phase 4 report - DNV

RN06: ICE MANAGEMENT – STATE OF THE ART REPORT // Ice ManagementBarents 2020Figure 2-2 Example of sea ice arrival at Shtokman (darker colour indicates higher ice concentration)Icebergs are rare on the Shtokman field, butnevertheless can occur, also south of Shtokman.Icebergs may drift in open water or within sea ice(where they are more difficult to detect and manage).Icebergs have a strong seasonal presence, withFebruary to July being typically the months with themost icebergs present as shown in Figure 2-3. Theprobability of encountering icebergs at Shtokman inthe period between late autumn and early spring islower than for the rest of the year, but it still exists.Table 2-2 shows the International Ice Patrolclassification of icebergs sizes and their probabilityof occurrence in the Barents Sea. It indicates theimportant fact that 76% of all icebergs are bergybits and smaller. The probability of iceberg impacton FPU, if not managed, has been estimated as oncein 250 years. The probability of iceberg contact withthe FPU Mooring System, if not managed, has beenestimated as once in 900 years. Iceberg drift speed,including meanders, is given in Figure 2-4.Figure 2-3 Monthly mean significant wave height and the probability of occurrence of icebergs at ShtokmanReport no 2012-0690 219