Although it appears that the badly listing Thunder Horse platform in the Gulf of Mexico may require extensive repairs after taking a severe beating by Hurricane Dennis, BP was taking an optimistic view on Wednesday. Meanwhile, other producers have nearly completed repopulating Gulf platforms and rigs, and the Minerals Management Service (MMS) has reported no other major damage to Gulf infrastructure. Gas production shut-ins have fallen to about 1 Bcf/d.
So far no damage to either Thunder Horse’s submerged hull or infrastructure on its deck has been found, the company said Wednesday, but workers were attempting to restore the facility to a level position before the potential arrival of Tropical Storm Emily in the Gulf early next week. The platform, which is located in Mississippi Canyon Block 778 about 150 miles southeast of New Orleans in 6,000 feet of water, is listing about 20 degrees and the bottom of its deck currently is in the water on one end, leaving it vulnerable to damage from high seas.
“We have certainly factored the possibility of another storm entering the area into our planning,” said BP spokesman Ronnie Chappel. He said teams currently are working rapidly to balance the platform and to determine the cause of the problem. It is uncertain at this time whether the ballast system that is used to keep the platform level was damaged.
Floating semi-submersible platforms are anchored to the sea floor over the location where oil and gas is drilled and produced. Like all semi-submersibles, Thunder Horse, which is the largest of its kind in the world, is equipped with a ballast system so that the level of the platform can be adjusted in the water according to the infrastructure on board. The four columns and connecting structure are partially submerged and anchored to the sea floor with 16 mooring lines, massive chains with nearly six-inch diameter steel links.
Chappel said there was “absolutely no evidence” that a 10-ton winch that was knocked overboard on Thursday during evacuation procedures broke any of the mooring lines or caused the platform to become unbalanced.
“At the time that we dropped the winch we went out and did inspections using a remotely operated vehicle (ROV) and found no evidence of damage,” he said. “On Tuesday, we completed an extensive survey of the submerged portions of the platform and found no indication of any damage to the hull.
“We took teams off last night at dark for safety reasons and to give the teams a rest. They went back today, and they are in the process of establishing the pumping operations required to right the platform. We have not determined why the platform is listing. We have teams of people who are analyzing the information from the data recording system in an effort to find clues that will help us identify a cause.
“It’s too early to know what the impact will be on this project’s schedule,” he added.
The massive $1 billion platform, built around one of the largest gas and oil discoveries in the history of the Gulf, was in a development phase when Dennis arrived. Production was scheduled to begin late this year. Thunder Horse has a nameplate capacity for 250,000 bbl/d of oil and 200 MMcf/d of gas. It was expected to reach those production levels over the course of the first 12 months of commercial operation.
Analysts are concerned about the potential for a service delay because of Thunder Horse’s tremendous payload and the current plight of the gas and oil markets, which have experiencing extremely high prices this week of more than $8/MMBtu and $60/bbl, respectively. “It would create a huge hole if for some reason they can’t get that thing back up and running,” said a spokesman for another major production company.
The MMS said Wednesday that no other significant damage was reported in the Gulf from Hurricane Dennis. “Our preliminary report is that the damage from Hurricane Dennis was extremely light,” said MMS Gulf of Mexico Regional Director Chris Oynes. “This was much lighter than Hurricane Ivan was last year. The eye of the hurricane was about 120 miles farther east than Ivan’s was in the deeper water sections of the Gulf and thus the impact to the platforms and rigs was minimal. The path of the hurricane carried it mostly over open water with no oil and gas operations.”
That path, however, did cause substantial waves and winds in the Mississippi Canyon area where Thunder Horse is located.
MMS said that Gulf production shut-ins as of 11:30 a.m. CDT on Wednesday had fallen to 1,030 MMcf/d of gas and 231,789 bbl/d of oil with only four manned platforms and two rigs remaining evacuated based on reports from 15 companies. Those totals are down from Monday’s peak shut-in level of 6.2 Bcf/d of gas and 1.4 MMbbl/d of oil. On Monday, 359 manned platforms and 86 rigs were evacuated out of a Gulf of Mexico total of 819 platforms and 134 rigs.
Cumulative production shut-ins due to Hurricane Dennis since last Friday have risen to 23.016 Bcf of gas and 5,220,149 bbl of oil, which are the equivalent of 0.631% of annual gas production in the Gulf and 0.953% of annual Gulf oil production, MMS said.
Producers now have to keep their eyes on Tropical Storm Emily, which the National Hurricane Center (NHC) said was expected to veer more west and south than originally expected and could hit Mexico’s Yucatan Peninsula by Monday morning. That trajectory means BP and the Gulf’s other producers may get a lucky break this time.
At 5 p.m. AST Wednesday, the center of Emily was located 135 miles east-southeast of Grenada and moving west at 18 mph. A turn to the west-northwest was expected in the following 24 hours. Maximum sustained winds remained at 60 mph but some strengthening was expected. The NHC said Emily was not expected to reach hurricane status before passing the Windward Islands.
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