| http://www.washingtonpost.com/wp-dyn/content/article/2010/06/10/AR2010061003683.html?hpid=topnews Study: Well most likely spewing more than 1M gallons of oil a day By Joel Achenbach, Juliet Eilperin and David Fahrenthold Washington Post Staff Writer Thursday, June 10, 2010; 3:57 PM The Deepwater Horizon well has most likely spewed 25,000 to 30,000 barrels of oil a day, more than previously estimated, according to a group of scientists appointed by the federal government to study video of the dark geyser at the bottom of the Gulf of Mexico. The new estimate suggests that, if the flow has been more or less consistent since the April 20 blowout, approximately 1.3 million to 1.5 million barrels, or 53.6 million to 64.3 million gallons, of oil have emerged from the well. That is roughly five to six times the amount spilled in Alaskan waters in 1989 by the Exxon Valdez. Much of the oil flowing into the gulf has been skimmed, burned, or dispersed with chemicals, and the well is now capped and partially contained, with 15,800 barrels siphoned to a ship at the surface on Wednesday. But the new figures, obtained Thursday by The Washington Post and soon to be officially announced by the U.S. Geological Survey, indicate that early estimates of the flow rate by the federal government and oil giant BP were not even close to the mark. Last month, with the government sticking to an estimate of 5,000 barrels a day, and independent scientists arguing that the amount had to be much higher, national incident commander Adm. Thad Allen appointed the Flow Rate Technical Group to come up with a better estimate. The group, comprised largely of scientists in academia, had several subgroups, including one that looked at satellite imagery of the spill, and one, the "plume team," which examined low-quality video of the leaks from the damaged riser pipe. The group's May 27 report cited the best estimate for the flow at 12,000 to 19,000 barrels, but the plume team had a broader range in its own estimate, saying that the flow was "at least" 12,000 to 25,000 barrels a day and adding that it could be "considerably larger if the conservative numbers used to make the estimate were relaxed." "Our best estimate was 12 to 25, but we realized we could be wrong. We knew it couldn't be lower but it could be higher," said plume team member James Riley, a professor of mechanical engineering at the University of Washington. Since then the team members examined more low-quality video of the leaking riser. The video was taken prior to last week's shearing of the riser, which reduced the multiple leaks to a single, coherent plume that was soon capped. The extra scrutiny enabled the scientists to come up with their more precise estimate of 25,000 to 30,000 barrels, adding that it "could be as low as 20,000 barrels per day or as high as 40,000 barrels a day." But more numbers are coming. The plume team and other members of the flow rate group are preparing another estimate, this one based in part on high-definition video taken by submersibles after the riser was cut and provided to the scientists on Tuesday. That estimate could be released any day, and might nudge the official estimated flow still higher. The government had said that the cutting of the riser might increase the flow by up to 20 percent, because the kinked pipe would no longer be inhibiting the well. The flow rate is significant on several fronts. First, it gives the government and BP a sense of how much capacity they'll need among surface ships to handle all the oil gushing out the well and up a pipe to the Enterprise drillship, which is capable of processing only about 18,000 barrels a day. Other ships are being added to the effort. The site above the blown out well has become crowded with 25 to 30 different vessels at any given time, Allen said Thursday. Second, the fines that BP faces for polluting the gulf will be tied to how many barrels of oil have leaked. Third, the higher figures call into question the circumstances that led to the much lower estimates of the spill earlier in the crisis. On April 28, after having received estimates of the size of the spill from both BP and the National Oceanographic and Atmospheric Administration, the Coast Guard announced that the well was leaking about 5,000 barrels a day. That remained the official estimate for weeks. Allen rejected the suggestion this week that the government has been lowballing the flow rate. "I can guarantee you unequivocally, nobody is lowballing anything that works for me," he told reporters. "And I will never lowball anything. We will give you the honest data that we've got, and what -- the basis for the assumptions and where that led us." An internal BP document marked "confidential" shows that BP on April 27 had arrived at three different estimates for the size of the spill: low, best guess and high. The calculations were based on satellite imagery of the oil slick. The low estimate was 1,063 barrels a day. The best guess was 5,758 barrels. The high estimate was 14,266 barrels. The next day the Coast Guard announced the 5,000 barrel estimate. Oceanographer Ian MacDonald of Florida State University, who early in the crisis announced his own estimate of 26,500 barrels a day, said the confidential BP document reveals that the company made basic errors in calculating the thickness of the oil at the surface. "BP screwed up a fundamental engineering calculation, and as a consequence they had some bad numbers out there, and they gave these numbers to the Coast Guard," MacDonald said. "They underestimated the size of the slick on the surface and they neglected to account for the oil that was being lost in the midwater." BP spokesman Andrew Gowers said Thursday by e-mail, "There is no secret about this. It was our contribution to the Unified Command estimate that was published shortly afterwards. We have always said we made a contribution to that estimate but that it was an estimate by the Unified Command." The plume team estimate is still considered preliminary. The team's method tracks individual billows and estimates how far they traveled over a very short period, such as one-twentieth of a second. The speed of the features does not reveal, however, precisely how fast the oil inside the plume and out of sight is moving. Peter Cornillon, of the University of Rhode Island, said his group came up with a lower bound for their estimate -- 12,000 to 25,000 barrels a day -- but couldn't agree on an upper bound. "We never came up with a number on the upper end," Cornillon said. "If we came up with an upper bound, it would have to be quite large . . . The concern was that the press would focus on the upper bound." Once the riser was cut, said Steve Wereley at Purdue University, "The flow must go up," because the oil is no longer held up by the kink in the pipe. But Wereley said the flow was so poorly understood that he didn't believe estimates that the flow had increased by 20 percent. "I would be suspicious of that 20 percent number. I would be suspicious of any number, from anybody else, that does not have some sort of supporting documentation," Wereley said. |