Work continues to contain oil spill after rig fire in gulf

May 3, 2010
BP PLC and Transocean Ltd. worked to contain an oil spill from the Macondo exploration well off Louisiana following an Apr. 20 explosion, fire, and subsequent collapse of Transocean's Deepwater Horizon semisubmersible rig (OGJ Online, Apr. 21, 2010).

BP PLC and Transocean Ltd. worked to contain an oil spill from the Macondo exploration well off Louisiana following an Apr. 20 explosion, fire, and subsequent collapse of Transocean's Deepwater Horizon semisubmersible rig (OGJ Online, Apr. 21, 2010).

The incident left 11 missing and presumed dead, authorities said after ending an extensive air and surface search covering 5,375 sq miles.

Another 115 people evacuated the rig to nearby supply vessels, and 17 of those people were injured. Of the 11 missing, 9 worked for Transocean and 2 worked for M-I SWACO.

The Deepwater Horizon semi had been drilling the Macondo well for BP Exploration & Production Inc. about 52 miles southeast of Venice, La., in 4,992 ft of water on Mississippi Canyon Block 252 near Rigel gas field.

US Coast Guard vessels fire water cannons at the Deepwater Horizon semi to try and extinguish a fire that engulfed the rig. Photo from US Coast Guard.

The well struck oil and associated gas at more than 18,000 ft TD. Crews were running casing and cementing operations before the explosion and fire, Transocean and BP spokesmen said. Cause of the accident remains under investigation.

On Apr. 22, the Deepwater Horizon rig sank and now rests on the ocean floor about 1,300 ft from the wellhead. Response officials estimated that a total of 1,000 b/d of oil was being released from two places with most of the oil coming from the end of the drill pipe (OGJ Online, Apr. 26, 2010).

Oil also leaked from the riser about 5 ft from the wellhead. Another 700,000 gal of diesel fuel remained contained within tanks aboard the rig.

Spilled oil spread to a 600-mile circumference rainbow sheen with areas of emulsified crude oil 36 miles off Louisiana, US Coast Guard officials said (OGJ Online, Apr. 27, 2010).

As OGJ went to press last week, officials said the leading edge of the spill was 20 miles from the coast. A controlled burn was being considered.

USCG Rear Adm. Mary Landry said the burn, if done, would not be seen from shore, and air quality would be monitored. She noted that such a burn would be smaller and less hot than the original rig explosion and fire had been.

Meanwhile, three members of the US Senate requested a joint hearing of the Senate Commerce and Energy committees on offshore oil and gas safety oversight.

Containment efforts

"We are attacking this spill on two fronts—at the wellhead and on the surface offshore," said BP Group Chief Executive Tony Hayward, who met with response personnel in Louisiana.

Doug Suttles, BP's chief operating officer of exploration and production, said the initial main effort was to stop the oil flow through the blowout preventer (BOP) using four remotely operated vehicles.

"We're trying to activate the blowout preventer from the outside," he said. Response teams were uncertain of conditions within the BOP.

The oil response team used more than 29,280 ft of boom to contain the spill on the ocean's surface. This involved about 50 vessels, including skimmers, tugs, and barges. Photo from US Coast Guard.

"I don't believe any of us understand why this event occurred," Suttles said. "We don't know at this time what the blowout preventer did" at the time of the accident.

A second plan was to drill one or two relief wells as needed. MMS had studied the strategy and was prepared to grant permits for relief wells, said Lars Herbst, Gulf of Mexico regional director for the US Minerals Management Service. A third effort involves designing and building a subsea containment and collection system, Suttles said. Oil and gas would be moved by pipe from the seabed to the surface.

The blazing Deepwater Horizon semi listed and sank on Apr. 22, extinguishing the fire after an Apr. 20 explosion that left 11 crew members missing and injured another 17 workers. Photo from an anonymous source.

"We don't know which technique ultimately will be successful," Suttles told reporters during an Apr. 26 news conference.

If workers are unable to get the oil under control through the BOP, Suttles estimated it would take at least 2 weeks to complete the engineering and fabrication of the dome collection system.

"This hasn't been done in 5,000 ft of water before," Suttles said of the collection system.

A relief well or wells would intercept the existing wellbore close to the original well's 18,000 ft TD, he said.

The drilling rig Development Driller III was moved into position to drill a relief well to intercept the Macondo well and inject a specialized heavy fluid to prevent flow of oil and gas. A second drilling rig was expected to arrive in early May.

Dispersants were applied to the spill. A field operations response office was set up in Houma, La., and USCG reported more than 1,000 people worked on the response.

BP said operational and technical experts worked with several agencies, including USCG, MMS, Louisiana Department of Environmental Quality, National Oceanic and Atmospheric Administration, US Fish and Wildlife Service, Louisiana Wildlife and Fisheries, and the Marine Spill Response Corp. (MSRC).

Steve Benz, MSRC president and chief executive officer, said the response to stemming the oil flow was the "largest response effort in MSRC's 20-year history."

BP's Hayward said, "Given the current conditions and the massive size of our response, we are confident in our ability to tackle this spill offshore."

BP's Suttles noted Apr. 27 that an estimated $6 million/day was being spent for recovery efforts from the spill.

Congressional inquiry

Three members of the US Senate requested a joint hearing of the Senate Commerce and Energy committees on offshore oil and gas safety oversight. Sens. Bill Nelson (D-Fla.), Frank R. Lautenberg (D-NJ), and Robert Menendez (D-NJ) made their request in an Apr. 26 letter.

"The explosion, ensuring fire, and continuing spill raise serious concerns about the industry's claims that their operations and technology are safe enough to put rigs in areas that are environmentally sensitive or are critical to tourism or fishing industries," the senators said in the letter.

They noted that the Deepwater Horizon incident was "certainly not an isolated incident." The MMS reports 509 fires caused at least 2 fatalities and 12 serious injuries on rigs in the gulf since 2006.

State authorities in Louisiana, Alabama, Mississippi, and Florida are on standby with booms if needed to protect environmentally sensitive areas in case any oil reaches the coast (OGJ Online, Apr. 27, 2010).

Another drilling rig, the Ocean Endeavor owned by Diamond Offshore Drilling Inc., was evacuated as a precaution, said Herbst of the MMS. Ocean Endeavor is 10 miles northeast of Deepwater Horizon's original location.

Charlie Henry, a scientific support coordinator with NOAA, said three whales, believed to be sperm whales, were spotted near the sheen during an Apr. 26 flyover.

The use of dispersants was adjusted to avoid areas where the whales were seen.

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