Research and application of key technologies for small-diameter drilling in metallic mineral exploration

Abstract:

To meet the challenges of small-diameter drilling for metallic mineral exploration in deep and complex formations， this study addresses four critical issues： low penetration rates in hard rock， difficulty in borehole trajectory control， poor borehole stability in broken or lost-circulation strata， and stringent environmental constraints. Four key technologies were developed and implemented：（1） For hard， low-abrasivity formations， bit design （composite matrix， diamond specification， hydraulic configuration） and drilling parameters （high weight-on-bit， moderate rotary speed） were optimized， raising the rate of penetration by more than 100%. （2） In deviation-prone formations， an anti-deviation bottom-hole assembly coupled with a ?32mm mud-pulse MWD system was deployed， enabling a “proactive deviation prevention + dynamic correction” strategy that limits borehole deviation to ≤1.5°/100 m. （3） Formation-adapted low-solid/non-solid drilling fluid systems with adaptive control， combined with drilling-with-casing and bridging lost-circulation materials， effectively mitigate collapse， diameter reduction and mud losses. （4） Green exploration principles were integrated through low-disturbance rigs， environmentally benign drilling fluids and closed-loop cuttings management， markedly reducing environmental impact. Field trials in the Huoqiu iron deposit demonstrate significant improvements in drilling efficiency， cost reduction， and accident-rate decline， providing a robust technical foundation for efficient， accurate and environmentally sustainable deep mineral exploration.