In the next few years, marine vessels are expected to considerably increase their activities due to the beginning of offshore hydrocarbon field construction under "Sakhalin-l" and "Sakhalin-2" Projects. Oil production complexes will be designed for each offshore field. They will include several basic facilities such as:
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conventional ice-resistant platforms
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subsea pipelines
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onshore facilities
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subsea loading terminals
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subsea wellhead templates
Basically, problems of securing continuous operation of oil and gas production complexes will be associated with the existence of ice cover.
Depending on winter severity, ice appears on the northeastern Sakhalin offshore in mid-November or late November and disappears in mid-June. Ice concentration m this region reaches 9–10 points in late January. Persistent hummocking and grounding of hummocks is observed in February on the background of level ice thickness growth. Ice cover parameters reach their maximum values in March-April (Table 1). Heavy ice belt exists in this time period within the close floating ice zone. This heavy ice is formed in western Okhotsk Sea (The Shantar Islands), upon compacting and consolidation m Sakhalin Bay it is driven to the area of offshore oil and gas fields. The heavy ice belt is 15–40 km in width and does not include giant and vast ice floes. Ice massif itself is noted for large vertical thickness and hummocking (Polomoshnov et al., 1990). A flaw polynya 20–40 km in width is observed in this region annually in April-May. Comparative analysis of ice cover parameters for the Arctic seas and Sakhalin offshore oil and gas field area indicates that they differ only slightly and the Okhotsk Sea may be positively classified among the Arctic seas.
