Storms at sea – rising waves and worries for offshore operators

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After churning in the Gulf of Mexico last week, Tropical Storm Karen dissipated into the quiet of the night without so much as a blip on the radar screen in her final hours. Even before this storm created any kind of disturbance, many offshore operators, including several ImpactWeather clients, were paying close attention to weather reports and started to evacuate non-essential personnel.

Now, as companies like BP, Marathon and Chevron work to restore their platforms to full operation status, many wonder if it was worth halting nearly two-thirds of oil output in the U.S. Gulf of Mexico to remove personnel from a threat that eventually did not materialize to full force. Based on our study of how severe weather affects an offshore oil operation, those questioning the decisions of the oil operators might reconsider.

Rescue boat near offshore oil rigIt’s the mother of worst-case-scenarios: a “pop-up” hurricane that develops in the middle of the Gulf of Mexico, without warning or lead time, affecting rigs thousands of miles from the nearest shore line. These weather events can result in oil rigs being beaten and bent by heavy winds, piercing rain pelting their structure, and lightning rivaled by what Hollywood producers create for movies like The Perfect Storm. When a disturbance starts churning ever so slowly into a mega storm, the ImpactWeather operations department pays attention intensively because it can take anywhere from a few days to a full week for clients to evacuate rigs. Logistics for evacuations are so multi-faceted, that waiting until the final hours is never an option.

So, what happens to an offshore rig when a 157 mph hurricane comes barreling toward it? First, we must look at the three different types of drilling equipment that oil operators’ use, including shallow water elevated rigs, deepwater floating platforms and drill ships. The shallow water jack-up rigs can operate in up to 200 feet of water, and are typically raised 50 feet above the ocean’s surface. The deepwater floating platforms are the mega rigs in the middle of the ocean with 12 to 16 giant cables connecting the platform to the sea floor. The third, and most vulnerable, is drill ships, which are often located in deep water and attached to the sea floor via “risers.”

Each of these structures is at the mercy of a hurricane’s high winds and deadly waves. High winds can damage a rig’s cranes, communications antennae and lighter pieces of equipment that are not secured to the platform. They can also knock drill ships off-site if they do not disconnect from a riser in time. A drill ship that becomes dislocated from its moorings can create some considerable damage to nearby pipes on the sea bed, or worse, cause an oil spill.

Waves, however, are what do the most damage to the oil operators’ locations both above the ocean’s surface and deep below. Large hurricanes can generate waves tall enough to reach the shallow water rigs. Hurricanes Ike, Katrina, Rita and Ivan produced waves up to 100 feet tall. Jack-up rigs hovering only 50 feet above sea level barely stand a chance against a force that mighty. Waves can capsize drill ships, bend a shallow water rig’s metal posts, or submerge a platform. They can also cause extensive damage to underwater pipelines by causing landslides that shift the sea floor.

Operators discuss evacuation on helicopter landing pad offshoreIn 2008, Hurricanes Ike and Gustav destroyed 60 platforms with 31 of them needing three to six months of repair time. Hurricanes Katrina, Rita and Ivan did similar damage, with Katrina and Rita causing even more of a headache with the destruction of 101 pipelines.

Now, imagine if people had to shelter in place on these rigs because they couldn’t evacuate in time – clearly not an ideal situation for any offshore operator. People are the number one reason for the implementation of these safety precautions. When the deadline arrived for the decision to evacuate or not, operators will choose the safest route and evacuate without question to keep employees out of harm’s way. As destructive as recent hurricanes have been to offshore operators, they have also provided a wealth of learning experiences that contribute to the continual improvement of safety protocols.

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