The objective is to propose a quick and accurate vortex-induced vibration (VIV) model to predict the fatigue life of marine drilling risers. The nonlinear wake oscillator model was applied to represent the lift force, which is described by a fourth-order partial differential equation set. Next, we adopted the generalised integral transform technique (GITT) to transform it into second-order ordinary differential equation system, which was solved by the Runge-Kutta method. Validation of the numerical model was implemented and a good agreement was achieved. Next, an S-N curve was adopted to conduct fatigue prediction. The results demonstrate that under the conditions set forth in this paper, an increase in the current and outer diameter could reduce fatigue life, except when the outer diameter reaches a certain value, at which point the tendency is reversed. Moreover, when the top tension coefficient reaches a certain value, the fatigue life tendency is also reversed.

Subsea production systems (SPSs) have dominated the exploration of oil and gas resources in deep water; however, failure of SPSs can lead to enormous economic loss, serious environmental pollution and even severe casualties. Hence, the safety and reliability of SPSs have become a major concern. To guarantee the high integrity of SPSs, investment should be made in inspection and monitoring of SPSs (IMSPSs) in order to prevent failures of the subsea equipment, as much as possible. This paper reviews the current progress in technologies for IMSPSs using non-destructive testing (NDT). The basic principles and features of four common NDT techniques used for IMSPSs are reviewed. Based on these NDT techniques, the current development of IMSPSs, as well as the latest advanced technologies, is then discussed. Furthermore, capabilities and limitations of IMSPSs are discussed. Finally, suggestions for future development of IMSPSs are provided.