Automatic Ice-vaning Control for Arctic Offshore Structures’ Station-keeping

Abstract

The presence of sea ice is the main challenge for offshore structures and marine operations in the Arctic. It is generally accepted that Drillships, floating production units (FPUs), and floating production storage and offloading units (FPSOs) running operation in the Arctic obviously require the equipment for station-keeping as well as ice management action by icebreakers. Dynamic positioning (DP) system, which is nowadays widely used in marine operation in the open water condition, is one of the considering station-keeping method in the Arctic. The presence of sea ice adds complex external forces in the motion of the vessel which must be regulated by DP control action. In this study, an automatic ice-vaning control algorithm for Arctic offshore structures’ station-keeping without measurements or estimation of global ice load is proposed. This algorithm is compared with normal proportional and derivative DP control algorithm in ice drifting model tests which are composed of various ice concentrations. The differences between two control algorithms in various ice condition are discussed in this paper. And the feasibility of automatic ice-vaning control for station-keeping in managed ice is shown.