Geology And Geophysics

How to contain an Offshore Oil Leak



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"How to contain an Offshore Oil Leak"
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An oil spill is just about the worst type of natural disaster in a large body of water. It might be thought of as the wildfire of the ocean: it leaves nothing and no one untouched, decimating populations of every species within its reach. The only way to get rid of it is by deploying tens of thousands of men to stop its advance and clean up the damage. Or you can simply wait for it to "burn itself out."

There are two types of oceanic oil spill. There are those that result from the crash and breakup of a large tanker, and those that result from oil well explosions (usually associated with problems in the cementing process). By and large, the procedures for dealing with both are the same. They generally look something like this, although all three phases described here are usually engaged in simultaneously to deal with different aspects of a leak.

PHASE 1: CONTAINMENT

Oil does not dissolve in water. Instead it forms a narrow layer on the water's surface, and this means that a single gallon of oil can cover several football fields of surface area. To contain the oil's natural spread away from the leak, the first step is deploying "booms." A "boom" is a sophisticated, and much larger version of the noodle children use in the pool. By using networks of these booms, the environmental damage can be contained somewhat. This reduces the total area that the oil must later be removed from once the leak has been plugged.

PHASE 2: PLUGGING THE LEAK

In the case of an oil tanker that has been punctured, it may sometimes be possible to repair the damage too the tanker, or to offload some of the oil in it other ships. Both bring closer the point in time when the oil stops being released, and both reduce the total amount released in the spill.

In the case of a blown-out oil well, the options are more complicated. The first step is usually to place a "dome" on the leak site, and then pump all the oil out through the top of the dome. This dome is essentially an upside-down funnel, that is so heavy that its weight essentially acts as a watertight seal. After this has been accomplished, "relief wells" are drilled. These are holes in the bedrock that are cut towards the leaking well at an angle. Because the leaking well is under such high pressure that it can't be plugged directly, the relief well intersects the leaking well, and then thousands of tons of heavy mud are pumped into it to stop the leak.

PHASE 3: REMOVING THE OIL

There are a number of techniques to remove oil that has already been spilled. There are chemical dispersants, dropped from planes onto the ocean. The dispersants act like detergent, allowing the oils to break down and mix in with the water. There are also "controlled burns," which are like intentional brush fires in a forest. Skimmer ships use tools to skim the first eight of an inch or so off the surface of the water, and collect it in large on-board tanks. A new option that is beginning to be explored by scientists is the use of nanotechnology to develop robots that could destroy oil at the molecular level, and actually eliminate the danger of oil spills altogether.

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