Relief Well Was Used to Halt Australian Spill
By KEITH BRADSHER
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PTTEP
The Montara Spill Fire burned on a partially collapsed Montara wellhead in the Timor Sea in November 2009, just after a relief well halted an oil leak in the sea that had lasted for more than 10 weeks.
Multimedia
Related
BP Moves to Fix a Leak as Obama Warns of Damage (May 3, 2010)
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U.S. Coast Guard
The Gulf of Mexico Spill Response crews battled a fire on the Deepwater Horizon offshore oil rig in the Gulf of Mexico last month. The rig sank April 22. Eleven workers died and three were critically injured.
The New York Times
The gulf spill site, top, and the 2009 Timor Sea spill site.
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HONG KONG — While BP tries various short-term efforts to plug a leaking oil well in the Gulf of Mexico, the company is preparing to drill a relief well as a backup plan. BP hopes to drill that well diagonally to intersect the original one below the seabed and then flood it with mud and concrete to stop the uncontrolled flow.
Although the idea sounds simple, the experience with a similar spill last year near Australia shows just how difficult it can be to execute the maneuver.
“It’s like finding a needle in a haystack,” said Rachel Siewert, an Australian senator who is a member of the country’s opposition Greens Party and is critical of the oil industry.
The Australian accident, known as the Montara spill, began Aug. 21 with a blowout of high-pressure oil similar to the one in the gulf. With the well spewing 17,000 to 85,000 gallons per day, precious weeks passed before the relief wells were started. When efforts got under way, the first four attempts — drilled on Oct. 6, 13, 17 and 24 — missed the original well.
A fifth attempt finally intersected the original on Nov. 1, and about 3,400 barrels of heavy mud were pumped through the relief well into the base of the original well. The spewing oil finally stopped Nov. 3 — more than 10 weeks after the original explosion.
BP intends to drill a similar relief well close to the site where the Deepwater Horizon drilling rig blew up and sank in the gulf nearly two weeks ago. The company says the well could take months to complete. In the meantime, the well continues to leak 210,000 gallons of oil a day, according to the latest official estimates.
The Montara accident resembled the Gulf of Mexico accident in that both started with problems in the well itself, and it proved very hard to stop without resorting to further underground drilling, said Elmer P. Danenberger III, who was the top American regulator of offshore oil drilling until his retirement on Jan. 2.
“There are clearly some similarities,” Mr. Danenberger said.
Drilling the relief well proved tricky in the Montara spill, which was located in Australian waters in the Timor Sea, between northwest Australia and Indonesia.
The drilling team was trying to hit a well casing less than 10 inches in diameter at a depth 1.6 miles below the seabed, according to testimony this spring before an Australian government commission of inquiry.
The BP well has an even skinnier casing, reportedly measuring seven inches in diameter.
The companies involved in the Australian and American accidents are mostly different. In the Gulf of Mexico, BP, based in London, leased the drilling platform from Transocean, a Swiss company.
In the Timor case, it was PTT Exploration and Production, a Thai company, which had leased the West Atlas drilling rig and its crew from Atlas Drilling, an affiliate of Seadrill Management, a Norwegian company.
PTT’s and Seadrill’s offices were closed for the weekend and their officials could not be reached for comment. In documents submitted to the commission of inquiry, PTT acknowledged that it should have used more concrete for a temporary plug injected into the well when drilling was briefly halted before the blowout, but maintained that the basic design of the plug conformed to industry standards.
Atlas and PTT have disagreed in their submissions to the commission over whether PTT employees made an error in unscrewing a pressure-containing cap on top of the well shortly before the blowout.
Halliburton, a major oil services company based in Houston, was involved in the concrete work as a contractor in both the Montara and Gulf of Mexico spills.
A Halliburton employee, David A. Doeg, testified to the Australian commission that he made the problem worse at the Montara well by repumping concrete during an incorrectly handled procedure before the blowout. But Mr. Doeg testified that he was taking direction from PTT managers.
Halliburton’s role in the Gulf of Mexico disaster has also come under scrutiny. In a statement Friday, the company confirmed that it conducted concrete operations on the rig shortly before the accident but said it was “premature and irresponsible to speculate” on the cause. Halliburton said it was cooperating with investigations into the spill.
The Montara spill differed from the gulf spill in some ways that made it easier to stop, and in other ways that made it harder to stop. To begin with, the Montara drilling platform was operating in water that was 250 feet deep, while the Deepwater Horizon drilling rig leased by BP was on a seabed 5,000 feet deep.
But the seabed geology around the base of Deepwater Horizon has been well mapped, which would help any effort to drill a relief well there, Mr. Danenberger said. The Montara spill occurred during initial exploration of a seabed that is less well known.
BP is also pursuing other options, including continuing its efforts trying to activate a malfunctioning, 40-foot-tall blowout preventer on the ocean floor and trying to cover the undersea leak with a dome that would capture the oil so that it could be piped safely to the surface.
The Montara oil well had no blowout preventer on the sea floor.
The Montara oil spill last year was Australia’s third worst, after tanker spills in 1975 and 1991, and its worst from offshore oil production.
The Australian accident had a smaller environmental impact than the gulf spill is likely to have. In the Montara case, the oil spilled into the ocean far from land. Small quantities reportedly washed up in Indonesia, but most of it dispersed on the open ocean after forming a thin sheen covering up to 10,000 square miles.
The commission of inquiry into the Montara spill was originally scheduled to issue its report by Friday, but has delayed it to analyze the complex causes and effects of the spill. The Australian government is separately drafting legislation for tighter oversight of the offshore drilling industry.
Ms. Siewert said in a telephone interview this weekend that her party opposed any immediate move to change the rules for the industry. The Green Party believes that when the results of the commission’s inquiry are released, they should provide support for even tougher regulations than anything proposed so far, she said.
The Montara and Gulf of Mexico spills are not the only ones involving offshore drilling platforms. The Ixtoc oil platform in the Gulf of Mexico suffered a blowout in 1979 and leaked oil off the Mexican state of Campeche; some of the oil reached the Texas coast as well.
