Monday, April 26, 2010

Sunken Drilling Rig Leaking Oil

As most of you probably know, last week an oil drilling rig exploded, burned, and collapsed just off the coast of Louisiana. The rig was performing exploratory drilling at the time of the explosion. Most workers escaped, but 11 are still missing and presumed dead. The initial word was that leakage from the wreck had stopped after the rig sank and that environmental damage would be minimal.

It turns out that confidence was premature. Oil has been leaking from the damaged rig pipes at a rate of 1,000 barrels per day. (At that rate, it would take three days to classify as a major spill.) BP is trying to shut off the leak, but the likelihood of success is uncertain.
The best hope is that the remote-operated submarines—at least four are deployed at the scene--would be able to activate a huge device on the sea floor called a “blow-out protector,” a series of valves meant to control pressure in the well. “This is a highly complex operation,” said Doug Suttles, chief operating officer for BP’s exploration and production division. “And it may not be successful.”

If that operation fails, the next option is to drill a relief well—a process that would take at least two to three months, said Suttles. A BP rig equipped for this task is to arrive at the scene by Monday.

Suttles also said that the company was putting in place a plan to mitigate the potential damage by capturing the oil beneath the water surface. It’s an operation that involves lowering a large dome to trap the oil and pipe it to a holding vessel at the surface.

Although such a system was deployed successfully after Hurricane Katrina, Suttles said it has never been attempted at this depth. “We have the world’s best experts working to see if we can make that possible,” he said.
The oil slick is not expected to reach the coastal wetlands and beaches in the near term. However, changes in the wind or weather could move it towards land more quickly. The short term goal is to contain and disperse the slick.
The size of the oil spill appeared to be 600 square miles (1,500 square kilometers) as of Sunday, located 30 miles (48 kilometers) offshore, said Charlie Henry, scientist with the U.S. National Oceanic and Atmospheric Administration, a member of the response team.

Landry said that chemical dispersant also has been applied to the oil spill, and that the team was ready to apply more. She said a third of the world’s oil dispersant supply was available in the Gulf region.

According to the U.S. National Research Council, oil spill dispersants do not actually reduce the total amount of oil entering the environment. Rather they change the chemical and physical properties of the oil, making it more likely to mix into the water column than to contaminate the shoreline. “Dispersant application thus represents a conscious decision to increase the hydrocarbon load … on one component of the ecosystem… while reducing the load on another,” a 2006 NRC report said.
One of the worst drilling rig leaks in the Gulf Coast took nine months to fix in 1979. A drilling rig in the East Timor Sea leaked for months without a successful fix despite numerous attempts. So I hope the submersibles are successful in shutting off the pipes before this spill gets worse.

Map of the spill's extent and location as of April 25 (click through for a larger version)

Update: NASA's Aqua satellite captured an image of the oil slick, which appears as a silvery sheen in the image above.