What is a blowout preventer?

from how Stuff works dot com where smart Happens. I am Marshall Brain with today's question, what is a blowout preventor and how does it work? And why did the one in the Gulf of Mexico fail? As everyone is now aware, there's a gigantic oil geyser on the floor of the Gulf of Mexico that's spewing more than a million gallons of oil per week into the gulf. The Deepwater Horizon platform, which had been sitting over the well, endured an explosion and fire that eventually caused that rig

to sink. When the deep Water Horizon exploded, there's a gigantic piece of failsafe equipment on the well that should have prevented any oil from leaking out. This piece of equipment is called a blowout preventer or BOP. Its job is to immediately plug the well in the event of an emergency. Obviously, the blowout preventer below the deep water horizon failed, so let's take a look at how blowout preventers are supposed to work in any well drilling operation.

The blowout preventer is one of the first pieces of equipment that appears on the ocean floor. It's a massive structure. Imagine a gigantic set of valves and hydraulic pistons, all encased in steel. It's several stories tall and ways many tons. It attaches to the wellhead, the pipe and flange system that extends from the ocean floor at the top of the well. During drilling, the drill fits down through the

blowout preventer and into the well. You can understand why a blowout preventer is needed if you think about what happens during drilling. The goal of any drilling operation is to find a lake of oil and or natural gas buried deep under rock. In the case of the deep water horizon, the water in the gulf was a mile deep, and then the drill punched through more than two miles of rock to reach the oil. All that water and rock on top of the oil creates pressure tens of

thousands of pounds per square inch of pressure. The oil wants to burst out of the ground once the underground lake is punctured. What normally keeps the oil in place is the pressure of the drilling mud. This mud is a natural part of the drilling process. As the metal drill bit cuts the rock, The mud helps pull the bits of rock out of the hole, and it also

lubricates the bit. The mud is always circulating under pressure, and that pressure opposes the pressure of the oil that wants to come out, keeping the oil in the well. But what if something goes wrong during drilling? The well can kick. The kick comes in the form of too much pressure. In the worst cases, that pressure can blow all the mud right back up out of the well and create a geyser of high pressure oil and or natural gas. The blowout preventer is there to handle these situations.

If the drilling crew loses control of the well, the valves on the bob are supposed to kick in and stop the flow. One approach, called an annular bob, can close around the drill and seal things off at the top of the blowout preventer, or two hydraulic rams can slide in from the sides and force a rubber seal across the pipe. In the worst case scenario, a sharing ram can cut right through everything in the pipe and

seal it off. It might be necessary to later drill another well once a BOB triggers, but that is better than an unstoppable geyser of oil, especially on the ocean floor. In the case of the deep Water Horizon, the well did in fact kick with a huge bubble of natural gas. Once the bubble escaped at the surface, the gas exploded and burned, eventually sinking the rig, But the BOB should

have deployed and stopped that leak. Neither the signals from the rig nor robotic subs after the fact have been able to activate the rams in the BOB, or the BOB may have partially activated and jammed for some reason, only blocking part of the flow coming out of the well.

Now what rescue cruise might be able to attach a second BOP on top of the failed BOP and activate it, or they may try to shoot shredded tires and other junk into the bob under gigantic pressure to try to plug the pipe, or they will drill relief wells that take the pressure off and cap the first well. No matter what, it will take a long time to clean up the mess from this failed piece of equipment. Do

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