## 1 Introduction  
In the process of working face mining in coal mines, a high concentration of gas carried by the air leakage wind flow in the mining air zone accumulates in the upper corner due to the return wind; this is the main cause of gas overlimit in the upper corner and is very likely to cause serious accidents. To solve this problem, it is necessary to carry out gas extraction in the extraction zone to reduce the gas concentration in the upper corner. With traditional gas extraction technology, high-level oblique boreholes are in the fracture zone at the early stage of mining. As the working face advances, the roof of the mining air zone gradually collapses, leading to the scrapping of the high-level oblique boreholes in the fracture zone, with a high rate of scrapped holes and a low utilization rate. This leads to a low concentration of gas in the bubbling zone of the high-level oblique boreholes and thus negative gas extraction has negative effects. In view of these limitations, it is of great significance to study directional long borehole unloading gas extraction technology and improve gas management measures by combining practical needs and technical conditions. Scholars have conducted a great deal of research on high-level oblique borehole and extraction processes. In 2024, [PERSON] et al. [1; 2; 3] were the first to analyze and evaluate the distribution characteristics of the anomalous gas accumulation area in the mining air zone by using a combination of the unit determination method and numerical simulation software. They arranged high-level oblique boreholes according to the distribution characteristics of the anomalous gas concentration area to solve the problem of gas exceeding the limit in the upper corner due to a large amount of gas gushing out of the mining air zone of the synthesis mining face. However, the control range of the flat spacing of high-level oblique boreholes and intersection drilling had less influence on the concentration of gas extraction, and the drilling construction cost was higher. [PERSON] et al. [4; 5; 6; 7; 8; 9; 10; 11; 12] explored the influence law of factors such as vertical distance, flat distance, the number of boreholes, and the negative pressure of extraction on the gas extraction effect of high-level inclined intersecting boreholes in the context of the working face. However, field tests based on the optimized drilling parameters found that the construction volume of the boreholes was larger, and the construction period was longer. Based on a FLUENT numerical simulation analysis, [PERSON] et al. [13; 14; 15] explored the influence of drilling length as well as drilling spacing and the number of holes on the gas extraction effect. They found that when the drilling length reached a certain value, it was necessary to set up more than one drilling site to improve the gas extraction effect, which in turn led to the low utilization of drilling holes in the drilling site and a high rate of waste holes. Regarding directional long borehole extraction processes, in 2022, [PERSON] [16; 17; 18] and others proposed a zoning model for gas transport channels, analyzed the gas transport law using UDEC and COMSOL software, and determined the optimal parameters for directional long boreholes. This approach effectively improved gas extraction and reduced the cost of the process. In 2024, [PERSON] [19; 20; 21] conducted a theoretical analysis and calculations to determine the design of high-level drilling. After a comparison of the field measurements, an analysis of directional long boreholes, directional smooth layer drilling, and two processes of gas extraction, and an assessment of the engineering benefits, the results showed that directional long borehole unit extraction was more effective compared to smooth layer drilling, laying the foundation for the preferred pressurized gas extraction process. [PERSON] et al.