Analytical assessment of the drilling risers stability in the Newfoundland deep offshore

Etido Gideon Akpan, Xiaoyu Dong, Mohammad Javad Moharrami, Hodjat Shiri

In the proceedings of: GeoSt. John's 2019: 72nd Canadian Geotechnical Conference

Session: Offshore and Nearshore

ABSTRACT: Marine drilling risers are amongst the key structural elements in deepwater oil and gas exploration projects. These risers are continuously subjected to dynamic environmental and operational loads. This has caused the drilling risers to be vulnerable against the fatigue loads. In this study, an analytical model was adopted by solving the governing differential equations to analyze the effect of Vortex-induced vibration (VIV) on the strength and stability of an arbitrary drilling riser operating in the Offshore Newfoundland. The case study showed that the amplitude of first-order dynamic oscillations is larger than that of higher-order responses. However, the higher-order responses can cause noticeable dynamic moment and shear force. The natural frequency of risers was found to decrease with increasing the water depth and increase for higher magnitudes of top tension. The analytical approach was found to be an appropriate solution for early assessment of the drilling riser fatigue life due to vortex induced vibration.

RÉSUMÉ: et gazière en eau profonde. Ces colonnes montantes sont continuellement soumises à des charges environnementales et opérationnelles dynamiques. Cela a rendu les colonnes de forage vulnérables aux charges de fatigue. Dans cette étude, un modèle analytique a été adopté en résolvant les équations différentielles régissant l'analyse des effets des vibrations induites par vortex (VIV) sur la résistance et la stabilité d'une colonne montante de forage arbitraire en exploitation au large de Newfoundland. L'étude de cas a montré que l'amplitude d'oscillation dynamique du premier ordre est supérieure à celle des réponses en mode d'ordre supérieur. Il a également été observé que l'effet du moment dynamique et de la force de cisaillement des modes d'ordre supérieur pourrait être important. avérée être une solutivortex induit des vibrations.

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