By Marian Wang, ProPublica.
Last month's Deepwater Horizon oil spill has been followed by huge amounts of reporting. Here's our attempt to distill the information, and to focus on the more nebulous, unanswered questions of why it happened, whether it could've been prevented, and who's on the hook for the disaster.
What are the basics of what happened?
On the night of April 20, the Deepwater Horizon oil rig had an explosion, and two days later, it sank in the Gulf of Mexico. Eleven workers are missing and presumed dead. The rig was operated by British oil giant BP but owned by Transocean, the world's largest offshore drilling company. The incident ruptured the oil well and has caused what is known as a blowout, or an uncontrollable spill. The well has since spewed millions of gallons of crude oil into the Gulf of Mexico.
What caused the incident?
That's still being investigated. A drilling procedure called "cementing," which is meant to secure the walls of a well, has often caused blowouts in the Gulf, according to a 2007 study, and it's a suspected cause in this case.
Halliburton was the subcontractor handling the cementing process on the Deepwater Horizon rig, which it completed shortly before the explosion. It has been under scrutiny for its role in potentially causing the blowout.
So we don't know what caused the initial fire, but is there anything that could've stopped the spill?
The spill occurred when a safety device called a blowout preventer failed to stop the flow of oil from the well. The Wall Street Journal, which has had great coverage of the disaster, reported that federal regulators had questioned in 2004 whether an "integral" part of the blowout preventer—a piece of equipment known as shear rams—would work in deep-water conditions. The Deepwater Horizon rig was drilling in about 5,000 feet of water, and the device obviously did not do the job.
Despite their concerns about the shear rams, regulators from the Minerals Management Service–the agency that regulates offshore drilling—did not issue new regulations to strengthen industry requirements, according to the Journal.
The Journal also reported that another device–one that the BP's rig lacked–was a backup shutoff device called an acoustic switch that is used by some other oil-producing countries. MMS regulators had once considered requiring the acoustic switch. But after the industry spoke out against it, MMS backed down and simply recommended that the matter be studied.
So the spill wasn't prevented. Could cleanup and containment efforts have gone better?
Following news of the leak, plans were announced to burn some of the oil in order to contain the spill, but there was no fire boom on hand in order to facilitate that burn, despite a 1994 response plan that suggested their immediate use in the case of a major Gulf oil spill, according to The Press-Register in Mobile, Ala.
Other cleanup and containment efforts include skimming oil off the surface and using miles of protective booms to contain the oil's movement toward the coast.
BP has also bought up much of the world's supply of dispersants to use on the spill. Dispersants are chemicals intended to break up the oil. As we've reported, those chemicals could present their own environmental concerns, since their exact makeup is kept secret.
What was the White House's initial response?
The Obama administration says it has been fully engaged since "day one," but NPR reports that it was only after the rig sank two days after the explosion that the White House stepped up its involvement. At the time, President Barack Obama was assured that no oil was leaking from the ruptured well, and he subsequently left for a short vacation, according to a helpful NPR timeline. A leak was noticed that weekend.
What kind of job were regulators doing leading up to this incident?
As we've noted, the Minerals Management Service—an agency within the Department of the Interior—has a rather mixed record. In 2008, the regulator was involved in a sex and drug scandal with oil and gas company representatives. Since then, the agency has also been criticized for understating the risks of oil spills in its plans to expand drilling off the coast of Alaska. A government investigation also concluded that an office at MMS withheld data on offshore drilling from environmental risk assessors in the agency.
The Washington Post also reported that when BP was seeking permission to drill with the Deepwater Horizon rig, MMS gave BP what is known as a "categorical exclusion"--meaning drilling plans would not be subjected to a detailed environmental analysis. Exemptions are given when the likelihood of a spill is seen to be low. Reuters reports that between 250 and 400 exploration programs in the Gulf have been granted these exclusions.
How much oil has spilled into the Gulf?
At this point it remains unclear how much oil is spilling or has spilled into the Gulf. Estimates have continually been revised -- first from no oil leaking (April 23) to 1,000 barrels leaking per day (April 24), then to 5,000 barrels a day (April 29).
On Tuesday in a closed-door meeting, a BP executive told members of Congress that the well's flow could conceivably get more than 10 times worse and release 60,000 barrels of crude per day, according to The New York Times. BP said Wednesday that it had been able to stop one of the three leaks, though that hasn't reduced the flow significantly.
Who's on the hook for what happened?
Several congressional hearings are scheduled for next week, at which executives from BP, Halliburton and Transocean have been asked to testify. Several lawmakers have also called for investigations into MMS and its responsibility in the Deepwater Horizon incident. Investigators are also raising questions about Cameron International, the company that made the failed blowout preventer.
While accepting that it has to pay for the cleanup, BP has been trying to distance itself from the spill and push at least some responsibility on Transocean. "It wasn't our accident," BP CEO Tony Hayward said on NBC's "Today" show last week.
What's this I hear about a cap on how much BP will have to pay?
Everyone seems to be in agreement about BP paying for the cleanup, according to Talking Points Memo. That will include paying back federal agencies for their help in cleanup operations.
But liability for damages is a separate issue, and at the moment, damages are capped at $75 million by a 1990 law, according to The New York Times. Lawmakers in both the House and the Senate have introduced legislation that would raise the cap on damages to $10 billion. Those lawmakers, with support from the White House, hope to apply the measure retroactively to BP.
BP's CEO has said that the company will honor "all legitimate claims for business interruption."
What's happening now?
Currently, BP's best hopes of stopping all flow include drilling a relief well and lowering a containment dome over the leak to capture the oil and funnel it to the surface. But results may not be immediate, since drilling the relief well will take 90 days at best, according to the Coast Guard.
According to BP's chief operating officer, Doug Suttles, these techniques have been used effectively in shallower waters, but never in waters so deep.
ProPublica is America's largest investigative newsroom. Sign up for our daily email here.