深水钻井隔水管横向振动振型分析

Analysis of Transverse Vibration Mode of Deep-water Drilling Riser

为了分析深水钻井隔水管的横向振动固有频率和振型,综合考虑深水隔水管受到的顶部张紧力、海洋环境载荷、钻井平台漂移等作用力,借助微元法建立受力分析模型。根据连续梁理论和隔水管单元的动力学微分方程,确定其无阻尼自然振动基本方程,并进一步剖析建立隔水管横向振动固有频率微分方程和模态振型基本方程,然后进行数值求解。使用控制变量法逐步分析隔水管长度、张力比、自身材质对隔水管固有频率的影响和变化规律。通过MATLAB软件表现出不同阶数的振动振型,结果表明:控制张力比、合理选择隔水管类型能够有效提高固有频率,避免与波流力形成共振,进而保证深水钻井作业安全。此外,隔水管的振型并不是标准正弦曲线,振型会受时间的影响不断变化。

For purpose of analyzing both natural frequency and mode of transverse vibration of the deep-water drilling riser,many forces such as the top tension force,marine environment load and the drift of drilling plat-form were comprehensively considered and their force analysis model was established based on the infinitesi-mal method.Through basing on continuous beam theory and the dynamic differential equation of the drilling riser,the basic equation of un-damped natural vibration was determined,and the differential equation of natural frequency and the modal shape's basic equation of the drilling riser's transverse vibration were further analyzed and established,and then the numerical solution was carried out.In addition,having the control variable method adopted to analyze the influence of the drilling riser's length,tension ratio and material on its natural frequency and change rule was implemented,including having vibration modes at different orders displayed through MATLAB software.The results show that,controlling the tension ratio and reasonably selecting the riser types can effectively improve natural frequency,avoid resonance with wave current force and ensure the safety of deep-water drilling operation.In addition,the drilling riser's vibration mode isn't a standard sinusoidal curve,and the vibration mode changes constantly under the influence of time.