Key technologies of surface efficient life support hole forming for mine rescue

The surface life support hole, as the support channel for the trapped people underground, is one of the important ground emergency rescue schemes for the situation with some people trapped underground due to mine accidents. Under the complex conditions of the rescue area, including easy collapse, easy leakage, large water inflow and inclined formation, the single hole forming process has the problems such as poor ground adaptability matching, low comprehensive drilling efficiency and difficult roadway penetration, which cannot meet the requirements of rescue. In order to form an efficient drilling technology system for life support holes and improve the response speed of emergency rescue, it is determined from the point of solving the scientific and key technical problems such as low drilling efficiency and difficult roadway penetration that rapid and safe drilling and accurate roadway penetration are the two core tasks of efficient drilling: Focusing on rapid and safe drilling, researches were conducted on the drilling technologies such as high-pressure jet, air DTH hammer with casing, composite drilling, air DTH hammer, and double bit self-balance for the thick overburden and complicated bedrock, thus forming a combination of rapid and safe drilling technology for the safe and efficient drilling in deep overburden, the speed and efficiency improvement of compound one-trip drilling in the overburden, and the speed and efficiency improvement of one-trip drilling in the bedrock with air DTH hammer. As for the accurate roadway penetration, the key technical methods of compound drilling trajectory monitoring and control, as well as air drilling trajectory monitoring, were expounded for the borehole trajectory control mechanism of different drilling processes. Meanwhile, an ultra-short distance spiral deviation correction technology was proposed based on the failure of roadway penetration in large offset wells at the emergency rescue site. The results were applied to the engineering test of life support holes in Meihuajing Mine, Ningxia. Specifically, the borehole, with a depth of 670.50 m and a diameter of 215.9 mm, was drilled at an average speed of 14.32 m/h in 46.83 h, of which the horizontal displacement at the bottom was 0.27 m, and 55 h was taken in total from spud-in to casing running. Hence, it is proved that the technology system could ensure the efficient completion of life support holes within the 72-h golden window, providing technical support for the construction of surface borehole for emergency rescue.