Underwater oil plumes
On May 13, Robert Bea, who serves on a National Academy of Engineering panel on oil pipeline safety, said, "There's an equal amount that could be subsurface too," and that the oil below the surface "is damn near impossible to track." Also on May 13, Garland Robinette from New Orleans reported on NBC News that tarballs about the size of softballs —12 inches (30 cm) circumference— were washing up on the shores of three Louisiana parishes and may be coming in from under the surface of the water.[90]
On May 15, researchers from the University of Southern Mississippi aboard the research vessel RV Pelican identified enormous oil plumes in the deep waters of the Gulf of Mexico, including one as large as 10 miles (16 km) long, 3 miles (4.8 km) wide and 300 feet (91 m) thick in spots. The shallowest oil plume the group detected was at about 2,300 feet (700 m), while the deepest was near the seafloor at about 4,200 feet (1,300 m). Other researchers from the University of Georgia have found that the oil may occupy multiple layers "three or four or five layers deep". They have not indicated what the percentage of hydrocarbon is present in these underwater plumes. The New York Times speculates that the undetermined amount of hydrocarbons in these underwater plumes may explain why satellite images of the ocean surface have calculated a flow rate of only 5,000 barrels (210,000 US gal) a day, whereas studies of video of the gushing oil well have variously calculated that it could be flowing at a rate of 25,000–80,000 barrels (1,100,000–3,400,000 USgal) a day.[6]
In an interview on May 19, marine biologist Rick Steiner said that the likelihood of extensive undersea plumes of oil droplets should have been anticipated from the moment the spill began, given that such an effect from deepwater blowouts had been predicted in the scientific literature for more than a decade and confirmed in a test off the coast of Norway, and he criticized NOAA for not setting up an extensive sampling program to map and characterize the plumes in the first days of the spill.[91]
According to BP, estimating the flow is very difficult as there is no metering of the flow underwater.[65] The company has refused to allow scientists to perform accurate, independent measurements of the flow.[6] In their permit filed with the Minerals Management Service, BP quotes a worst case daily discharge of 3,900 barrels (160,000 US gallons; 620,000 litres) per day.[72] Before Congress, BP revised their figure upwards to 60,000 barrels (2,500,000 US gallons; 9,500,000 litres) per day if the blowout preventer and other equipment restricting the current flow were removed.[73]National Public Radio and shown underwater footage of oil and gas gushing out of the broken pipe put the leak rate substantially higher.[74] Timothy Crone, an associate research scientist at the Lamont-Doherty Earth Observatory, used another well-accepted method to calculate fluid flows, estimating "at least 50,000 barrels (2,100,000 US gallons; 7,900,000 litres) a day" leaking from the well. Eugene Chaing, a professor of astrophysics at the University of California, Berkeley, correctly estimated the pipe's diameter at approximately 20 inches (51 centimetres). Using just pencil and paper, he arrived at a figure approximating Crone's findings, stating, "I would peg [the flow] at around 20,000 barrels (840,000 US gallons; 3,200,000 litres) to 100,000 barrels (4,200,000 US gallons; 16,000,000 litres) barrels per day." Chaing also claimed the earlier figure of 5,000 barrels (210,000 US gallons; 790,000 litres) barrels a day is "almost certainly incorrect. Neither Crone or Chaing have indicated whether this method of analysis has been verified to be accurate at a depth of 5000 feet. "[75] Unspecified sources contacted by
Steven Wereley, an associate professor at Purdue University used a computer analysis (particle image velocimetry) to arrive at a rate of 70,000 barrels (2,900,000 US gallons; 11,000,000 litres) per day (plus or minus 20%).[76][77] However, after watching newly released video, on May 19 he said, "I can't say how much in excess of that 70,000 this leak is, but I would use the word 'considerable'".[78] In Congressional testimony, Werely stated that oil is escaping at the rate of 95,000 barrels — 4 million gallons — a day, nearly 20 times greater than the 5,000 barrel a day estimate BP and government scientists have been citing.[79]
A U.S. congressional panel heard testimony from experts including Wereley, who stated that estimating the rate of flow "is not rocket science," adding, . "All outside estimates are considerably higher than BP's." BP Chief Operating Officer Doug Suttles said on Wednesday, May 19, 2010 that BP's 5,000-barrels-a-day estimate was "highly" uncertain.[80]. On May 20, BP tacitly admitted that its own internal estimates of the rate of the spill were greater than 5,000 barrels per day when it estimated that 5,000 barrels per day represented a subset of the larger amount actually coming out. BP stated the amount it was capturing that day at 5,000 barrels per day while adding that "We're not claiming that we stopped [all oil leakage] although that is our final objective. We're saying that this is what we're capturing now."[81]
On May 20, after telling BP they would host the live feed if the company itself could or would not, U.S. lawmakers started streaming live video of the Gulf oil spill from 5,000 feet below sea level.[82]
