Deepwater Horizon Oil Spill: Causes, Effects & Facts

Instructor: Christopher Muscato

Chris has a master's degree in history and teaches at the University of Northern Colorado.

The Deepwater Horizon spill was the worst oil disaster in US history. In this lesson, we'll talk about why it happened and what sort of impact it had on wildlife and humans alike.

The Deepwater Horizon Oil Spill

We need oil. Currently, our technologies rely on our ability to extract natural oils from the ground and process them into useable products like gasoline. So, using ingenious feats of engineering, oil drills were built thousands of feet below the surface of the ocean. The problem we weren't truly prepared for was this: what happens when one breaks?

In April of 2010, the Deepwater Horizon oil drilling platform ruptured, and then exploded. Eleven people were killed and the rig started pouring oil into the Gulf of Mexico. It was the worst oil spill in US history, and one that would impact the nation for years to come.

The US coastguard attempts to contain the Deepwater Horizon explosion

The Disaster

Deepwater Horizon was an oil rig built in the Gulf of Mexico (about 41 miles off the coast of Louisiana) by an offshore-drilling corporation called Transocean, but it was leased and maintained by the British oil company BP. BP had recently built a new concrete cap in the core on the rig (installed by the company Halliburton), which was supposed to contain the natural gas being released by the drill. The concrete, as it turned out, had been mixed with a nitrogen gas to speed up the curing process, and due to BP instructions was installed and maintained improperly. Basically, when you combine this faulty cap with poor installation, a failure to maintain the equipment, and the crushing pressure of the deep ocean, bad things happen.

On April 20 of 2010, the concrete cap cracked, and natural gas shot up the rig to the platform. Exposed, it ignited and exploded. Eleven workers were killed, and another seventeen were injured. Two days later, the burning rig collapsed entirely (despite efforts to stabilize it). So, what did this mean? Imagine having a soda can with a single straw penetrating the lid, and shake that soda as hard as you can. As long as you keep your finger covering the straw, you can control how much soda is released. But then remove your finger.

That's basically what occurred. BP had tapped into oil below the seafloor, but when the rig capsized all that oil began pouring directly into the ocean. According to official estimations by the US government, the Deepwater Horizon rig was pumping 60,000 barrels of oil into the ocean per day at the worst of the disaster.

The oil spill, as seen from space


BP, Transocean, and the US government all immediately began working to stop the oil leak. The rig had a failsafe mechanism in place, but it failed. Allegedly the buildup of pressure on the night of the explosion damaged it, although the mechanism may have simply been faulty from the start. A containment dome was brought in to contain the worst of the leaks, which didn't work, and drilling mud was used to try and block the flow. That failed too.

Finally, in May a cap was fitted that slowed the leak and, more importantly, allowed BP to start siphoning leaking oil directly from the rig. The cap was upgraded and eventually replaced with a better fit. By the time that the Deepwater Horizon oil leak was contained, over 80 days had passed and 4.9 million barrels of oil had spilled into the Gulf of Mexico. That's 205 million gallons. Of that, about 800,000 barrels had been siphoned or reclaimed.

Cleanup and Impact

This was a genuine disaster. The Gulf of Mexico is home to some of the most important ports in the Western Hemisphere, where massive amounts of international travel and trade are conducted. The Gulf also contains massive fish populations, many of which are very important commercial products. It didn't take long before the oil spill reached coastlines either, with about 1,100 total miles of shores from Mississippi to Florida being coated in oil. The sand beaches were hard enough to clean, but a lot of this coast, particularly around Louisiana, is composed of deltas, marshes, and estuaries.

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