A dynamic catastrophe modeling methodology for deepwater drilling riser and new hang-off system

The new hang-off system is designed as critical equipment to reduce failure risks for risers in hang-off modes. However, drift of dynamically positioned (DP) platforms may trigger cascading failures, causing catastrophic consequences for the riser and new hang-off system. To quantitatively characterize the resulting catastrophic evolution, a dynamic catastrophe modeling methodology integrating event-node taxonomy and catastrophe mechanics is developed. The framework systematically describes the multi-event coupling process and identifies critical transition pathways in riser–platform interactions. A thirteen-event dynamic model incorporating DP drift, riser–moonpool contact, Lower Marine Riser Package (LMRP) touchdown, and hang-off joint failure is established and solved using coupled finite element and numerical approaches. Results demonstrate that unpowered DP drift (100 % thruster degradation) induces a severe catastrophe sequence: platform drift, buoyancy element–moonpool contact and crushing, articulation joint rotation to critical angle, and hang-off joint yield as the terminal event. Under 50 % thruster degradation, the riser and hang-off system remain structurally secure, confirming that maintaining partial thruster power is essential for safety. Seabed uplift with maintained thrust triggers top-section riser buckling following LMRP touchdown, highlighting the necessity of preventing LMRP contact. The proposed methodology establishes a quantitative theoretical framework for analyzing dynamic catastrophe evolution in risers.