流固耦合对油气井管柱振动特性的影响分析

以油气井管柱为例,分析了流固耦合作用对管柱振动特性的影响。首先建立了有无流固耦合管柱振动方程,阐述了考虑流固耦合对管柱振动特性分析的重要性。再应用ANSYSWorkbench软件建立有无流固耦合管柱三维有限元模型,运用Modal分析模块分析了空管柱、气固耦合管柱、液固耦合管柱三种情况下管柱的固有频率与振型等振动特性。与无流固耦合管柱振动特性对比表明:考虑流固耦合作用时管柱固有频率小于无流固耦合时空管柱的固有频率;与气固耦合相比较,液固耦合时管柱固有频率降低量更大,高达13%;管柱固有频率基本随阶数呈平方关系增长;管柱各阶固有频率均随管柱长度的增加而非线性下降;流固耦合作用对管柱的振型几乎没有影响。流固耦合作用影响管柱的固有频率,尤其是内部流体密度很大时,这种影响更不能忽略。考虑流固耦合作用下管柱振动特性的分析为管柱动力学分析提供了依据,也可为避免结构的共振提供参考。

Influence of Fluid-Solid Interaction on the Vibration Characteristics of Tubing in Oil and Gas Well

Influence of fluid-solid interaction(FSI)on the vibration characteristics of tubing in oil and gas well was investigated.The vibration equations of tubing considering FSI and not were established and the importance of FSI on the vibration characteristic of tubing was described.Three-dimensional models of tubing considering FSI and not were established in ANSYS Workbench software.The natural frequencies and mode shapes were analyzed for the cases of no FSI,gas-solid interaction,and liquid-solid interaction in the modal module of ANSYS Workbench software.It was found that natural frequencies of tubing decreased considering FSI compared with no FSI.The decrease is greater in the case of liquid-solid interaction compared with gas-solid interaction,which is about 13%.There are proximate square relationship between natural frequencies of tubing and the order.The natural frequencies will decrease non-linearly with the length of tubing.The mode shapes are almost unchanged when considering FSI.It shows that the influence of FSI can’t be ignored especially when the density of inner fluid is high.The research can provide references for the study of the vibration of tubing and the prevention of resonance.