BP reports 'static kill' success; scientists say majority of oil has been dispersed, removed

By William Branigin and David A. Fahrenthold
Washington Post Staff Writer
Wednesday, August 4, 2010; 3:54 PM

A procedure to pump heavy mud into the blown-out BP oil well in the Gulf of Mexico has succeeded in plugging it, officials said Wednesday, and government scientists reported that most of the crude that gushed from it for three months has dissipated or been removed from the water.

President Obama cautioned that much recovery work remains, and other officials warned that the threat from the damaged Macondo well will not be eliminated until it is "killed" later this month with a relief well. Moreover, federal officials said, the long-term effects of the oil spill, the worst in the nation's history, remain to be determined.

But in view of a series of early setbacks in efforts to control the blown-out well, BP's announcement early Wednesday that it had reached a "static condition" came as a huge relief. The term meant that pressure inside the well was brought under control through a mud-pumping process that began Tuesday afternoon.

(Read an analysis here of whether the well is really dead.)

BP called the achievement "a significant milestone" and said it stopped pumping mud into the Macondo well after about eight hours because the effort had been successful.

"The well is now being monitored, per the agreed procedure, to ensure it remains static," the company said in a statement. "Further pumping of mud may or may not be required depending on results observed during monitoring."

In a speech in Washington, Obama called the development welcome news. He also pointed to the report released Wednesday by government scientists who found that an estimated 74 percent of the oil has been recovered, burned, dispersed, evaporated, consumed by microbes or otherwise removed from the gulf.

"The long battle to stop the leak and contain the oil is finally close to coming to an end, and we are very pleased with that," Obama said at a meeting of the AFL-CIO Executive Council.

Obama added: "Our recovery efforts, though, will continue. We have to reverse the damage that's been done. We will continue to work to hold polluters accountable for the destruction they've caused. We've got to make sure that folks who were harmed are reimbursed, and we're going to stand by the people of the region for however long it takes until they're back on their feet."

As they huddled in BP's operations center, federal officials tried to manage expectations, saying that even if the operation known as "static kill" went as hoped, the well at the bottom of the Gulf of Mexico would not be finally plugged until it was intercepted and cemented by a relief well that crews have been drilling for three months.

The federal official in charge of the oil spill response, retired Coast Guard Adm. Thad W. Allen, told a New Orleans television station Wednesday that pumping mud into the blown-out well took care of the immediate threat but that the "bottom kill" technique involving the 18,000-foot relief well would still go ahead.

"We've pretty much made this well not a threat, but we need to finish this from the bottom," Allen told WWL-TV.

In a summary of the report from the National Oceanic and Atmospheric Administration, the White House said a third of the oil released in the spill was "captured or mitigated" by recovery operations, "including burning, skimming, chemical dispersion and direct recovery from the wellhead." It said 25 percent "naturally evaporated or dissolved, and 16 percent was dispersed naturally into microscopic droplets."

The summary said the "residual amount" of 26 percent "is either on or just below the surface as residue and weathered tarballs, has washed ashore or been collected from the shore, or is buried in sand and sediments." It said dispersed and residual oil eventually breaks down through natural processes and that "early indications are that the oil is degrading quickly."

Elaborating later in a White House news briefing, NOAA head Jane Lubchenco said "there is virtually no threat to the [Florida] keys or the East Coast," as had once been feared.

As for the residual oil, however, "no one is saying that it's not a threat anymore," she said. "We do remain concerned and are actively studying the overall impact that both the oil at the surface and the oil subsurface have had on the entire ecosystem of the gulf."

Lubchenco said that even though some of the residual oil is in microscopic parts per million below the gulf's surface, "dilute and out of sight doesn't necessarily mean benign." She added that "the consequences to shrimpers and to fishermen remain to be calculated."

At this point, said Steve Murawski, a senior scientist with NOAA, researchers are focusing on the damage the oil caused over the last three months, especially to sensitive larvae and small creatures living in the gulf.

This accounting shows "where the oil is," he said. "But you know, what did the oil do when it was there?" Because of this uncertainty, he would not say that Obama was wrong to label the BP oil spill the "worst environmental disaster" in U.S. history.

"I think it's too early to conclude it wasn't," Murawski said.

(Read NOAA's report here.)

Murawski said the 74 percent figure is based in large part on experiments in laboratories and on calculations using assumption about what the oil is doing. Much of it involves oil hidden in the deep waters of the gulf, where it is difficult to measure.

"I would say that those are the best estimates available to date. They are imprecise, because of the scale that we're dealing with," Murawski said in a telephone interview. "I think the point is the majority of the oil is accounted for [now]."

In all, scientists estimated this week, 4.9 million barrels (205.8 million gallons) escaped from the well. Since it was finally capped July 15, the government has sought to compile what it calls an oil "budget," in essence an accounting of where the oil went.

Murawski said the easiest part to account for was the roughly 800,000 barrels that was sucked out of the well to ships on the surface and never escaped into the water. That accounts for about 17 percent of the total spill.

Other fractions, relatively small, were taken care of by the vast cleanup effort mounted by the federal government and BP. Murawski said 5 percent of the oil was burned and about 3 percent was skimmed off the surface.

A far larger fraction, about 25 percent, was estimated to have evaporated off the gulf's waters. Murawski said that was based on established scientific calculations.

The most controversial part of NOAA's "oil budget" is likely to be its accounting of what happened to oil beneath the surface. The scientists estimated that 8 percent of the oil was hit with chemical dispersants and is now fully or partially broken down by underwater microbes. Another 16 percent was dispersed "naturally," by the force of the gushing well, and is also being broken down.

Murawski said these estimates were based on samples of the microbes taken in the spill: they seemed to be 50 to 1,000 times higher than normal. Other scientists had feared that these hyperactive microbes might cause their own problems by depleting underwater oxygen, but Murawski said no such problems have been noticed so far.

The remaining 26 percent of the oil, if the government's figures are right, would amount to about 1.3 million barrels (54.6 million gallons), which would be nearly five times the volume of the Exxon Valdez spill in 1989. Murawski said NOAA's testing so far has not found high levels of oil floating miles away from the wellhead. Even where concentrations of oil are highest, he said, the water still looks clear.

Still, Murawski said, he disagrees with the notion that this remaining oil no longer poses an environmental threat. "We don't know that," he said.

According to the most recent estimates of the oil that has spilled into the gulf since the April 20 explosion of the Deepwater Horizon drilling rig, the disaster is the largest unintentional oil spill in history.

© 2010 The Washington Post Company