In the aftermath of recent hurricanes that passed through the Gulf of Mexico, the America Petroleum Institute (API) is making recommendations for assessing the behavior of existing deepwater floater installations. The API has issued interim guidelines including new environmental criteria and procedures to ensure continued safety of these installations. In accordance with the API interim recommendations, a set of metocean conditions has been defined for different regions in the GoM. In general, environmental design conditions have increased and will have an effect on the response of the floaters currently installed. Three of the most common types of deepwater floaters in the GoM are the semisubmersible, the TLP, and the spar. Responses of these designs, including motions, air gaps, and riser and mooring tensions, will have to be reexamined for these new criteria. The original designs are based on environmental criteria now are superseded by new criteria based on observed conditions during Hurricane Katrina in August 2005. The following compares results of predicted responses based on pre-Katrina data, which presumably were used to design the existing structures criteria, to those of the post-Katrina environments. The results compare the responses of typical, but fictitious, designs of an extended tension leg platform (ETLP), deep draft semi (DDS), and a spar hull.
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