Application of a top-drive core drilling rig in the construction of a 3500 m extra-deep borehole at the Xiaoqinling gold field

Abstract:

To investigate the deep metallogenic regularities of the Xiaoqinling gold field， a 3500 m scientific deep borehole was deployed in the geologically complex Xiaohe Fault Zone. The drilling operation encountered severe challenges， including borehole constriction in fault gouge， collapse in fractured zones， and stuck pipe due to high ground stress， leading to frequent downhole incidents where conventional drilling techniques proved inadequate. This paper presents the successful application of the XD-40DB AC variable frequency top-drive core drilling rig. By leveraging its core technological advantages—such as intelligent integrated control， an 18m long-stroke feed system， and precise power regulation—in conjunction with an optimized five-section borehole structure， multiple targeted drilling fluid systems， and meticulous parameter control， a comprehensive construction technology applicable to extra-deep boreholes in complex formations was developed. This technological system effectively overcame challenges like borehole instability and stuck pipe， achieving a final depth of 3491.90 m and an average core recovery rate of 97.18%， thereby successfully fulfilling the geological objectives. The findings not only provide crucial geological data for studying the ore-controlling mechanism of the Xiaohe Fault but also validate the exceptional performance and pivotal supporting role of top-drive core drilling rigs in deep exploration within complex formations， offering a significant technical demonstration and practical experience for similar extra-deep drilling projects in China.