深海安装工况下水下采油树鹅脖连接器安全性能分析

Safety performance analysis of subsea Christmas tree gooseneck connectors under installation conditions in deepwater

鹅脖连接器被广泛应用于水下采油树等结构物之间的软管连接。其深海安装作业风险高、要求严,因此研究鹅脖连接器安装工况下的安全性能对确保水下采油树乃至整个水下生产系统的平稳运行具有重要意义。针对南海某1500 m水深气田使用的采油树鹅脖连接器深海安装工况,对软管首末两端的鹅脖连接器进行有限元分析确定应力集中区域,并基于ISO标准施加1.5倍设计载荷对连接器高应力区域进行应力集中验证。结果表明:连接器各部件最大Von Mises应力均小于许用应力,整体结构强度满足相关标准要求;高应力主要集中在吊耳、提升外框的底板和锁板以及软管接头,在设计时应予以重点关注;此类区域最大主应变和等效塑性应变均满足标准要求。现场安装结果表明,末端鹅脖连接器与软管接头的静态载荷实测值远小于极限载荷,整个海上安装及水下连接安全可靠。本文研究成果可为水下采油树鹅脖连接器的结构设计和深海安装提供参考。

Gooseneck connectors are widely used for flexible pipeline connection between subsea Christmas trees and other subsea structures.Its deepwater installation poses high risks and strict requirements,so it is of great significance to study the safety performance of gooseneck connector under installation conditions to ensure the smooth operation of the subsea Christmas tree and even the entire subsea production system.According to the deepwater installation condition of the Christmas tree gooseneck connector used in a 1500 m deep gas field in the South China Sea,finite element analysis was performed on the gooseneck connectors at two ends of the flexible pipeline to determine the stress concentration area,and 1.5 times of the designed load was applied to verify the stress concentration in the high-stress area of the connector based on the ISO standard.The results show that the maximum Von Mises stress of each component of the gooseneck connector is less than the allowable stress,and the overall structural strength meets the requirements of relevant standards.The high stress of gooseneck connector is mainly concentrated in the lifting lug,the bottom plate and lock plate of the lifting frame as well as the flexible pipeline joint,which should be cautioned in the design.The maximum principal strain and equivalent plastic strain in such regions meet the standard requirements.The field installation results show that the measured static load of the end goose neck connector and flexible pipeline connector is far less than the limit load,and the whole offshore installation and subsea connection are safe and reliable.The research results in this paper can provide a reference for the structural design and deepwater installation of subsea Christmas tree gooseneck connector.