Preliminary Analytical Formulation of Ice-Floater Interactions Including the Effect of Wave Load

Abstract

Diminishing ice presence in the Arctic provides the potential for extended operable period for oil and gas exploration in the Arctic. Floaters are a flexible solution for such scenario whereas they can fully take advantage of the extended drilling season as well as operate in other harsh environment regions during the off-season. Such floaters can disconnect and reconnect to avoid large ice features such as icebergs and multi-year ice ridges. However, they still need to encounter relatively large level ice. Accompanying icebreakers will ideally assist in breaking the level ice into manageable pieces. The interaction of such level ice floes with floater has a significant influence on the dynamic ice load on the floater and resulting mooring load. There is significant uncertainty in the simulation of level ice-floater interaction numerically. Most of the current research focuses on the influence of ice breaking and subsequent flow of the broken ice around the floater. However, the hydrodynamic load due to the incoming level ice will also affect the response of the floater, which is usually not simulated. A recent study simulated the multibody hydrodynamics of level ice and floater Such multibody hydrodynamic analysis is computationally expensive, and complexity in the modelling is a hindrance to its implementation in the design phase. The present study, therefore, employs a conservative estimation to include the effect of wave load on the floater in addition to the ice load. Parametric studies are performed to estimate this effect by varying the incoming wave amplitude and wave period, ice sheet thickness, ice drift velocity, floater’s hull angle, mooring stiffness and the distance of large ice-sheet from the floater. Significant impacts of waves on the floater in terms of total force are observed which clearly reflects the importance of this study. The effect of mooring stiffness on total load is also investigated at the end of this study which can be considered as a foundation for further research on optimizing the mooring stiffness for such kind of arctic floater.