Skip to content

The largest oil spill in American History. What happened onboard the Deepwater Horizon?

The Night it All Began

April 20, 2010, will forever be a night to remember — the night of the worst disaster in international waters. Just before 10 PM CDT, an oil drilling rig called the Deepwater Horizon exploded in flames 41 miles off the coast of Louisiana. The drilling rig was owned by Transocean Ltd., one of the world’s largest offshore drilling contractors. At the time of the explosion, the rig was under contract to BP for the purpose of drilling for oil on the Macondo Prospect, the area in the Gulf of Mexico which BP had purchased the mineral rights to.

On that fateful night, there were 126 crew members aboard the oil rig — 11 of those members were presumed dead. Two days after explosions rocked the Deepwater Horizon, the rig sank, leaving behind a gushing oil well.

The Deepwater Horizon oil spill in the Gulf of Mexico is the worst oil spill in history, leaving almost 5 million barrels of oil in the Gulf. This surpassed the 3.3 million barrels that spilled into the Bay of Campeche by the Mexican rig Ixtoc I in 1979.

What Went Wrong?

There is much speculation as to what caused the explosions. Was it flaws in the cementing process that was used to cap the well? Was it a failure of the blowout preventer (a safety mechanism designed to shear and seal the well column in the case of an emergency)?

The goal of The Deepwater Horizon was to drill a well to tap the oil reservoir on the Macondo Prospect. Once the oil was reached, the plan was to cap the well column with three cement plugs so that another rig could return at a later time and remove the oil. The contractor for the cementing process was Halliburton Inc. The official investigation into the cause of the spill has revealed that BP and Halliburton had agreed to use a different cementing process than what was normally done. In this case, the cement plugs were infused with nitrogen. Adding nitrogen to the cement makes the process much more difficult because the cement is much harder to handle. If any air bubbles were to form, the reliability of the cement plug would be in question. Because of this slightly unusual design, there was uncertainty as to whether the cement caps used were faulty. Halliburton made a statement saying that the cementing process had been completed 20 hours before the explosions on the Deepwater Horizon.

The other likely cause of the spill was a malfunction of the blowout preventer. The blowout preventer is the final safety mechanism in preventing a rush of oil and gases from the well up the column to the rig. If the crew were to lose control of a well, the blowout preventer — a blind shear ram — was to cut through the drill pipe and seal the well, thus preventing any disaster. Unfortunately for the crew of the Deepwater Horizon, the blind shear ram fell a few inches short of sealing the well. Reports indicate that had the blowout preventer achieved its purpose, the Deepwater Horizon would not have been riddled by explosions and sunk to the floor of the Gulf.

Warning Indicators

The Deepwater Horizon began drilling on the Macondo Prospect in February 2010. Since then, there had been many indicators of impending trouble. During February and March, BP continuously struggled to maintain well control once the drilling began. The initial drill pipe got stuck, and had to be severed, and the process continued elsewhere. Tools and drilling fluid called “mud” were lost to the well.

On many occasions prior to April 20, there were issues with the blowout preventer. The issues were both human and mechanical in nature. In addition to these problems the blowout preventer tests were conducted at lower pressures than previously reported which meant the test’s validity was compromised (along with safety).

“Nothing is more terrible than ignorance in action.”

“No man should judge unless he asks himself in absolute honesty whether in a similar situation he might not have done the same.”
Victor Frankl

A Matter of Negligence?
The day after the rig explosion, a lawsuit was filed in Louisiana against BP and Transocean on behalf of the eleven missing men. The lawsuit claimed negligence on behalf of both companies. Since then, many more lawsuits have been filed by surviving crew members and affected businesses.

The investigations have brought to light many bad decisions and corners cut concerning the digging of the oil well on the Macondo Prospect. BP appears to be the primary target of all the blame, though there are others who contributed to the decisions that led to the dreadful events of April 20, 2010.

The Minerals Management Service (MMS), a branch of the U.S. Interior Department, had BP’s exploration plan for the oil well on file. In this plan, BP stated that it was unlikely that a spill would occur from the proposed drilling activities in 5,000 feet of water and that should a spill actually occur, no adverse impacts were expected. The MMS had accepted this plan. Now, there is a claim that the exploration plan did not address the technology that would be needed to control a spill at the depth they were drilling, as is evidenced by the continued leaking of oil into the Gulf of Mexico. The MMS granted BP a “categorical exclusion” from the detailed environmental analysis of the exploration project that is typically required by the National Environmental Policy Act. The MMS states that they have given out many of those exclusions to other companies as well.

According to Transocean and BP, safety is the foremost priority when drilling for oil. Any crew member on a rig has the authority to halt drilling if they deem something unsafe. Interviews with survivors of the Deepwater Horizon reveal that the safety concerns voiced by the crew were often disregarded. Issues with the blowout preventer were never fully investigated or fixed. There had been issues with gas flares from the well itself. Well control had obviously been an issue from the get-go. Even on the day of the explosions, there were problems that were not properly tended to.

Five hours before the initial blast, tests showed that the gasket seal to the blowout preventer was leaking. It had taken several attempts to get the pressure levels back under control. Additionally, BP and Transocean managers had a different idea as to how to seal the well once the drilling was complete. The Transocean manager wanted to follow normal procedure and fill the drilling column with “mud” — a drilling mixture made of clay, water, and minerals used to keep downward pressure on the well — while the three cement plugs used to seal the column were put in place. The BP manager, who ended up overruling the Transocean manager, wanted to begin removing the “mud” before the last of the plugs was in place. Doing this would reduce the pressure controlling the well before the plugs were properly in place. Although this process would be faster than the normal procedures, it was not as safe, because fluid circulation would be altered. There would be more fluid going out of the column than in, thus leading to unsafe pressure conditions. BP was already very behind in their schedule, as well control and getting stuck had cost a lot of time and money shortly after drilling began. In an attempt to cap the well sooner, the BP manager elected to alter the typical process. A White House investigator stated that had the “mud” been left in the column per normal procedures, a blowout probably would have been prevented.

Back to Crime Library

Back To Top