http://globalwarming.house.gov/spillcam/
Expansion predictions
Some unspecified scientists predict that the Gulf Stream could pick up the oil and carry it around Florida to the East Coast, but on May 5, Robert Weisberg of The University of South Florida said winds would take the oil away from the Loop Current, which becomes the Gulf Stream. Ruoying He of North Carolina State University, head of the Ocean Observing and Monitoring Group, said if the oil reached the Gulf Stream, then south Florida, including the Keys, would likely be affected. Whether it comes ashore farther north depends on local winds, but the Gulf Stream moves away from the coast southeast of Charleston, South Carolina, at a formation called the Charleston Bump. Susan Lozier of Duke University said in late spring off the Carolinas, the winds would blow away from the shore. Rich Luettich, director of the University of North Carolina Institute of Marine Sciences in Morehead City, said the oil could remain a problem for as much as a year, or even longer. He did say in the unlikely event the oil reached North Carolina's coast, the Outer Banks would provide significant protection.[92]
On May 19, scientists monitoring the spill with the European Space Agency's Envisat radar satellite said that it has entered the Loop Current, which flows clockwise around the Gulf of Mexico towards Florida, and may reach Florida within 6 days. The scientists warn that because the Loop Current is a very intense, deep ocean current, its turbulent waters will accelerate the mixing of the oil and water in the coming days. "This might remove the oil film on the surface and prevent us from tracking it with satellites, but the pollution is likely to affect the coral reef marine ecosystem".[93]
NOAA acknowledged, on May 19, that "a small portion of the oil slick has reached the Loop Current in the form of light to very light sheens."[94]
Independent Monitoring and Testing for Extent of Contamination
Wildlife and environmental groups accused BP of holding back information about the extent and impact of the growing slick, and urged the White House a to order a more direct federal government role in the spill response. In prepared testimony for a congressional committee, National Wildlife Federation President Larry Schweiger said BP had failed to disclose results from its tests of chemical dispersants used on the spill, and that BP had tried to withhold video showing the true magnitude of the leak.
"The federal government should immediately take over all environmental monitoring, testing and public safety protection from BP," he said. "The Gulf of Mexico is a crime scene and the perpetrator cannot be left in charge of assessing the damage."[95]
On May 20, 2010 Interior Secretary Ken Salazar said that the U.S. government will verify how much oil has leaked into the Gulf of Mexico. "We're not depending on what BP is telling us," Salazar said.[96] On the same day, the heads of the U.S. Environmental Protection Agency and the Department of Homeland Security told BP chief executive Tony Hayward in a letter that the company had "fallen short" of its promises to keep the public and the federal government informed about the spill, writing that "BP must make publicly available any data and other information related to the Deepwater Horizon oil spill that you have collected." EPA Administrator Lisa P. Jackson and Homeland Security Secretary Janet Napolitano asked for the results of tests looking for traces of oil and dispersant chemicals in the waters of the gulf. BP did not respond Thursday to requests for comment about the letter, the Washington Post reported in a s story titled, "Estimated rate of oil spill no longer holds up."[97] Reuters quoted the letter as also stating ""In responding to this oil spill, it is critical that all actions be conducted in a transparent manner, with all data and information related to the spill readily available to the United States government and the American people..those efforts, to date, have fallen short in both their scope and effectiveness."[98]
The response in pictures
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Activities to stop the oil leak
The rig's blowout preventer (BOP), a fail-safe device fitted at source of the well, did not automatically cut-off the oil flow as intended when the explosion occurred. BP attempted to use remotely operated underwater vehicles (ROVs) to close the blowout preventer valves on the well head 5,000 feet (1,500 m) below sea level, a valve closing procedure taking 24–36 hours.[83][99] BP engineers predicted it would take six attempts to close the valves.[100] As of May 2, 2010, they had sent six ROVs to close the blowout preventer valves, but all attempts were ultimately unsuccessful.[101]
Oil was known to be leaking into the gulf from three different locations. On May 5, BP announced that the smallest of three known leaks had been capped. This did not reduce the spread of oil into the Gulf, but it did allow the repair group to focus their efforts on the two remaining leaks.[102]
Gulf oil spill: Smallest leak sealed off
The smallest of the three oil leaks on the floor of the Gulf of Mexico has been sealed off by robot submarines -- a move that doesn't reduce the amount of oil spilling out, but one that should make the overall effort to plug the leak less difficult, a U.S. Coast Guard official said.
