Transitioning From Model-based To Data Driven Fatigue Analysis in Offshore Risers

Abstract

Offshore riser integrity management has traditionally relied on model-based fatigue analysis, where assumptions about environmental conditions and system behavior dominate. For design, this methodology remains the established and required approach, ensuring safety through well-defined theoretical models and conservative input parameters.

However, for life extension projects, an alternative route is emerging: the use of measured system behavior, such as vessel motions, riser motions, and strain, to complement or partially replace model assumptions. This shift reduces some uncertainties inherent to model-based assessments, while introducing new challenges related to real-world complexity and measurement reliability.

To explore the potential and limitations of this evolution, this paper presents three approaches for incorporating sensor data into the fatigue assessment workflow for offshore risers. The first approach introduces riser motion monitoring to calibrate numerical models against observed dynamics. The second replaces assumed vessel motions with measured data, reducing dependency on environmental approximations. The third and most advanced approach eliminates the need for a numerical model altogether by using topside motion, riser motion, and strain measurements to compute stress responses directly.

Through case studies from operational projects, we demonstrate how each step toward data integration improves prediction accuracy, reduces uncertainty, and supports proactive asset management. Results indicate that leveraging sensor data not only refines fatigue life estimates but also enables long-term trending and predictive maintenance, shifting monitoring from passive observation to an active decision-making tool. This progression aligns with industry goals of optimizing life of field performance while maintaining robust safety margins.

By comparing these approaches, the paper provides practical insights into implementation challenges, benefits, and the potential for digitalization to strengthen offshore integrity management. The findings underscore that while traditional model-based design remains foundational, the use of verified field data is key to achieving smarter, safer, and more sustainable life extension strategies.

Authors

Aurora Åsgård Pedersen
Engineer at 4Subsea

Bjørn Wilhelm Jæger
Senior Engineer at 4Subsea

Einar Steen-Johnsen
Engineer at 4Subsea