**4. Management of Drilling Process and Drilling Effect**

The efficient extraction of gas is closely related to the quality of extraction boreholes. In addition to the reasonable design of boreholes, precision borehole construction is essential. At present, there is a serious disconnection between borehole construction and borehole design, and drilling site constructors have the tendency of blindly pursue drilling footage due to the lack of supervision of drilling site construction, resulting in a discrepancy between drilling construction parameters and design, inadequate borehole construction and unclear description of the site and other major hidden dangers that threaten coal mine production safety. In order to improve the quality of drilling construction, it is necessary to effectively manage the drilling process and drilling effect.

(1) Management of drilling process

In order to ensure the precise construction of drilling, it is necessary to timely acquire the drilling hole angle, hole position, drilling distance, and so on, to avoid safety accidents caused by deviation of drilling construction. As an effective method to manage drilling process, drilling video-surveillance systems are widely used in coal mines. The working principle of the system is to collect video information during the drilling process through an underground high-definition camera, and transmit the video signal to the ground server by optical cable transmission technology to realize the real-time monitoring of the drilling site. The network topology and monitoring effect are shown in Figure 4.

**Figure 4.** Network topology diagram of drilling video surveillance system and monitoring effect.

#### (2) Management of drilling effect

In order to reduce the influence of gas-extraction borehole construction deviation on gas extraction, the drilling trajectory measurement device is used to measure the construction trajectory of gas-extraction borehole. In the process of drilling construction, the probe tube is installed in the non-magnetic drill pipe behind the drill bit, and the probe tube is drilled forward with the drilling rig. The basic data such as drilling depth, dip angle, and azimuth angle are measured and recorded by hand-held data storage instrument, and the data processing and automatic generation of drilling trajectory are carried out by professional software. The drilling trajectory measurement device and measurement results are shown in Figure 5.

**Figure 5.** Drilling trajectory measurement device and measurement results.