The small leak -- the one furthest from the well head --was sealed off with a valve sometime between 6 p.m. CDT Tuesday and 6 a.m. Wednesday morning, U.S. Coast Guard Petty Officer Brandon Blackwell said.
But the two more substantial leaks, which are farther down a collapsed riser, or pipe, that had originally connected the wellhead with the drilling rig, continue to gush oil, and the overall rate of the spill is likely the same. "It's kind of like a garden hose with three leaks in it -- you cut off this leak but you still have two more," Blackwell said. http://latimesblogs.latimes.com/greenspace/2010/05/gulf-oil-spill-smallest-leak-sealed-off-.html
Short-term efforts
BP engineers have attempted a number of techniques to control or stop the oil spill. The first and fastest was to place a subsea oil recovery system over the well head. This involved placing a 125-tonne (280,000 lb) container dome over the largest of the well leaks and piping it to a storage vessel on the surface.[103] This option would have collected as much as 85% of the leaking oil but was an option that was untested at such depths.[103] BP deployed the system on May 7–8 but it failed when gas leaking from the pipe combined with cold water to form methane hydrate crystals that blocked up the steel canopy at the top of the dome.[104] The excess buoyancy of the crystals clogged the opening at the top of the dome where the riser was to be connected.
Following the failure of the 125-tonne (280,000 lb) containment dome, a smaller containment dome, dubbed a "top hat", was lowered to the seabed.[105] The dome was lowered on May 11 but is currently being kept away from the leaking oil well.[105] The dome is meant to funnel some of the escaping oil to a waiting tanker on the surface. Like the past containment dome, they have been used to tackle well and pipeline leaks in the past but not at such a depth.[105] At 4 feet (1.2 m) in diameter and 5 feet (1.5 m) in height, it is much smaller than the first 40 feet (12 m) 125-tonne (280,000 lb) dome.[105] The "top hat" dome will be deployed in the event that BP fails to control the spill by inserting a six-inch wide tube inside the leaking pipe.[104]
On May 14, engineers began the process of positioning a tube at the largest oil leak site.[104] Engineers attempted to insert a 6 inches (15 cm) wide tube into a jagged 21 inches (53 cm) pipe that is leaking oil onto the Gulf seabed. BP crews tried to insert the tube, which is surrounded by a rubber seal and attached to a tanker at the surface.[104] The tube would be inserted into the larger of two leaks, the one releasing about 85 percent of the crude oil.[104] A BP spokesman said it should be operational within the next several days.[104] However, initial attempts to insert the pipe failed, and BP said it would try again the following day.[106]
After three days, BP reported the tube was working.[107] On May 17, BP announced it was funneling approximately 1,000 barrels (42,000 US gallons; 160,000 litres) a day to a waiting tanker ship.[108] On May 18, BP said that they had increased the rate to 2,000 barrels a day[109], however newly released video shows the insertion tube with huge quantities of oil gushing past the device, and a second video shows views of the leaks at the blowout preventer with multiple streams of oil gushing from that area as well.[110] On May 19, BP announced that they were recovering about 3,000 barrels per day, more than half their estimate of 5,000 barrels leaking per day, but only 3% of the maximum estimate of 100,000 barrels leaking per day.[111]
BP likely will try to shut down the well completely late this week using a technique called “top kill,” BP Chief Operating Officer Doug Suttles said at a news conference on 17 May. The process involves pumping heavy drilling fluids through two 3-inch lines into the blowout preventer that sits on top of the wellhead. This would first restrict the flow of oil from the well, which then could be sealed permanently with cement.[112]
BP is siphoning up to 1,000 barrels of oil a day from the undersea leak in the Gulf of Mexico and hopes to double that while workers close in on another attempt to shut down the well for good.
