By analyzing and summarizing some difficulties during the construction process of a large scale HDD project crossing typical high slat formation in Iraq, such as high reaming torque, instable mud performance, pullback difficulty and so on, some conclusions are drew. Firstly, the type and combination of drilling rigs and tools shall be considered carefully in this type of horizontal directional drilling engineering construction.The drilling bit with size of 1058 inches or above shall be used for pilot hole construction,and the plate reamer shall be used for reaming construction.Secondly,some buoy-ancy control and emergency measures shall be taken during the pullback process of large diameter thin-walled pipeline crossing construction. Finally, reasonably choosing mud formula which is suitable for high salt formation so that the mud performance in high salt formation can be guaranteed.%通过总结伊拉克地区典型高含盐地层大型定向钻穿越工程的施工过程,分析扩孔扭矩大、泥浆性能失稳及回拖困难等施工难点,最终得出结论:在该类型的水平定向钻工程施工中应做好钻机、钻具的选型和组合,建议在条件允许情况下采用1058 in或更大尺寸钻头进行导向孔施工,采用板式扩孔器进行扩孔;在大口径薄壁管道穿越施工回拖过程中,应根据实际情况采取必要的降浮措施和应急措施;合理选择适用于高含盐地层的泥浆配方,保证高含盐地层条件下的泥浆性能.
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