BP Deepwater Horizon Oil Spill
Principles of Sustainability
BP Deepwater Horizon Oil Spill
The oil slick as seen from space by NASA's Terra satellite on 24 May 2010.
By NASA/GSFC, MODIS Rapid Response AND demis.nl AND FT2 [Public domain], via Wikimedia Commons.
SUMMARY
The Deepwater Horizon oil spill stemmed from an explosion and fire on British Petroleum’s Deepwater
Horizon drilling platform in the Gulf of Mexico on
April 10, 2010. The explosion claimed eleven lives
and triggered the largest accidental marine oil spill
in history until its capping on July 15, 2010. It was
also the largest oil spill of any kind in the United
States. The spill raised questions about the safety of
deepwater drilling, the adequacy of the corporate
response to the disaster and of governmental regulation of offshore oil drilling, and the possibility of
long-term damage to the Gulf of Mexico’s ecosystem.
FIELDS OF STUDY
Disasters; Ecology, Environment, Environmentalism;
Pollution, Emissions, Toxic Waste, Hazardous
Materials; Oceans, Seas, Lakes, Bodies of Water
The Deepwater Horizon was a semisubmersible drilling
platform owned by Transocean and under lease to
British Petroleum (BP). In April 2010, it was located
in the Gulf of Mexico approximately 84 kilometers
(52 miles) southeast of Venice, Louisiana, where it
was completing work on the exploratory Macondo
252 well. Oil had been found 5.5 kilometers (18,000
feet) below the seafloor and 7 kilometers (23,000
feet) below the drilling platform. The drill hole had
been—or was being—cemented to seal the well so
that the drill pipe could be removed and the Deepwater
Horizon could be moved to a new location. The cement failed, allowing gas and oil under high pressure
to escape the reservoir and rise through the drill pipe
casing and up the riser pipe to the drilling platform.
A blowout preventer located on top of the wellhead was designed to cut through the drill casing
and seal the wellhead in cased of an emergency.
The blowout preventer also failed, and about 11:00
pm Central Daylight Time on April 20, the escaping
gas reached the surface and exploded, setting the
Deepwater Horizon on fire. Most of the workers on the
platform were evacuated without serious injury, but
eleven who had been in close proximity to the explosion died and seventeen were injured.
Without any mechanism to stop the flow of oil to
the platform, fireboats were unable to extinguish
the flames. The drilling platform burned for about
thirty-six hours and then sank, twisting and breaking
the riser pipe that had connected the platform to the
wellhead some 1.5 kilometers (5,000 feet) beneath
the sea surface.
Magnitude of the Spill
On April 24, unmanned submarines working for BP
detected oil flow from the wellhead and the collapsed
riser pipe. The magnitude of the flow was estimated
to be about 1,000 barrels per day (BPD), a figure repeated by both company and governmental officials.
(One barrel of oil equals 42 gallons, or approximately
159 liters.) On April 26 a scientist with the National
Oceanic and Atmospheric Administration (NOAA)
estimated the flow at roughly 5,000 BPD based on
satellite imagery of the oil slick. Nongovernmental
scientists using similar methodologies provided estimates as high as 26,500 BPD.
After BP released video images of the underwater
leak on May 12, independent experts reported estimates of up to 50,000 BPD. Despite the existence
of potentially better methodologies, government officials adhered to their estimate of 5,000 BPD until
May 27, when a government task force, the Flow Rate
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46
Principles of Sustainability
Group (FRG), released its first estimate: 12,000 to
25,000 BPD. FRG estimates were increased to 20,000
to 40,000 BPD on June 12 and to 35,000 to 60,000
BPD on June 15. By that time oil was being washed up
on the shores of the coasts of Louisiana, Mississippi,
Alabama, and Florida.
In the aftermath of the spill, both government
and independent scientists appeared to agree that
the actual flow rate was approximately 60,000 BPD
and that the total release of oil into the Gulf was approximately 5 million barrels, roughly twenty times
the volume of the 1989 Exxon Valdez oil spill in Prince
William Sound. This was the largest oil spill in the
history of the Gulf of Mexico, exceeding the 3 million gallons discharged into the Gulf after the 1979
PEMEX oil spill off the coast of Mexico.
