半合管取心在纳米比亚罗辛Z20矿区钻探中的应用研究

Application research on the split-tube in drilling of Rossing Z20 Mining Area， Namibia

摘要:

针对纳米比亚罗辛Z20矿区地层岩性非均质性强、软硬岩互层与原生层理发育、硬质岩体易发生脆性崩解、节理裂隙密集发育等一系列钻探难题，为改善岩心采取质量、提高地质编录资料可靠程度，选取矿区R181破碎地层钻孔与R239完整地层钻孔作为试验研究对象，对比常规二重管取心工艺与半合管取心工艺在岩心采取率（RCR）、岩石质量指数（RQD）、岩心破碎指数（CFI）三项关键评价指标上的表现差异，并结合现场工程应用成效开展系统性对比分析。试验结果显示：半合管取心工艺三项核心指标均显著优于常规二重管工艺，且在破碎地层工况下优势更为明显；该工艺能够有效降低岩心二次破碎与岩心流失问题，避免岩体完整性评价结果失真，完整保存地层原生结构特征。现场规模化应用验证表明，半合管钻探工艺综合施工效果优异，项目累计完成钻探进尺10527.37 m，全区平均岩心采取率达95.73%，所有完工钻孔质量均被评定为优秀。研究形成的技术结论可为罗辛Z20矿区及国内外同类复杂裂隙地层钻探取心施工提供可靠技术参考，半合管取心工艺具备广泛推广应用前景。

Abstract:

Aiming at prominent drilling challenges in the Z20 Mining Area of the Rossing Deposit， Namibia， including strong lithologic heterogeneity， interbedded soft and hard rock layers， well-developed primary bedding， brittle disintegration of hard rock masses and densely distributed joints and fractures， this study intends to improve core recovery quality and enhance the reliability of geological logging data. Two boreholes in the mining area， borehole R181 in fractured strata and borehole R239 in intact strata， are selected as research objects. A systematic comparative analysis is carried out between the conventional double-tube coring technology and the split-tube coring technology， based on three key evaluation indicators： core recovery rate （RCR）， rock quality designation （RQD） and core fragmentation index （CFI）， combining with field engineering application effects. The test results demonstrate that the split-tube coring technology achieves remarkably superior performance in all three core indicators compared with the conventional double-tube technology， especially in the fractured strata. This technology can effectively mitigate secondary core breakage and core loss， prevent distortion in rock mass integrity evaluation， and completely preserve the primary structural characteristics of strata. Large-scale field application verification proves that the split-tube drilling technology delivers excellent comprehensive construction performance. A total drilling footage of 10527.37 m was completed， with an average core recovery rate of 95.73% across the whole mining area， and all finished boreholes were rated excellent in construction quality. The technical conclusions obtained in this research can provide reliable technical references for coring construction in the Rossing Z20 Mining Area and similar fractured complex strata at home and abroad， and the split-tube coring technology has broad prospects for popularization and application.