3D Nonlinear Flow-Induced Vibration Model of Tubing Strings in High-Pressure, High-Temperature, and High-Yield Curved Gas Wells

In view of the fatigue failure of tubing strings by flow-induced nonlinear vibration (FINV) in high-temperature, high-pressure, and high-yield (3H) curved gas wells, a three-dimensional (3D) FINV model of the tubing string is established using the micro-finite method, energy method, and Hamilton variational principle, which takes into account the self-weight changes of wellbore trajectory, wellbore temperature/pressure, and contact/collision of tubing-casing. In order to solve the FINV model accurately, The Lagrange and cubic Hermite functions are used to discretize the governing equations, and the incremental form of Newmark and Newton-Raphson are used to solve the FINV model of tubing string. A similar experiment of tubing vibration is designed and completed to test the validity of the FINV model by comparing the frequency-domain and time-domain responses of the experiment with those from the proposed model. The analysis shows that the FINV model has good calculation accuracy and the vibration response law is basically consistent with the experimental results. Meanwhile, the vibration characteristics of the tubing string are analyzed by using the field well parameters in South China Sea, and the effectiveness of the proposed model is verified again. The research results can provide an effective theoretical analysis tool for FINV behavior of tubing string in 3H curved gas wells.