深水钻井隔水管-生产立管群干涉振动分析

Interference Vibration Analysis of Drilling Riser-Production Riser Clusters in Deep Water

当波浪、洋流流经钻井隔水管或生产立管时,管体和附近的流体会发生强烈的相互干涉作用,使其振动特征远比单管或者双管情况更为复杂。目前针对大雷诺数条件下,实尺寸钻井隔水管和生产立管群之间双自由度耦合干涉振动问题的研究还未见相关报道。为此,利用ANSYS-Fluent平台建立二维实尺寸钻井隔水管和生产立管群数值模型,采用SST k-ω模型和嵌套网格技术对流场域进行求解,并运用四阶Runge-Kutta法求解多管柱系统动力响应控制方程,通过自编流固耦合求解程序,实现流体与管柱之间相互耦合计算。研究结果表明:约化速度对钻井隔水管与生产立管群系统的干涉振动响应影响显著,在实际工程中,可以通过调节钻井隔水管或生产立管顶张力大小等方式改变其固有频率,或调节外形尺寸等方式改变约化速度,从而使管体脱离锁振状态,降低振动幅度;井槽间距的变化对柱群动态干涉响应的影响较小;立管群之间的干涉效应较双立管系统干涉效应有所差别,体现在中心位置的隔水管振动特性介于孤立状态和串列状态之间。所得结论可为海洋平台钻井隔水管与生产立管之间的干涉振动分析提供理论依据。

As waves and ocean currents flow through drilling risers or production risers,there will be strong interference between risers and nearby fluid,resulting in more complicated vibration characteristics than isolated riser or dual-riser system.There is no relevant report on the research of the two-degree-of-freedom interference vibration between full-size drilling riser and production riser clusters under the condition of large Reynolds number.Therefore,the ANSYS-Fluent platform was used to establish a two-dimensional full-size numerical model of drilling riser and production riser clusters,SST k-ω model and nested grid technology were used to solve the flow field,and the fourth-order Runge-Kutta method was used to solve the dynamic response control equation of multi-riser system.A self-programmed fluid-solid interaction solution program was used calculate the interference between fluid and risers.The results show that the reduced velocity has a significant influence on the interference vibration response of drilling riser and production riser cluster system.In practice,the vibration amplitude of risers can be reduced by adjusting the top tension of drilling riser or production riser to change its natural frequency or adjusting the dimensions of riser to change its reduced velocity so as to make the riser get out of the locked vibration state.The change of well spacing has little influence on the dynamic interference response of riser clusters.The interference effect between riser clusters is different from that of dual-riser system,and the vibration characteristics of risers in the center are between isolated state and tandem state.The conclusions provide a theoretical basis for interference vibration analysis between drilling riser and production riser of offshore platform.