Dynamic modeling and vibration analysis of the casing string system considering FSI inside and outside the casing

It has important guiding significance for the parameter design and field application of the vibration cementing equipment to reveal the dynamic behavior mechanism of the casing string system. However, there is a lack of models to describe the FSI dynamic behavior of the casing string system. Therefore, the FSI 16 equations model that describes the axial, lateral, and torsional vibration of the casing string system is established by the transfer matrix method (TMM) in this study. Then, the correctness and accuracy of the model is verified by comparison with previous studies, modal hammer tests, and finite element method (FEM). Finally, the casing string system whose length is 100 meters is taken as an example, the results show that the most significant parameter affecting the resonance peak's frequency of the casing string system is the fluid pressure. The fluid velocity and damping factor have a significant inhibitory effect on the resonance peak value of the casing string system. The fluid pressure and fluid velocity weaken the influence of support stiffness on the resonance frequency of the casing string system. The suppression of the vibration response can be avoided when the vibration cementing operation is performed during the fluid is stationary or at low flow rates. This study provides theoretical support for the calculation and analysis of the dynamic behavior for the casing string system.