海上岩心钻探防喷器辅助绳索取心技术实践与展望

Practice and prospect of blowout preventer-assisted wire-line coring technology for offshore core drilling

摘要:

小口径岩心钻探在深部矿产资源勘探、海洋地质调查等领域具有不可替代的作用，但复杂海洋环境与多类型地层条件下的井壁稳定控制、有害气体防控及全取心质量保障一直是行业技术瓶颈。针对CSDP-2井（中国东部海区科学钻探井）未固结软塑性地层取心保真难、坚硬地层岩心易磨细、破碎煤系地层取心率低、深部硫化氢异常溢出等工程难题，本文系统开展了防喷器辅助绳索取心技术改进研究。通过优化提钻速度控制策略、构建钻井液回灌压力平衡系统，解决了易缩径地层起下钻、绳索取心负压抽吸导致的井壁坍塌问题；依托防喷器压井管汇构建反循环钻井液体系，实现了井壁稳定维护、有害气体封堵、固相沉淀防控的多重目标；结合“探海1号”平台适配性改造，形成了浅海复杂环境全取心钻探技术体系。改进技术使CSDP-2井2843.18 m全井段平均岩心采取率达97.68%，创下全球陆架科学钻井全取心最高纪录；硫化氢溢出浓度控制在0.5×10^-6以下，实现安全零事故施工；工程成本远低于常规海洋油气钻探，填补了国内大陆架低成本高效钻探技术空白。结合行业发展趋势，从装备集成化、智能化控制、多场景适配等方面展望了技术应用前景，为小口径深孔复杂地层及海洋钻探提供了新的技术方案。

Abstract:

Small-diameter core drilling plays an irreplaceable role in deep mineral resource exploration and marine geological surveys， however， wellbore stability control， harmful gas prevention， and full core quality assurance under complex marine environments and diverse strata conditions have long been technical bottlenecks in the industry. To address the engineering challenges such as difficult core preservation in unconsolidated soft plastic strata， easy core abrasion in hard strata， low core recovery in fractured coal-bearing strata， and deep hydrogen sulfide abnormal overflow in the CSDP-2 well （China Eastern Sea Area Scientific Drilling Well）， this paper systematically conducted research on improvements of the blowout preventer-assisted wire-line coring technology. By optimizing the drilling speed control strategy and establishing a pressure balance system for drilling fluid reinjection， the issues of wellbore collapse caused by tripping operations in shrinkage-prone strata and negative pressure suction during wire-line coring were resolved. Relying on the blowout preventer kill mainfold， a reverse circulation drilling fluid system was constructed， achieving multiple objectives including wellbore stability maintenance， harmful gas containment， and solid phase precipitation prevention. Combined with the adaptability modification of the "Tanhai 1" platform， a full coring technology system for complex shallow sea environments was formed. The improved technology achieved a 97.68% average core recovery rate across the entire 2843.18 m well section of the CSDP-2 well， setting a global record for full core recovery in continental shelf scientific drilling. The hydrogen sulfide overflow concentration was controlled below 0.5×10^-6， ensuring zero-accident safe construction. The engineering cost was significantly lower than conventional offshore oil and gas drilling， filling the gap in low-cost， high-efficiency drilling technology for domestic continental shelves. Combined with the industry development trend， the technology application prospects are discussed from the aspects of equipment integration， intelligent control， multi-scenario adaptation， etc. It provides a new technology scheme for the small-diameter deep hole drilling in complex strata and the ocean.