A flexible tube inserted into one section of leaking pipe on Sunday is drawing about 20 percent of the estimated 5,000 barrels per day of oil pouring from the well 40 miles from the mouth of the Mississippi River. A barrel is 42 gallons.
The well has been leaking since April 20, when a blowout in BP's Macondo well destroyed the drilling rig Deepwater Horizon, killed 11 crew members and triggered the spill threatening the Gulf Coast.
A relief well aimed at intercepting the bottom of the leaking one in order to flood it with cement is about halfway complete, and drilling began Sunday on a second relief well. The well taps a formation more than two miles below the wellhead.
The relief wells will take at least another couple of months, and in the meantime BP likely will try to shut down the well completely late this week using a technique called “top kill,” BP Chief Operating Officer Doug Suttles said at a news conference Monday.
The process involves pumping heavy drilling fluids through two 3-inch lines into the blowout preventer that sits on top of the Macondo wellhead a mile underwater. This would first restrict the flow of oil from the well, which then could be sealed permanently with cement.
The blowout preventer is a massive array of valves and other cutoff devices that BP says failed to provide the intended last line of defense when well pressure surged April 20.
Suttles said the company was able to get pressure readings from the blowout preventer last week that indicate the well pressure is lower than expected and dropping, encouraging officials' belief that a top kill can work without making the problem worse.
“That's given us the confidence to move forward with this process,” Suttles said. “If successful, we would be bringing this incident to a close.”
A successful top kill would eliminate the need to try plugging the blowout preventer with rubber, knotted ropes and other material in a process called a “junk shot.”
Over the weekend the company resumed the use of oil dispersants underwater near the source of the spill, a new technique that was tested just a few times earlier this month and got the go-ahead from environmental regulators after an expedited review.
“We know there are concerns with the use of dispersants, and we just want to emphasize that this was not done lightly,” Coast Guard Rear Adm. Mary Landry said. “Everything we're doing in this case has tradeoffs.”
Charlie Henry, a scientific support coordinator with the National Oceanic and Atmospheric Administration, said studies of the dispersants and the overall spill are ongoing and will continue after the leak is stopped.
Landry and Suttles were optimistic about spill cleanup efforts this week as offshore winds and high volumes of water from the Mississippi River continue to push the oil spill out to sea.
The oil has not reached the Gulf's Loop Currents, which could carry it closer to Florida, Landry said, and shoreline effects so far have been “minimal.”
NOAA Administrator Jane Lubchenco downplayed a report over the weekend about undersea plumes of oil that appear to be emanating from the spill site, calling it “misleading, premature and, in some cases, inaccurate.”
The story said researchers found several large clouds of oil under the Gulf's surface with lower oxygen levels than normal, which could threaten ocean life.
Lubchenco said in a statement that below-normal oxygen levels were discovered, but “they are not low enough to be a source of concern at this time” and the NOAA-funded research hasn't reached definitive conclusions.
BP declined to comment on a report Sunday on CBS' 60 Minutes that the blowout preventer may have been damaged in an accident four weeks prior to the April 20 explosion on the rig and that BP overruled the drilling operator on key operations.
BP leased the rig from Transocean, which owned and operated it.
“There are multiple investigations ongoing and starting — including our own — and these will gather all the evidence in detail,” BP spokesman David Nicholson said. “But until their conclusion, we feel it would be premature to speculate on the detailed causes.”
BP said Monday it is providing $70 million in grants to the governors of Louisiana, Mississippi, Alabama and Florida to help those states promote tourism and help offset the impact of the spill.
“We understand the governors' concerns for the impact on the tourism industry and are making funds available so that they can support the industry's efforts to provide accurate information about the state of the beaches across the region,” BP CEO Tony Hayward said in a statement.
The grants are in addition to the four $25 million grants BP announced May 5 to help those states with spill response.
http://latimesblogs.latimes.com/greenspace/2010/05/gulf-oil-spill-smallest-leak-sealed-off-.html
Long-term efforts
BP is also preparing to drill a relief well into the original well to relieve it. Transocean's Development Driller III has started drilling a relief well on May 2, 2010.[113] Transocean's Discoverer Enterprise is also underway, should a second relief well be necessary. This operation will take two to three months to stop the flow of oil and will cost about US$100 million.[114] Re-drilling the well straight down was done in Australia after the 2009 Montara oil spill. In this case, once the second drilling operation reached the original borehole the operators pumped drilling mud into the well to stop the flow of oil.[115][116]
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