Abstract

The search for hydrocarbons in deep Arctic waters requires the use of drillships and floating production units (FPUs). Typically, these units require protection by using ice management, e.g. icebreakers battling large ice floes followed by icebreakers downstream that cut the ice into smaller pieces just in front of the drillship or FPU. The essence of such operations is to reduce the ice actions on the protected units by changing the ice conditions. One of the challenges facing the designers of Arctic offshore structures is to quantify the reduction of the ice loads as a function of the managed-ice conditions. Design codes and available models in the literature may provide good bases to calculate level-ice actions on floating structures where the interaction process is typically divided into several phases: breaking, rotating, sliding and clearing of ice. However, the situation is different when the floating structure interacts with ice floes in a managed-ice field, i. e., large ice floes may behave similar to level ice while smaller floes may split and the very small ones will mostly be deflected, rotated or submerged. In case of moored structures the relative velocities between the structure and ice are small and this may lead to ice accumulation upstream the floater. In 2011, the authors of this paper proposed a numerical model to simulate the interaction between managed-ice and floating structures. Over the last three years, considerable developments to the model have been carried out at the Norwegian University of Science and Technology (NTNU) hosting a research-based innovation centre: Sustainable Arctic Marine and Coastal Technology (SAMCoT). This paper provides a short summary of these modelling efforts and highlights the major recent development performed at NTNU that enables the industry to operate more effectively and safely in Arctic waters.

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