Mechanical behavior analysis for the determination of riser installation window in offshore drilling

Abstract

The purpose of this paper is to figure out the safety operation window of riser in installation through taking three kinds of mechanical behavior. In this paper, the sea surface current velocity, surface wind velocity, wave height and wave period are taken as the evaluation factors of marine environment. The fleet angle at riser top section, the Mises equivalent stress on riser critical section, the axial dynamic load on riser bottom section and the riser transverse resonance are considered as the limiting factors which restrains the further complicacy of marine environment. Results show that the wave height and wave period mainly affect the lateral vibration frequency and the dynamic load. The sea surface wind velocity and sea surface current velocity determines the fleet angle and the Mises equivalent stress. However, compared with the fleet angle, the maximum equivalent stress is the main influence factor which limits the installation operation window. In general, under the circumstance of avoiding transverse resonance, smaller wave height and longer wave period are good for marine riser installation. The research has some reference value for safe and effective installation of marine riser.