基于流固耦合的水下发球管汇力学及振动特性分析

水下发球系统具有可利用生产流体发球、不停井发球的优势,在现阶段与未来海洋油气开发具有广阔的应用前景。水下发球管汇结构复杂,存在多处弯管、变径三通,生产流体压力高,而发球流程工艺引起的管汇结构变形与振动情况尚不清晰。本文采用数值模拟的方法,计算了某水下发球管汇在发球工况中,流固耦合条件下管汇结构的位移、应力分布及振动情况。发现阀门的开关瞬间是压力变化幅度最大的特征时刻,也是引起管道位移、振动情况最严重的特征时刻； 明确了管道结构风险位点为管汇结构末端,最大位移约为5.69 mm,主要由X方向贡献,最大等效应力为233.13 MPa,主要集中分布在T型管、弯管内侧处；提出了针对性的优化支撑方案,管汇结构最大位移降低至3.53 mm,低阶模态频率增幅约为1.74%~20.54%,说明管汇结构的安全性得到了提高。所得结论可为水下发球管汇的设计、运行提供理论依据。

Study on mechanical and vibration characteristics of underwater pigging manifold based on fluid-structure interaction

The underwater pigging manifold system has the advantage of utilizing production fluid pigging and non-stop pigging, which has a broad application prospect in the current and future offshore oil and gas development. The structure of underwater pigging manifold is complex, there are many bends and reducing tees, and the production fluid pressure is high. However, the deformation and vibration of the underwater pigging manifold structure caused by the pigging technology is still unclear. In this paper, the displacement, stress distribution and vibration of an underwater pigging manifold under fluid-structure coupling condition were calculated by numerical simulation. It is found that the valve switch is the characteristic moment with the largest range of pressure change, and also the characteristic moment that causes the most serious displacement and vibration of pipeline. It is clear that the risk site of pipeline structure is the end of manifold structure, the maximum displacement is about 5.69 mm, which is mainly contributed by the X direction, and the maximum equivalent stress is 233.13 MPa, which is mainly distributed at the inside of T-shaped pipe and bend pipe. The optimal support scheme is proposed. The maximum displacement of manifold structure is reduced to 3.53 mm, and the increase of low-order modal frequency is about 1.74%~20.54%. The safety of manifold structure is improved. The conclusions can provide theoretical basis for the design and operation of underwater pigging manifold.