Floating Production Platform for Polar Seas Designed to Resist Iceberg Impact

Nowadays selection of ice-resistant platform for middle sea depth (from 200 to 400 m) is a vital problem for development of the Russian shelf (the Barents Sea, Sakhalin, etc.). According to the previous analysis the cost efficient way is to use a floating substructure like TLP, SPAR or Semi-submersible. However, traditionally mentioned above platforms are considered as non-suitable for ice conditions due to their unacceptable behaviour against ice impact. In the same time TLP and SPAR type substructures are considered for operation in ice conditions but shall have mooring (anchoring) system specially designed to withstand the ice impacts. Specifically actual problem for Shtokman field (the Barents Sea) is drifting icebergs that cause highest risks for the platform safety. SPAR type substructure with only flexible risers may be treated as an acceptable construction even in case of iceberg impact risks - provided certain innovations are implemented - and this is the subject of this paper. The paper provides comparison of various mooring systems for SPAR platforms and assessment of the ultimate resistance of the mooring system against global iceberg impact (or a huge grounded hummock) depending on its weigh and drifting speed.