Ice induced platform motions

The first time in the Bohai sea and the yellow sea in China vibrations on platform were observed in-situ due to the movement of ice packs around the platform The dynamic loads affect not only the routine operation of an offshore platform such as drilling and production activities, but also the safety and serviceability of the structure. It is indispensable to reducing the overall response of a jacket platform subjected to strong dynamic loads. In general, reduction of the dynamic stress amplitude of an offshore structure by 15% can extend the service life over two times, and can result in decreasing the expenditure on the maintenance and inspection of the structure.

Met-Ocean conditions

Many of the deep water areas offer through their location considerable met-ocean challenges. As an example, the deep water Gulf of Mexico has substantial surface currents (“Loop current eddies”) with speeds sometimes in excess of 3.5 knots. The intensity of hurricanes in the area has increased, possibly related to a bifurcation of the Warm Gulf Stream, looping back into the GoM and causing the sea water to become much warmer. Strong bottom currents and subsurface waves are present. Similar aspects are found in the Southern Atlantic with both currents as well as very long period swell conditions. These currents and sub-surface waves can create unexpected forces and vibration induced fatigue on vessels, risers, moorings, and sub-sea equipment. Large scale meteorology, oceanology and climatology research is needed to enable more fundamental understanding of the physics of deepwater currents. This would improve the numerical modelling and thus improve forecasting and response based design criteria development.

Extreme wave impact on offshore platforms and coastal structures

Dynamic positioning evaluation study