荔湾3-1气田输气管道排水干燥工艺设计与应用

Design and application of dewatering and drying techniques for gas pipeline in LW3-1 gas field

根据荔湾3-1气田浅水段登陆管线的特点对海底管线常用的干燥方法进行了研究,选择干空气干燥与三甘醇干燥相结合的排水干燥工艺。在此基础上对清管器及清管列车布置进行了优化设计,所设计的排水干燥列车由10个双向直板清管器组成(包含2段淡水段塞、2段水基凝胶段塞、3段三甘醇段塞和2段干空气段塞),最终提出了预投产工艺中所需的压缩机、增压机、干燥器等设备选型。应用效果表明,采用水基凝胶对排水干燥列车中三甘醇段塞进行密封隔水能有效保障荔湾3-1气田海底输气管道排水和干燥剂干燥效果;由空气驱动排水干燥列车可以一次性完成除盐、测径、排水与干燥。荔湾3-1气田输气管道干燥工艺施工取得令人满意的效果,为国内长距离、大口径深水天然气管线的排水干燥提供参考,对今后类似工程具有借鉴意义。

This paper studies the common drying methods according to the characteristics of shallow water landing pipeline in LW3-1 gas field. Drying method of triethylene glycol drying combined with air drying is chosen. Pig and location of the pig train are optimized based on the method. The dry train consists of 10 bidirectional pigs which including 2 fresh water slugs, 2 water-based gel slugs, 3 triethylene glycol slugs and 2 dry air slugs. The compressors, boosters and dryers used in pre production process are selected on the basis of dewatering and drying method. Results show that the effects of dewatering and drying gas pipeline can be effectively guaranteed in LW3-1 by using water-based gel to seal the triethylene glycol slug in dewatering and drying train against water. Propelled by dry air, the drying pig train completed the de- salting, gauging, dewatering and drying successfully in one single attempt. The successful implementation of pre-commission techniques of subsea gas pipeline in LW3-i is instructive for the drying of long large-di- ameter deep-water gas pipeline and it will benefit the future similar project.