The many faces of the GOM

Think there’s just one Gulf of Mexico? If you’re talking hurricanes and the energy industry think again: there are now four.
New research on storm patterns has led the industry to divide the Gulf into four regions based on the intensity of the storms that occur there. The deciding factor in intensity is ocean currents and how much warm water they keep circulating to feed storms. At a panel at the OTC Tuesday called “Storm Warning,” a collection of engineers from throughout the industry discussed the findings and how they’ve changed the way rigs and platforms should be designed.
The Western Gulf to the 94th meridian (which includes Houston) has shown a lower probability of stronger storms. It’s being referred to as the “Eddy Graveyard” since currents that curl off from the Loop Current in the central gulf tend to drift down toward Brownsville to die off.
Strong storms are more frequent between the 94th and 90th meridians, an area labeled “Random Eddies.” The “Central Region,” which includes New Orleans, runs from the 90th to the 86th meridian and is essentially Ground Zero for the strongest storms. The Loop Current in that area keeps feeding storms with warm water, instead of cooler water from far below the surface that would take some of the strength out of storms.
From the 86th meridian East storms become less powerful (generally) in an area labeled as “Occasional Loop Currents.”
Katrina and Rita were in the Central Region, part of the reason for their intensity.
Of the 110-plus platforms that were destroyed by Katrina and Rita, 54 were built prior to 1969, the first year the industry published recommended standards for construction. Another 25 were built between 1970 and 1979, while rigs and platforms built between 1980 and 1989 seemed to fare better, with just nine destroyed.
There was a spike in destruction for platforms built between 1990 and 1999, with 15 destroyed, but Frank Puskar, President of Energo Engineering said that was likely because companies were given the leeway to build facilities to lower standards based on how critical the construction was to their operations.
One of the biggest determinants of whether a facility was damaged or destroyed? Whether waves crested either at or above the level of the lowest deck of the platform, Puskar said. Even if waves were just hitting a so-called “basement deck” that was just used for maintenance, the chance of failure was much greater.
Some of the construction standards have been revised since the 2005 hurricane season, but many more updates are expected soon. The result may be different standards for rigs and platforms depending on where they are located in the Gulf.
Here’s a link to a basic description of currents in the Gulf from the Minerals Management Service.