en.Wedoany.com Reported - Recently, China's Guoshen Huangyuchuan Coal Mine completed an advanced exploratory and drainage borehole with a depth of 2,013 meters at the construction site of the 226 Upper 08 working face underground. On-site data showed stable water pressure and normal return water, meeting the design requirements. This borehole depth set a new record for underground advanced exploratory and drainage drilling in Chinese coal mines, where kilometer-level boreholes were previously considered the limit.
The geological structure of Huangyuchuan Coal Mine is relatively complex, with developed faults and collapse columns, and it is mainly threatened by water hazards from Ordovician limestone. Through hydrogeological condition analysis, the mine has built a prevention and control technical system, transforming water hazard control from passive treatment to active defense. The 226 Upper 08 working face is partially located in a pressurized Ordovician limestone water area. Facing technical challenges such as significant stratigraphic undulation changes and difficulty in controlling borehole deviation, the exploratory and drainage team needed to complete a directional borehole exceeding 2,000 meters in depth under complex conditions. Gao Jun, captain of the exploratory and drainage team, said: "Two-thousand-meter-level directional boreholes are few and far between in the field of domestic coal mine exploratory and drainage. Facing the challenges of a relatively complex geological structure and multiple water hazard risks, we achieved it."
During the construction process, the team implemented double safety measures of pre-consolidating the casing and installing a high-pressure gate valve, running a φ159 mm water-stop casing for 5.5 meters, and using double-liquid grouting for sealing and consolidation. The pressure test for the consolidated pipe required reaching 2 MPa and maintaining stable pressure for over 30 minutes. After the borehole depth exceeded 1,700 meters, the drilling rig parameters fluctuated, and resistance inside the hole increased. The operators reduced the rotation speed and feed pressure, and after two hours of adjustment, the drilling rig returned to stable operation. Chief Engineer Li Yong provided on-site guidance multiple times and established a dynamic control mechanism of analyzing once per shift and reviewing once every 50 meters of drilling. Ren Chenfeng, Deputy Chief Engineer for Geological Survey and Water Prevention and Control, led personnel to receive inclination measurement data in real-time and conduct trajectory inversion every 50 meters.
The construction of this borehole reduced the need for frequent excavation of exploratory and drainage chambers and the relocation and avoidance associated with exploratory and drainage operations. On an annual average, it reduced the impact on excavation footage by approximately 3,200 meters, decreased drilling relocations by 6 times, and increased exploratory and drainage footage by about 4,800 meters, with an estimated annual direct economic benefit of 38.4 million yuan. Yang Zhen, Executive Deputy Mine Manager of Huangyuchuan Coal Mine, stated at the summary meeting: "2,013 meters is not just a number; it is a concentrated reflection of Huangyuchuan Coal Mine's technical strength in water prevention and control, and even more so, an unremitting pursuit of the goal of 'zero water inrush, zero water permeation'." Captain Gao Jun of the exploratory and drainage team stated that the next goal is to advance towards deeper, more accurate, and safer drilling.
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