Oil & Gas Case Study:

Offshore platforms in the North Sea

Extreme waves can damage oil and gas platforms. Our analysis suggests that future conditions influenced by climate change may render existing rigs unsafe according to present criteria. If so, decks should be raised and support jackets strengthened.

Our analysis

Using the DNV GL risk assessment framework we based our analysis on state of the art climate projections and wave simulations. We used these wave projections to estimate the risks for a platform typical of rigs in the North Sea, with deck heights about 20 metres above mean sea level. Specifically, we looked at the probability that waves will hit the upper side of the deck - called wave-in-deck.

Our findings

These results suggest that design modifications are needed. Two options were evaluated: raise the deck, so it is less likely to be reached by waves, or strengthen the supporting jacket, to increase resistance against collapse. Using our risk assessment framework we also carried out cost benefit analysis of both strategies to evaluate which is most cost effective and the extent to which it should be implemented. The figure above shows that the optimal deck raise is about two metres. The shaded area accounts for climate model variability.

Risk-based analysis of adaptation options

Offshore platforms are designed and constructed according to rigorous rules which guarantee compliance with safety criteria. These rules take into account environmental factors such as wave height and wind speed, but in a future climate these factors may change.

climate Models
Offshore Figure