real-time monitoring of borehole trajectory parameters, stratigraphic information, and drilling conditions. For this technique, the gyroscope-based MWD system effectively addresses the issue of magnetic interference, significantly enhancing the timeliness and accuracy of measurements; the geosteering MWD system enables precise identification of coal-rock interfaces; and the engineering parameter MWD system, by integrating sensors for vibration, drilling pressure, and other parameters, provides comprehensive engineering parameters for the drilling process. By developing storage-type, push-rod-type, and drill-rig-propelled equipment, the visualization technique for post-drilling borehole measurement allows for fine-scale assessment of borehole trajectories and geological information.

Prospects  To address issues of borehole measurement techniques, such as low accuracy, insufficient multi-parameter fusion, and low data transmission rates, against the backdrop of intelligent coal mine construction, future research should focus on the collaborative optimization of high-precision sensors and intelligent algorithms, as well as technologies for the rapid acquisition and transmission of multiple types of data within boreholes, the intelligent optimization and control of borehole trajectories, and dynamic real-time correction of errors in post-drilling borehole measurement. These research efforts will provide core support for precise steering and safe, efficient drilling under complex underground geological conditions in coal mines, thereby driving the transition of the coal industry toward a safe, efficient, and green intelligent mining mode.