雪峰造山带东侧复杂地层岩心钻探关键技术

Key core drilling technologies for complex strata on the eastern margin of the Xuefeng orogenic belt

摘要:

雪峰造山带东侧桃江地区受多期构造叠加影响，地层破碎、软硬岩层互层、裂隙发育，岩心钻探面临孔壁失稳、冲洗液漏失严重、取心困难等突出难题，亟需构建一套适用于该区域的系统化钻探技术体系。以该区ZK0001、ZK1901、ZK2402三个典型钻孔为工程实例，系统分析钻遇地层岩性特征与复杂构造条件，针对各类孔内复杂工况，集成应用钻头序列化优选、三级钻孔结构动态优化、破碎地层取心工具改进与钻进参数调控等成套工艺，建立依据漏失速率分级的“随钻防漏-桥接堵漏-复合凝胶堵漏”堵漏技术体系。工程实践表明：优选孕镶金刚石钻头后，含砾砂岩段单只钻头有效进尺提升至80~150 m；侧喷式钻头搭配轻压慢转钻进规程，破碎含锰矿层岩心采取率稳定达到95%以上，局部可达100%；该堵漏体系可高效处置漏失速度3~11 m3/h各级漏失；ZK2402承压涌水层段采用加重冲洗液控压钻进，施工完成后套管永久保留，实现勘查钻孔“一孔多用”，转化为乡村供水设施。研究形成了一套适配雪峰造山带东侧复杂地层的高效、安全岩心钻探关键技术体系，可为同类陆内造山复杂构造区矿产勘查钻探工程提供技术参考。

Abstract:

The Taojiang area on the eastern side of the Xuefeng orogenic belt has been subjected to multi-stage tectonic superposition， resulting in fractured strata， interbedded soft and hard rocks， and well-developed fractures. Core drilling in this area faces prominent challenges， including borehole wall instability， severe drilling fluid loss， and difficult core recovery， necessitating the establishment of a systematic drilling technology system tailored to this region. Taking three typical boreholes （ZK0001， ZK1901， and ZK2402） in the study area as engineering cases， the lithological characteristics of the drilled formations and complex structural conditions were systematically analyzed. To address various downhole complexities， an integrated suite of techniques was applied， including serialized bit optimization， dynamic optimization of the three-stage borehole structure， improvement of coring tools for fractured formations， and adjustment of drilling parameters. Furthermore， a graded lost circulation control system based on leakage rate classification was established， featuring "loss prevention while drilling， bridging plugging， and composite gel plugging." Engineering practice demonstrates that： After optimizing impregnated diamond bits， the effective footage per bit in gravel-bearing sandstone intervals increased to 80~150 m； using side-jet bits combined with low weight-on-bit and low rotary speed drilling parameters， the core recovery rate in fractured manganese-bearing ore layers consistently exceeded 95% and locally reached 100%； the plugging system efficiently handled various levels of lost circulation with leakage rates ranging from 3 to 11 m3/h. In borehole ZK2402， weighted drilling fluid was employed for managed-pressure drilling in the confined water-influx zone， and the casing was permanently retained after completion， thereby achieving "one hole for multiple purposes" and transforming the exploration borehole into a rural water supply facility. This study establishes a key technology system for efficient and safe core drilling adaptable to the complex strata on the eastern side of the Xuefeng orogenic belt， providing a technical reference for mineral exploration drilling projects in similar complex intracontinental orogenic structural zones.