水平定向钻穿越海沟施工难点及处理方法

Construction difficulties and treatment methods of crossing sea trench by horizontal directional drilling

以中缅油气管道5~#海沟穿越工程为例,总结了海沟地质条件复杂和自然环境恶劣情况下水平定向钻穿越遇到的典型问题,针对软硬交界面处理、扩孔扭矩大、泥浆漏失及海水入侵影响泥浆性能、海滩管道焊接和发送等难题,通过改善泥浆性能指标、调整扩孔工艺、采用"双钻机同步扩孔"工法、利用滚轮架预制安装管道等措施,避免了塌孔、卡钻事故,成功完成管道回拖作业,为后续的海沟穿越工程提供借鉴与指导。

This paper summarizes the typical problems encountered in crossing 5~# sea trench of China-Myanmar Oil and Gas Pipeline by horizontal directional drilling under the complex geographical conditions of sea trench and severe natural environment. Aiming at the problems of interface treatment between soft stratum and hard stratum,torque control,mud loss and effect of sea water intrusion on mud performance,pipeline welding on beach and pipeline launching,the measures of improving mud performance,adjusting reaming process, adopting method of＂ double rigs simultaneous reaming＂ and adopting roller frame to prefabricate pipeline are taken to avoid the accidents of hole collapsing and tool sticking. The pipeline pull-back operation is successfully completed. The experience can provide reference and guidance for follow-up sea trench crossing projects.