Oceans, caught between devil and the deep blue sea… (Pun intended!) – XVIII

Deepwater Horizon Oil Spill:

Deepwater Horizon.jpg

One of world’s worst and America’s most significant oil spills is known as Deepwater Horizon Spill.  The Deepwater Horizon oil spill is a maritime disaster that began on 20 April 2010, in the Gulf of Mexico (in the US), on the British Petroleum (BP), operated oil well Macondo Prospect.  On 20th April 2010, at an ultra-deep-sea well named Macondo Prospect, there was a blowout.  This blowout caused an explosion on the Deepwater Horizon offshore drilling rig.  BP had leased this drilling rig from Swiss drilling services contractor Transocean.  Two days after the explosion, the rig sank 5,000 feet to the ocean floor.  Macondo Prospect kept on spewing oil from the exploded well, until BP’s restoration team finally capped it on 19th September 2010, five months after the blowout.  

Deepwater Horizon Pic 1.jpg

Platform supply vessels battle the blazing remnants of the off shore oil rig Deepwater Horizon. A Coast Guard MH-65C dolphin rescue helicopter and crew document the fire, while searching for survivors. Multiple Coast Guard helicopters, planes and cutters responded to rescue of the crew. Photo by U.S. Coast Guard.

The U.S. government estimated that the disaster discharged 4.9 million barrels (779,100,000 liters) of oil into the Gulf of Mexico.  After several failed efforts to contain the flow, the well was declared sealed after five months.  However, reports in early 2012 indicated that the well site was still leaking. 

The incidence of Deepwater Horizon is unique also from the point that it is one of the most researched, documented and debated disasters of oil spills.  BP declared finally in 2016 that the oil spill imposed BP total loss of USD 62 billion.  18 researchers, commissioned by the U.S. National Oceanic and Atmospheric Administration (NOAA) in May 2010 estimated that the spill inflicted $17.2 billion (Rs. 117940,40,00,000) in damages on the Gulf’s natural resources.

It is also interesting to note here that in September 2014 US courts did not mince words while opining that “BP’s reckless operations, willful misconduct, and gross negligence led to the Deepwater Horizon disaster.”  U.S. District Judge Carl Barbier in New Orleans rejected BP’s assertion that Transocean, which leased the Deepwater Horizon rig to BP, and Halliburton, which was contracted by BP to do cement work on the well, deserved equal shares of blame.  “BP’s conduct was reckless,” Barbier wrote in his 153-page ruling. “Transocean’s and Halliburton’s conduct was negligent.”

Pic 3 - Gulf of Mexico

Gulf of Mexico map showing location of the spill


Not just BP or Transocean or Halliburton, in my opinion, is to be blamed for Macondo well calamity but even US administration and especially Federal Interior Department was also equally negligent about their duties.  On 5th may 2010 Washington Post carried

Pic 4 - BP oil spill satellite image

Satellite picture of Deepwater Horizon oil spill

a story.  It said “The decision on April 6, 2009, by the department’s Minerals Management Service (MMS) to give BP’s lease at Deepwater Horizon a “categorical exclusion” from the National Environmental Policy Act (NEPA) – and BP’s lobbying efforts just 11 days before the explosion to expand those exemptions – show that neither federal regulators nor the company anticipated an accident of the scale of the one unfolding (then) in the gulf.” 

To understand this accident better let us look at some basic concepts.  BP’s Macondo Prospect oil well contains (even now) billions of dollars’ worth of oil. All one needs is a 4 kilometers long straw to tap it and suck it out. The Deepwater Horizon was a floating oil rig that was designed to insert such a straw. An oil rig or an oil platform or offshore drilling rig is a massive structure with facilities for well drilling to explore, extract, store, process petroleum and natural gas which lies in rock formations beneath the seabed. In many cases, the platform contains facilities to house the workforce as well.  The picture below depicts various types of oil rigs. 

Pic 5 - Types of_offshore_oil_and_gas_structures

1, 2) conventional fixed platforms; 3) compliant tower; 4, 5) vertically moored tension leg and mini-tension leg platform; 6) spar; 7, 8) semi-submersibles; 9) floating production, storage, and offloading facility; 10) sub-sea completion and tie-back to host facility.

Deepwater Horizon oil rig was a semi-submersible type of a platform (as shown in no 8 in the above picture).  Swiss giant Transocean owned it and had leased it to BP. (Normally such a large platform’s lease rate is around USD 500,000 per day!) Deepwater Horizon was built in South Korea in 2001, and it was state of the art in every way. It could dynamically position itself with the help of satellites. It did not anchor itself to the seafloor. It actively resisted winds and currents using propellers. It could also compensate for tides and wave action on its own.  In short, although it was a floating platform, it could stay positioned precisely at one point in the sea for years together. 

