Oil spills refer to the accidental or intentional discharges of raw or refined petroleum products on land or at sea (Prince 2010, p. 2617). The waters of oceans and restricted seas can be polluted by oil in several ways. Oil sources include natural seeps along the ocean floor, stream runoff from the land, wastewater drainage outlets from industrial complexes, offshore drilling accidents, deliberate purging of ballast or cargo areas of ships, and accidents involving oil supertankers. The petroleum input into the marine environment from ocean-derived factors has been estimated at about 56 percent. This calculation includes transportation losses during loading and unloading (30 percent), oil spills (5 percent), offshore production losses (1 percent), atmospheric pollution (10 percent), and offshore oil seeps (10 percent) (Prince 2010, p. 2617). What is evident is that oil spills pose both short- and long-term environmental threats, including injuries and deaths among fish, birds, and other wildlife; damage to shoreline recreational areas; and pollution of water supplies. While various oil spills have occurred since the inception of the petroleum industry, the Deepwater Horizon Oil Spill incident (Gulf of Mexico Oil Disaster) is considered the largest marine oil spill of all time (Prince 2010, p. 2618), and estimated at about 8% to 31% of the previous largest (Ixtoc I Oil Spill). The Deepwater Horizon Oil Spill began with an explosion on British Petroleum’s Deepwater Horizon drilling platform on 20th April 2010, which subsequently 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.
Purpose
Oil disasters cause a number of undesirable effects, especially on marine life. Oil spills affect the life of sea fish, plants, and birds; it damages water supplies, water transport, along with the appearance of beach recreational areas (Walker 2010, p. 49). Human health can also be adversely affected by oil spills. Cleanup workers, animal rescuers, and nearby residents who are exposed to the volatile organic compounds and other petroleum components may exhibit respiratory, gastric, and dermatological ailments in the near term. People living near an oil spill may also have difficulty getting adequate nutrition and water or otherwise maintaining their livelihoods as drinking water, game animals, fish, or surrounding croplands become contaminated (Walker 2010, p. 49). In this regard, the purpose is to study previous cases of oil spills so as to acquire lessons to prevent or adequately manage future possible incidents. With this, the explosion and fire on the Deepwater Horizon drilling platform in the Gulf of Mexico that claimed eleven lives and triggered the largest accidental marine oil spill in history and the largest oil spill of any kind in the United States is a suitable case for study.
Discussion
Overview of the Incident
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 (Walker 2010, p. 49). 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 (Walker 2010, p. 49). A blowout preventer located on top of the wellhead was designed to cut through the drill casing and seal the wellhead in case of an emergency. The blowout preventer also failed, and at about 11:00 p.m. central daylight time on April 20 the escaping gas reached the surface and exploded, setting the Deepwater Horizon on fire (Walker 2010, p. 49). 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 (Reddy et al. 2012, p. 20229).
Figure 1: Deepwater Horizon prior to explosion
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 (Reddy et al. 2012, p. 20230). 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 (Reddy et al. 2012, p. 20230; McNutt et al. 2012, p. 20260).
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 Group (FRG), released its first estimate: 12,000 to 25,000 BPD (Reddy et al. 2012, p. 20231). 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 (McNutt et al. 2012, p. 20261).
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 (McNutt et al. 2012, p. 20261). 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 (McNutt et al. 2012, p. 20261).
Figure 2: The Extent of the Deepwater Horizon Oil Spill, Mid-June, 2010
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 (Reddy et al. 2012, p. 20232). Fishing was prohibited in the affected areas, and a moratorium was declared on further deepwater drilling in the Gulf of Mexico pending an investigation. President Obama announced that British Petroleum was responsible for the spill and that it would be held responsible for the cleanup. The US 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 (Reddy et al. 2012, p. 20232); he pledged to stop the leak, repair the damage to the Gulf, and pay all legitimate claims for damages.
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. US 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 (Reddy et al. 2012, p. 20233). 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. Chemical dispersants, for example, 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.
Figure 3: A C-130 Hercules sprays Corexit dispersant onto the Gulf of Mexico
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 (Reddy et al. 2012, p. 20233). 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, 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 (Reddy et al. 2012, p. 20233).
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 (McNutt et al. 2012, p. 20263). 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 (McNutt et al. 2012, p. 20263).
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 (McNutt et al. 2012, p. 20264).
Effects
The economic damages associated with the BP oil spill were dire. One study estimated just the short-term damage to the Gulf fishing industry at $115 to $172 million (Jernelöv 2010, p. 355). 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 (Jernelöv 2010, p. 355). By the time the well was sealed, BP had reportedly spent more than $11 billion on the 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, and had canceled its stock dividend (Jernelöv 2010, p. 356).
Thousands of mammals, sea turtles, and birds were plastered with leaked oil, and many sea animals were found dead (Walker 2010, p. 50). Typical causes of such high mortality were suspected to be the contaminants from the spill that had made sea creatures vulnerable. Birds were the most affected, as many perished after ingesting oil in the attempt of cleaning themselves. A study in 2014 revealed that nearly 30 percent of laughing gulls and 12 percent of brown pelicans in the area hit by the spill had been wiped out (as cited in Fingas 2016, p. 186). The same study also indicated that over 800,000 birds had died.
Legal Aspects and Settlements
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 US Supreme Court rejected the challenge in December 2014 (Gill, Picou, " Ritchie 2012, p. 15). Also in 2012, BP reached an agreement with the US 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 US Environmental Protection Agency (EPA) suspended BP from entering into any new federal contracts, a ban that lasted until March 2014 (Gill et al. 2012, p. 15). 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 (Gill et al. 2012, p. 16).
Figure 4: Oil stained beaches in Pensacola, Florida, 1 July 2010
Conclusion
Spills of crude and fuel oils from tankers, freighters, pipelines, wells and storage facilities capture the public’s attention, and demand prompt and environmentally sensitive response technologies. The 2010 British Petroleum (BP) oil spill has illustrated the harm that oil leakages can cause to ocean-based ecosystems. 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. What is evident is that the totality of environmental damage to the Gulf of Mexico from the Deepwater Horizon spill will certainly be significant. 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, and 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. Besides, the environmental consequences of the unprecedented intensive use of chemical dispersants remain unclear.
Reference list
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