Emergency Response
Within one week of the initial explosion, oil had
reached the Mississippi Delta, and the nation became
aware that the Gulf oil spill threatened serious economic and environmental damage. The event was
better described as a discharge, a blowout, a flow, or
a leak, but the term “spill” was almost universally adopted. In the space of a few days, President Barack
Obama announced that the United States would use
all available resources to contain the spill. Fishing
was prohibited in the affected areas, and a moratorium was declared on further deepwater drilling in
the Gulf of Mexico pending an investigation. Obama
announced that British Petroleum was responsible
for the spill and that it would be held responsible for
the cleanup. The U.S. Coast Guard commandant,
Admiral Thad Allen, was named incident commander
for the federal response, and it was announced that
a national commission would be formed to study the
disaster and make recommendations. BP chief executive officer Tony Hayward declared that BP would
take full responsibility; he pledged to stop the leak,
repair the damage to the Gulf, and pay all legitimate
claims for damages.
From the beginning experts agreed that the permanent solution would be a relief well that would
intersect the drill hole below the lowest level of drill
pipe casing and above the top of the petroleum reservoir. Cement pumped through the relief well would
seal the reservoir permanently. BP began drilling
such a relief well on May 2. It was anticipated that
the relief well would be completed in August, but
BP Deepwater Horizon Oil Spill
waiting that long to stop the flow of oil was not a viable option.
BP pursued multiple strategies to stanch the flow.
Several attempted quick fixes were relatively unsuccessful. Remotely controlled underwater vehicles
working for the company failed to close valves on the
blowout preventer. Surface oil slicks were burned on
several occasions, but the volume of oil consumed
was relatively small. U.S. Air Force planes were enlisted to spray chemical dispersants on surface slicks
while BP injected dispersants underwater in an effort to break up the oil flow at the source. More than
1.8 million gallons of dispersants were used—almost
800,000 gallons near the wellhead.
Local fishing boats were hired to skim floating oil,
and miles of booms were deployed in an effort to prevent slicks from contaminating ecologically sensitive
coastlines. In many areas wind and waves rendered
these strategies ineffective. Efforts were also undertaken to construct artificial barrier islands to protect
fragile coastlines. Every strategy was controversial,
and some worked at cross-purposes. Some communities, for example, feeling that the response was too
slow, erected their own booms and barriers at the
mouth of rivers and bay inlets. Chemical dispersants
also made the use of booms and skimming less effective but also arguably less necessary. At the height of
the crisis thousands of people and hundreds of vessels were employed in efforts to mitigate the environmental damage of the spill.
By early May it was apparent that at least three significant leaks were coming from a section of broken
riser pipe that lay crumpled on the ocean floor still
attached to the failed blowout preventer on the wellhead. On May 4 remotely controlled underwater vehicles successfully sawed off the free end of the leaking
riser pipe and installed a shutoff valve, reducing the
number of leaks to two, but without significantly diminishing the flow of oil. On May 7 and 8 one of three
custom-built coffer dams was lowered over the largest
leak on the ocean floor. This concrete and metal box,
12 meters (40 feet) high, was designed to capture the
plume of escaping oil so that it could be pumped to
the surface. The coffer dam failed, however, when a
frozen mixture of gas and water clogged the system.
A smaller version, dubbed “top hat,” was lowered on
May 11 but never deployed. Instead, BP chose to insert a 15.2-centimeter (6-inch) pipe directly into the
leaking 53.3-centimeter (21-inch) riser pipe.
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BP Deepwater Horizon Oil Spill
On May 16 BP announced that it was capturing
most of the leaking oil, but the following day the
estimate of oil captured was reduced to 1,000 BPD,
approximately one-fifth of BP’s estimated leak rate.
Plans were announced for a “junk shot” to plug the
leak by injecting the well with a high-pressure mixture of cement and solids such as shredded tires. It
was never executed, however; instead BP chose the
“top kill,” which was designed to stop the flow by
pumping drilling mud into the blowout preventer.
This procedure failed to stop the flow, even after
“junk shot” solids were added to the mixture.
By June 1, BP was working to saw off the broken
riser pipe just above the blowout preventer and attach a cap connected to a new riser pipe. This strategy
entailed significant risk because cutting off the bent
riser pipe would increase the flow of oil into the Gulf.
The cap was connected, but the fit was loose. Over
time the fraction of escaping oil that was recovered
slowly increased, approaching 50 percent. A significant fraction of the captured oil was burned at the
surface. After about a month, while efforts continued
to drill relief wells, BP removed the cap and replaced
it with what amounted to a blowout preventer on top
of the previous blowout preventer. After eighty-seven
days, the flow of oil was stopped on July 15.