Below picture shows a heavy-lift ship “Black Marlin,” transporting The Deepwater Nautilus, sister rig to the Deepwater Horizon.  Deepwater Horizon was also similarly carried into the Gulf of Mexico for drilling Macondo Prospect.

Pic 6 - Carriage of Deepwater Horizon

Vessel Black Marlin carrying Deepwater Nautilus

As we are aware, crude oil or just oil is a fossil fuel that was formed from the remains of ancient marine organisms.  Millions of years ago, algae and plants lived in shallow seas. After dying and sinking to the seafloor, the organic material mixed with other sediments and was buried. Over millions of years, under high pressure and high temperature, the remains of these organisms transformed into what we know today as fossil fuels. Coal, natural gas, and petroleum are all fossil fuels that formed under similar conditions.  Today, petroleum is found in vast underground reservoirs where ancient seas are located.  In a pool like Macondo Prospect, oil is beneath 5000 feet of water plus 13,000 feet of rock. In metric units, the numbers are 1524 meters and 3962 meters (or almost 4 kilometers deep), respectively. 

Below picture represents to show, how Deepwater Horizon had put a straw to Macondo Prospect oil reservoir. 

Pic 8 - Macondo Prospect representation

Representative picture showing Macondo prospect well along with Deepwater Horizon

The blowout preventer (BOP) shown in the above picture and concrete joints near the well mouth failed leading to a blow-out of the well.  4 kilometers below the sea level, the mixture of oil and gas is under tremendous pressure.  In the case of Macondo, the estimated pressure was around 1142 bars (we inflate our car tires at approximately 2 bars!). Naturally, with the blowout, the oil-methane mixture gushed to the sea surface with thunder and created a catastrophe.

The 2010 Deepwater Horizon disaster spread spilled oil deep into the ocean’s depths and along the shores of the Gulf of Mexico, compromising the complex ecosystem and local economies. The response and the natural resources damage assessment were the largest in the US’s history.

Ecosystems are comprised of biological, physical, and chemical components, interconnected to form a community. What happens in one location has serious, cascading effects on organisms in other parts of the ecosystem. The Gulf’s coastal wetlands and estuaries support the entire Gulf ecosystem, providing food, shelter, and nursery grounds for a variety of animals. The open waters of the Gulf also provide habitat for fish, shrimp, shellfish, sea turtles, birds, and mammals.

Considering these interdependencies during the assessment process was essential. At the same time, it was impossible to test or examine every injured bird, every sickened dolphin, or every area contaminated with oil. That was cost prohibitive and scientifically impossible. Instead, NOAA scientists evaluated representative samples of natural resources, habitats, ecological communities, ecosystem processes and linkages. To do that, scientists made 20,000 trips to the field, to obtain 100,000 environmental samples that yielded 15 million records.

A summary of the natural resource injuries based on their findings:

  1. Marshes Injured
  • Plant cover and vegetation mass reduced along 350 to 720 miles of shoreline.
  • Amphipods, periwinkles, shrimp, forage fish, red drum, fiddler crabs, insects killed.
  1. Harvestable oysters lost
  • 4 – 8.3 billion harvestable oysters lost
  1. Birds, fish, shellfish, sea turtles, and dolphins killed
  • Between 51,000 to 84,000 birds killed
  • Between 56,000 to 166,000 small juvenile sea turtles killed
  • Up to 51% decrease in the Barataria Bay dolphin population
  • An estimated 2 – 5 trillion newly hatched fish were dead
  1. Rare corals and red crabs impacted
  • Throughout an area about 400 to 700 square miles around the wellhead
  1. Recreational opportunities lost
  • About $527 – $859 million in lost recreation such as boating, fishing, and beach going

Months and years after the incidence,  the spill was being discussed as a disaster with far-reaching consequences sufficient to impact global economies, marketplaces, and policies. These potentially included structural shifts to energy policy, insurance marketplaces and risk assessment, and potential liabilities of the order of tens of billions of US dollars for one or even more significant and well-known companies – principally BP.


  1. Motherboard Blog
  2. United States Environmental Protection Agency
  3. Mongabay
  4. NOAA’s Office of Response and Restoration (OR&R) (National Oceanic and Atmospheric Administration – US Department of Commerce)
  5. Wikipedia
  6. Engineerlive
  7. Planet for Life

Milind Joshi


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