Oil Spill Answers: Why The Blowout Protector Failed

With all the finger pointing and blame going around and the Gulf, there’s only one thing that can be definitively blamed: the blowout preventer (BOP) on the Deepwater Horizon.

The blowout preventer in this case was a 53 foot tall, 325 ton and $15 million piece of equipment that rests at the bottom of the ocean, and it's sole job is to keep gas from rushing too quickly up the rig, causing the type of explosion that started the current spill. 

Despite it's huge size and incredibly important function, the BOP is an essentially simple machine. It both keeps the drill string -- the tube that transmits oil to the rig -- secure and regulates the flow of the drill string's contents. At the top of the BOP lies it's key function: two large rubber pads that work in what's called a "hugging mechanism". When controlled by remote from the rig, these pads press against the string very tightly, (hence the hugging moniker). It's similar in concept to squeezing a rubber hose shut with your fingers to alter or stop it's stream: when that potentially lethal large burst of oil or gas shoots out of the earth and into the pipe, the blowout protector can control the pressure or even shut off the flow entirely.

BP’s blowout preventer had every reason to be in decent shape, but was simply poorly maintained. A Congressional investigation from the House Oversight Committee this week found that the blowout preventer had a dead battery in its control pod, leaks in its hydraulic system, and a cutting tool that wasn’t strong enough to shear through joints that made up 10 percent of the drill pipe.

The biggest problem, however, came when the rig hit the resevoir and began pumping oil. Under standard operating procedures, the string is securely contained in the blowout preventer, which keeps it steady. But at one point, when the rubber pads were tight around the pipe, a technician in the rig accidentally bumped a joystick that moved the pipe upward about 15 feet. This both damaged the pipe and the rubber.

As engineer Mike Williams disclosed in his 60 Minutes interview, the pieces of rubbed-off rubber from the hugging mechanism began to flow upward with some oil, which concerned some people in the rig. But unfortunatly, there was no way to follow up on those fears. Earlier in the trip, the battery which that powered the communication system between the BOP and the rig died, and workers were unable to moniter any problems that might occur. (According to the Congressional report,  BP officials on site looking to save time and money and encouraged workers on the rig to press on without changing the battery.)

And so the drilling continued, until the rig hit upon a particularly forceful stream of oil and methane gas. The damaged blowout protector was unable to regulate the force,


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