In August, as work on the relief wells continued,
BP announced a successful “static kill.” Tons of
drilling mud followed by cement were pumped into
the wellhead, providing increased assurance that
the flow would not resume. The first relief well intersected Macondo 252 on September 16, and crews
cemented the blown-out well from the bottom. The
federal incident commander declared Macondo 252
officially sealed on September 19.
Consequences
The economic damages associated with the BP oil
spill were dire. One study estimated just the shortterm damage to the Gulf fishing industry at $115 to
$172 million. Severe economic impacts were also associated with the deepwater drilling moratorium and
the spill’s damage to the “Louisiana brand.” Perhaps
the clearest economic indicator of damage done was
reduced investor confidence in BP. Between April 21
and June 25, 2010, the value of BP stock declined by
55 percent, representing a reduction of $67 billion in
market capitalization. By the time the well was sealed,
BP had reportedly spent more than $11 billion on the
Principles of Sustainability
capping and cleanup operations, and it had created a
$20 billion escrow account for payment of damages,
which was depleted by 2013. In the autumn of 2010,
BP announced that it had taken a pretax charge of
$32.2 billion and had plans to sell up to $30 billion in
assets. It had canceled its stock dividend.
In 2012, BP signed a settlement agreement to
compensate businesses that suffered financial losses
due to the spill. BP later attempted to challenge this
settlement agreement in court, although the U.S.
Supreme Court rejected the challenge in December
2014. Also in 2012, BP reached an agreement with
the U.S. Department of Justice, in which the company pleaded guilty to fourteen criminal charges,
including violations of the Clean Water Act and the
Migratory Bird Treaty Act, which carried more than
$4.5 billion in penalties and fines. In November
2012, the U.S. Environmental Protection Agency
(EPA) suspended BP from entering into any new
federal contracts, a ban that lasted until March 2014.
In April 2016, courts approved a settlement with BP
for natural-resource damages caused by the spill, allocating up to $8.8 billion for the restoration of damaged wildlife, habitats, and ecosystems.
BP’s long-term liability will depend in part on the
environmental and medical damage caused by the
spill, which may be even more difficult to measure
than economic damage. Studies are expected to continue for years if not decades. The fate of the spilled
oil remains the subject of scientific controversy. No
one knows with any degree of certainty what fraction evaporated, sank to the bottom of the Gulf, or
remained suspended in the water column. The environmental consequences of the unprecedented intensive use of chemical dispersants remain unclear,
but preliminary analyses by the EPA indicated that
the environmental benefits of dispersant use outweighed the environmental cost. By 2015, five years
after the spill, U.S. Fish and Wildlife officials reported
that almost 30 percent fewer shrimp and crabs were
being harvested from the northern Gulf than before
the spill. Although the demand for Gulf Coast seafood had rebounded by this time, the subsequent reductions in catch have not yet been specifically tied
to reduced crustacean populations as a result of the
Deepwater Horizon oil spill.
The totality of environmental damage to the Gulf
of Mexico from the Deepwater Horizon spill will certainly be significant, but the ecological significance
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BP Deepwater Horizon Oil Spill
Principles of Sustainability
of a major oil spill may depend significantly on the
location. The ecological damage done by the Exxon
Valdez grounding in Prince William Sound was disproportionate to the size of the spill. By contrast,
the vastly larger PEMEX spill in the Gulf of Mexico
is generally regarded as having caused relatively little
environmental damage. Despite the attention given
to the acute BP spill, the chronic damage from agricultural runoff throughout the Mississippi River
basin probably remains the most significant ecological threat to the Gulf.
The BP oil spill raised important questions about
the safety of deepwater drilling, the industry’s preparedness for spills, and the government’s supervision of industry behavior. Early reports by the national commission studying the spill indicated that
the industry and the government were both poorly
prepared for a spill of such magnitude. BP and its
contractors had bypassed safety measures, and government agencies had routinely approved work that
did not meet legal standards.
—Craig W. Allin
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“Deepwater Horizon Oil Spill.” Office of Response
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Fingas, Mervin. The Basics of Oil Spill Cleanup. Boca
Raton: CRC Press, 2013.
Hurley, Lawrence. “U.S. Supreme Court Rejects BP
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Jernelöv, Arne. “The Threats from Oil Spills: Now,
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Sobecky, Patricia. Gulf of Mexico Microbial Cleanup: the
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COPYRIGHT 2017 Salem Press, a division of EBSCO Information Services, Inc., and Grey House Publishing, Inc.
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