Marine riser emergency disconnection analysis using scalar elements for tensioner modelling

• Analytical formulation is proposed for modelling tensioner behavior in global riser analysis.
• Formulation is implemented in commercial software (Orcaflex) through scalar elements.
• Model was calibrated and compared with literature results, showing adequate behavior.
• Some uncertainties around riser stretch and movement were observed.
• The proposed model is recommended for global analyses that require a more precise simulation of tensioner behavior.

This work proposes nonlinear parallel spring-damper scalar elements in series with a rigid beam element to represent drilling riser tensioner behavior during an emergency disconnection scenario in global riser analysis. The software package used was Orcaflex. This is a simpler approach than the more complex, full hydraulic-pneumatic-mechanic dynamic simulation modelling of the tensioning system, commonly used in literature, which can be time consuming and numerically more sensitive. The model can also be used to represent top tension variation in global riser analysis, allowing for more complex and precise simulations, especially for fatigue life and overpull estimations. The results show adequate agreement with the researched bibliography.