Influence of the Heave Motion of a Floating Drilling Platform on the Crossflow Vortex-Induced Vibration of the Deepwater Drilling Riser

Abstract

Summary The study of vortex-induced vibration (VIV) characteristics of deepwater drilling risers is of great significance for correctly evaluating the risers’ fatigue life. Aiming to determine the VIV response of a deepwater drilling riser under the combined action of the heave motion of the floating drilling platform and sea current, this study established a mechanical model and governing equation of crossflow vortex-parametric vibration (CFVPV) based on the Van der Pol wake oscillator and Euler-Bernoulli beam. For this model, the governing equation is discretized in the time domain by applying the finite element method (FEM), and the equivalent integral form of the differential governing equation is obtained by the Galerkin method, and then solved using the Newmark method. On this basis, the influence of both the heave motion of the floating drilling platform, including the top tension fore, amplitude, and frequency, and the current profile on the CFVPV are analyzed in detail. The results show that the mechanical model and analysis method can be used to assess the CFVPV of deepwater drilling risers with high calculation accuracy. When considering the heave motion, the amplitude of the CFVPV response increases significantly, and more components of the vibration frequency appear. Moreover, the CFVPV displacement decreases with the top tension coefficient and heave motion frequency, while increasing with heave motion amplitude. It was found that the heave motion frequency changes the vibration amplitude and mode of the CFVPV, the effect of which was more obvious for the middle and lower parts of the riser. In addition, increasing the flow velocity reduces the effect of the heave motion. Finally, the CFVPV response at both ends of the riser was greater than that at the middle of the riser under the same flow velocity.

Influence of Auxiliary Pipelines of the Deepwater Drilling Riser on the Dynamic Characteristics of the Subsea Wellhead

“…Chen et al [24] established an analysis method to determine the safe operation window of the deepwater riser based on the allowable offset of the drilling platform in different directions. Wang et al [25][26][27][28][29][30][31] established a systematic analysis method for the mechanical behavior of the deepwater drilling riser under complex marine environments and drilling loads, which provided a scientific basis for the design and control of the deepwater drilling riser. The mechanical analysis on the riser system, including static analysis, vibration analysis, and recoil analysis, is related to the resilience issue.…”

Modal state vectors of a free-hanging drilling riser during deployment and retrieval

“…Compared with the riser fixed on a subsea wellhead, the hang-off drilling riser encounters more significant challenges and undergoes more severe dangers, for instance, more drastic dynamic responses, more massive rotation and deflection, a higher probability of striking, and severer fatigue damage or buckling. Especially when the frequency of vessel motion, wave loads, or vortex-induced vibration is close to the hangoff drilling riser's natural frequency, riser resonance is likely to be excited (Li et al 2005;Zhang and Gao 2010;Wang et al 2022), and disastrous consequences, for instance, environmental pollution and economic loss (Fan et al 2017;Chang et al 2018) are likely to be caused. To extract sufficient mechanical characteristics and fully analyze the dynamic behaviors for prevention of the riser's potential threats, modal state vectors such as natural frequency, modal displacement, slope, bending moment, and shear of the riser are thus urgently needed to be studied in detail.…”