May 3, 2010
SUMMARY
Gulf of Mexico Deepwater Horizon Oil Spill 2010
Source: The New York Times
Updated: May 3, 2010
On April 20, 2010, an explosion aboard the Deepwater Horizon, a drilling rig leased by the oil company BP, set off a blaze that killed 11 crew members. Two days later, it sank about 50 miles off the Louisiana coast and crude oil began streaming out of a broken pipe attached to a well that the rig had been drilling nearly a mile below sea level.
Attempts to shut down the flow, at first estimated that at about 42,000 gallons of oil a day, failed when a safety device called a blowout preventer could not be activated. On April 28, government officials said the oil was leaking at a rate five times greater than the initial estimates.
As BP and federal officials scrambled for solutions, oil began washing ashore on the fragile Louisiana coast and drifting toward the shores of Alabama and Florida. On May 2, President Obama visited the scene of what he called a “potentially unprecedented environmental disaster.”
The Deepwater Horizon was described before the accident as one of the most technologically advanced drilling platforms in the world. The rig had drilled a well in the sea floor and was in one of the last phases of the operation, building a cement casing to reinforce the well.
There is still no explanation for what set off the explosion on the night of April 20, setting off an intense blaze that sent enormous plumes of flame shooting into the air. Most of the 126-member crew escaped; three were critically injured and the bodies of 11 workers were not recovered.
Initially the oil leaking out of the riser pipe from the sea floor was largely consumed in the fire. But when the rig collapsed and sank two days later, it began to form a slick on the waters above.
BP's engineers sought to cut off the leak by activating a towering stack of heavy equipment 5,000 feet below the surface of the gulf known as a blowout preventer. It is a steel-framed stack of valves, rams, housings, tanks and hydraulic tubing that is designed to seal the well quickly in the event of a burst of pressure.
It did not work, for reasons that are still not clear.
After that, the Coast Guard tried out a controlled burn of the slick, but found that the oil was spread too thinly in most of the spill for the technique to be effective.
By April 28, BP officials had identified three separate leaks, and had increased the estimate of how much oil was spilling to 5,000 barrels, or about 200,000 gallons a day. In the worst oil disaster in American history, in 1989 the Exxon Valdez tanker spilled more than 10 million gallons of oil after running aground in Prince William Sound in Alaska.
On April 29, Mr. Obama announced that the federal government would get involved more aggressively in fighting the spill, and Homeland Security Secretary Janet Napolitano designated the spill as "of national significance.''
The response effort has been driven by BP, under the oversight of the Coast Guard and in consultation with the Minerals Management Service and the National Oceanic and Atmospheric Administration. Federal officials said the Navy stood ready to help as needed.
BP was leasing the rig from Transocean, which also owns the blowout preventer.
The White House announced on April 30 that the government would not allow any new offshore drilling until an investigation was conducted into the spill and whether it could have been prevented.
The deadly explosion and the resulting spill have complicated Mr. Obama's recently announced plans to expand offshore oil and gas drilling, with some politicians and environmental advocates calling on the president to halt any planned expansions until more safeguards are put into place against future disasters.
On May 2, BP engineers described an audacious plan to confront the blowout preventer problem. In this approach, they would seal the well by cutting the riser at the wellhead, sliding a huge piece of equipment called the riser package out of the way and bolting a second blowout preventer atop the first one.
The risk in attempting such a maneuver — which would be performed, as all the undersea work has been, by robotic submersibles tethered to support ships 5,000 feet above — is that the pressure of the oil rising from the well could be overwhelming, and the well could gush oil at a far higher rate.
BP also planned to drill relief wells, which would allow crews to plug the gushing cavity with heavy liquid. Drilling of a first relief well was set to begin as soon as the weather cleared, with drilling for a second well was expected to begin in two weeks. The relief wells, however, will take months to execute.
In the meantime, crews were injecting chemical dispersant into the oil as it flowed from the main leak. Dispersant, which is more conventionally used on the water surface, breaks the oil into small droplets and reduces its buoyancy, so it will sink to the bottom.
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