FCM新型环保成膜冲洗液在西藏依拉山地区强分散易剥落地层的应用

Application of FCM new environmentally friendly film-forming drilling fluid in highly dispersive and easily sloughing strata in the Yila Mountain area of Xizang

摘要:

西藏依拉山地区地质条件复杂，存在大量强分散易剥落的水敏性地层。地层主要为蛇纹石化、水镁石化和磁铁矿化的蚀变超基性岩，其中蛇纹石含量高达63%~84.4%、水镁石含量达13.7%~36.3%，蚀变带反复出现，其厚度达上百米，钻探施工中频繁遇到孔壁坍塌、钻孔缩径、卡钻埋钻、成孔率低等问题，导致孔内事故频发，严重影响钻进效率。本文在岩石矿物成分分析的基础上，分析总结此类强分散易剥落地层对钻探施工的影响原因；通过对比分析传统PHP冲洗液、低固相防塌冲洗液和FCM环保成膜冲洗液的性能及现场使用效果，优选出适合该地层施工的环保成膜冲洗液体系，并在4个钻孔成功应用，有效提升了钻探效率，取得了良好的应用效果。同时结合工程实践，总结了针对该强分散易剥落地层的跟管扩孔、冲洗液固相控制等钻探施工技术，为此类地层施工提供参考。

Abstract:

The Yila Mountain area in Xizang has complex geological conditions with extensive water-sensitive formations characterized by strong dispersion and sloughing. The strata primarily consist of altered ultramafic rocks with serpentinization， hydrotalcitization， and magnetitization， among which the serpentine content ranges from 63% to 84.4%， while the hydrotalcite content varies between 13.7% and 36.3%. The alteration zones occur repeatedly with thicknesses reaching hundreds of meters. During drilling operations， frequent issues happen such as borehole wall collapse， borehole shrinkage， sticking and burial of drilling strings， and low borehole completion rates， leading to frequent downhole accidents and severely affecting the drilling efficiency. Based on the analysis of rock and mineral composition， this paper examines and summarizes the impact of such highly dispersible and easily sloughing strata on drilling operations. Through comparative analysis of the performance and on-site application effects of traditional PHP drilling fluid， low-solid anti-collapse drilling fluid， and the FCM environmentally friendly film-forming drilling fluid， an optimal environmentally friendly film-forming drilling fluid system suitable for such strata was selected and successfully applied in four boreholes. This effectively improved drilling efficiency and yielded favorable application results. Additionally， combined with engineering practice， drilling techniques such as casing while drilling for reaming and drilling fluid solid-phase control tailored to such highly dispersible and easily sloughing strata were summarized， providing references for similar strata construction.