Station-keeping systems must take into consideration local ice conditions, water depth and ice management support. In many Arctic regions of interest for hydrocarbon development, shallow water depths necessitate small vessel offsets, favouring designs that use moorings to maintain location. For developments in deeper water, larger offsets are permissible and dynamic positioning (DP) solutions may be a viable alternative. Experience gained by industry from past Arctic operations provides very valuable insights into station-keeping issues.
Disconnection systems currently available (for example, that used on the Terra Nova FPSO offshore Newfoundland), are designed to allow for emergency disconnection of the vessel to avoid possible iceberg impact. Lessons learned from the design and operation of these systems can be leveraged to develop turrets for heavier ice conditions, where new disconnection systems are required, to enable frequent operational disconnection and reconnection of a vessel under high ice loads.
The response of moored vessels in managed ice is an important area of research. Lessons learned from drilling operations onboard the Kulluk, which operated in the Beaufort Sea in the 1980s, are an important source of information.
For DP vessels, accurate prediction of the environmental loads acting on a vessel operating in dynamic ice conditions is a significant challenge. During the ACEX coring expedition in 2004, the Vidar Viking utilized dynamic positioning to keep station in broken ice, with ice management support from the Sovetsky Soyuz and the Oden. This expedition serves as an important source of information regarding the performance of DP vessels in managed ice, and serves to illustrate how multi-vessel ice management strategies can be effectively used to significantly reduce station-keeping loads in dynamic pack-ice conditions.