ABSTRACT

Flexible risers that for deep-water production are designed with strong collapse capacity. However, this collapse capacity is susceptible to pipe curvature in the flooded annulus condition. For the curved riser sections within the touchdown zone, significant reduction of collapse capacity can occur once the external sheaths are worn out, resulting in the so-called ‘wet collapse’. Therefore, the collapse capacity of flexible risers should be well-determined during design stage. Mostly, curved collapse analyses are performed through costly numerical simulations since there is no well-established analytical models . This study focuses on the wet collapse mechanism of curved flexible risers, aiming to pave the way for the development of analytical solutions. 3D full FE models were adopted to gain insight into the wet collapse mechanism of curved risers, which had been verified by the data from public literature. The investigation indicates that the deformed cross-sectional shape of the carcass is the dominant factor of the curvature effect.

摘要

用于深水生产的柔性立管具有强大的塌陷能力。但是，这种塌陷能力在淹没环空条件下易受管曲率的影响。对于着陆区域内的弯曲立管部分，一旦外部护套磨损，则可显着降低塌陷能力，从而导致所谓的“湿塌陷”。因此，在设计阶段应确定挠性立管的倒塌能力。通常，由于没有完善的分析模型，因此通过昂贵的数值模拟来执行弯曲坍塌分析。这项研究的重点是弯曲挠性立管的湿塌陷机理，旨在为开发解析解决方案铺平道路。采用3D完整有限元模型来深入了解弯曲立管的湿塌陷机理，该机理已得到公共文献数据的证实。研究表明，胎体的横截面变形是曲率效应的主要因素。