硬脆性破碎地层低固相成膜冲洗液研究与应用

Research and Application of Low-Solid Film-Forming Flushing Fluid for Hard-Brittle Fractured Formations

摘要:

针对南丹县某矿区多钻孔钻遇破碎地层时频繁出现的坍塌掉块与阻卡等技术难题，本文在系统分析矿区地质特征的基础上，提出了孔壁稳定冲洗液技术对策，并开展了现场应用。受丹池断裂带影响，硅质泥岩岩体节理裂隙极为发育，表现为硬脆性破碎特征，在机械扰动作用下，层间结构极易发生失稳破坏，形成角砾状、碎块状剥落物，进而引发大规模掉块及坍塌卡钻等复杂情况。为此，本文研究探索了“无固相植物胶体系冲洗液、低粘土相硅酸盐防塌冲洗液、低固相成膜冲洗液体系”等多种冲洗液配方，最终研发出适用于该矿区破碎地层的低固相成膜PAC-LV+PVA1788冲洗液体系。该体系的创新性在于：可发挥低固相体系中粘土颗粒的骨架作用，在GSP分散活化下，利用PAC-LV的颗粒桥接与PVA1788的疏水锚定协同成膜，于硅质泥岩孔壁快速生成致密韧性内外泥饼，兼具物理封堵与化学固壁双重功能，解决了硬脆性破碎地层微裂隙长时效封堵的工程难题。现场应用效果良好，为广西“锡、锑、铟”等关键金属找矿突破行动提供了有力支撑。现场应用效果良好，为广西“锡、锑、铟”等关键金属找矿突破行动提供了有力支撑。

Abstract:

To address the frequent technical challenges of borehole collapse, block falling, and pipe sticking encountered in multiple drill holes penetrating fractured formations in a mining area of Nandan County, this study proposes technical countermeasures for wellbore stabilization using flushing fluid based on a systematic analysis of the geological characteristics of the mining area, and field application was carried out. Influenced by the Danchi fault zone, the siliceous mudstone rock mass exhibits extremely developed joints and fissures, displaying hard-brittle fractured characteristics. Under mechanical disturbance, the interlayer structure is highly susceptible to instability failure, forming brecciated and fragmented spalled materials that further trigger large-scale block falling and collapse-induced pipe sticking. To address this, multiple flushing fluid formulations were explored, including solid-free plant gum systems, low-clay-phase silicate anti-collapse systems, and low-solid film-forming systems. Ultimately, a low-solid film-forming PAC-LV+PVA1788 flushing fluid system suitable for the fractured formations in this mining area was developed. The innovation of this system lies in utilizing the skeleton role of clay particles within the low-solid-phase system. Under GSP dispersion and activation, PAC-LV particle bridging and PVA1788 hydrophobic anchoring synergistically form a film, rapidly generating a dense and tough internal/external mud cake on the siliceous mudstone borehole wall. This system combines the dual functions of physical plugging and chemical consolidation, effectively solving the engineering challenge of long-term micro-fracture plugging in hard-brittle fractured formations. Field application has yielded favorable results, providing strong technical support for the prospecting breakthrough of critical metals such as tin, antimony, and indium in Guangxi.