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Gulf of Mexico oil spill 2010: The worst-case scenario
By Ben Raines
April 30, 2010, 10:16AM
View full size(AP Photo/NASA)
This satellite photo made Thursday, April 29, 2010 and provided by NASA shows the oil slick in the Gulf of Mexico as it closes in on the Pass a Loutre area of Plaquemines Parish, La.
As the oil from the massive spill in the Gulf of Mexico was starting to ooze ashore Friday, officials told the Press-Register that the worst-case scenario could arise should a wellhead at the Deepwater Horizon rig site fail.
View full size(The Times-Picayune)Note: Read followup report with further information and explanation, including details of confidential government memo.
The worst-case scenario for the broken and leaking well gushing oil into the Gulf of Mexico would be the loss of the wellhead currently restricting the flow to 5,000 barrels -- or 210,000 gallons per day.
If the wellhead is lost, oil could leave the well at a much greater rate, perhaps up to 150,000 barrels -- or more than 6 million gallons per day -- based on government data showing daily production at another deepwater Gulf well.
By comparison, the Exxon Valdez spill was 11 million gallons total. The Gulf spill could end up dumping the equivalent of 4 Exxon Valdez spills per week.
"Typically, a very good well in the Gulf can produce 30,000 barrels a day, but that's under control. I have no idea what an uncontrolled release could be," said Stephen Sears, chairman of the petroleum engineering department at Louisiana State University.
Minerals Management Service data indicates that the deepwater Thunderhorse production platform, also owned by BP, has produced up to 150,000 barrels per day.
Thursday, federal officials said they were preparing for the worst-case scenario but didn't elaborate.
Kinks in the piping created as the rig sank to the seafloor may be all that is preventing the Deepwater Horizon well from releasing its maximum flow. BP is now drilling a relief well as the ultimate fix. The company said Thursday that process would take up to 3 months.
"I'm not sure what's happening down there right now. I have heard there is a kink in what's called the riser. The riser is a long pipe that connects the wellhead to the rig. I really don't know if that kink is a big restriction. Is that really a big restriction? There could be another restriction further down," said LSU's Sears.
"An analogy would be if you have a kink in a garden hose. You suspect that kink is restricting the flow, but there could be another restriction or kink somewhere else closer to the faucet."
BP executive Doug Suttles: said Thursday the company was worried about "erosion" of the pipe at the Deepwater Horizon wellhead. A new leak in that piping was discovered Wednesday, suggesting the erosion is worsening.
BP Plc executive Doug Suttles said Thursday the company was worried about "erosion" of the pipe at the wellhead. A new leak in that piping was discovered Wednesday, suggesting the erosion is worsening.
Sand is an integral part of the formations that hold oil under the Gulf. That sand, carried in the oil as it shoots through the piping, is blamed for the ongoing erosion described by BP.
"The pipe could disintegrate. You've got sand getting into the pipe, its eroding the pipe all the time, like a sandblaster," said Ron Gouget, a former oil spill response coordinator for the National Oceanic and Atmospheric Administration.
"When the oil is removed normally, it comes out at a controlled rate. You can still have abrasive particles in that. Well, now, at this well, its coming out at fairly high velocity," Gouget continued. "Any erosive grains are abrading the inside of the pipe and all the steel that comes in contact with the liquid. It's essentially sanding away the pipe."
The formation that was being drilled by the Deepwater Horizon when it exploded and sank last week is reported to have tens of millions of barrels of oil. A barrel contains 42 gallons.
"The loss of a wellhead, this is totally unprecedented," said Gouget. "How bad it could get from that, you will have a tremendous volume of oil that is going to be offgassing on the coast. Depending on how much wind is there, and how those gases build up, that's a significant health concern." |
