Critical collapse pressure of flexible risers in deep/ ultra-deep water: a literature review

In this paper, the recent advances on collapse studies of flexible risers are reviewed. Collapse refers to radial buckling of flexible riser caused by excessive hydrostatic pressure. Since there is a constant push from oil & gas industry to extend deepwater exploitation beyond 3000m, hydrostatic collapse has been one primary challenge facing the riser operators. Riser collapse is a complex phenomenon related to material properties, geometry of the pipe and its overall surface topography and, therefore, leads to inherent unpredictability of the exact collapse pressure. Collapse prediction approaches of flexible risers have been developed for decades, yet a comprehensive review on their predictive capabilities, efficiency and drawbacks is lacking. This paper concentrates on these collapse predictive techniques of flexible riser in ultra-deepwater fields and the current gaps that exist in offshore technology, aiming to help develop the current anti-collapse design and be a baseline for future utilization of flexible risers in deeper water expansion.