17 giugno 2010

Gulf Coast oil spill demystified: A glossary

"Top hats." "Top kills." "Berms". "Booms". As the attempts to plug the oil spill in the Gulf of Mexico become more complex, so do the terms. We break down the jargon that you might come across as you follow the story.

1. Berms: A wall or barrier of sand usually used to protect against flooding along coasts, but now it's being considered to stop oil from washing up on Gulf Coast beaches.
Context: For nearly two weeks [Louisiana Gov. Bobby] Jindal has asked the [U.S. Army] Corps [of Engineers] to approve a plan to dredge sand berms off the coast in an attempt to keep oil from reaching inland marshes.
The Christian Science Monitor: BP oil spill pushes Louisiana to desperate, massive 'berm' plan

2. Blowout preventer: A large valve at the top of a well that can be closed to stop oil from gushing into the sea in the event of a problem or when the oil rig sank a month ago, triggering the leak.
Context: BP, the well's majority owner, has been trying to stop the flow by using remote-controlled submarines to activate a valve atop the well. But the valve, known as a blowout preventer, is not working.
CNN: Stopping Gulf Coast oil leak could take weeks

3. Booms: These are long pieces of plastic tarp sewn such that they consist of flotation devices on top and a weighted skirt that sinks into the water. They are deployed along beaches to stop surface oil slicks from washing inland.
Context: “We need more boom, we need more resources, we need the materials we have requested to fight this oil and keep it out of our marsh and off of our coast,’’ Louisiana’s governor said.
Financial Times: White House faces fire over BP oil leak

4. Dispersants: Oil dispersants are chemicals that can break the oil down into small drops and prevent it from reaching the surface or the shore. Dispersants are generally less harmful than the oil itself, which is highly toxic, and they biodegrade more quickly.
Context: EPA ordered BP to find another chemical dispersant to use on the oil spill after concerns arose about the long-term effects of the substance now being used.
CNN: Feds tell BP to cut use of oil dispersants in Gulf

5. Junk shot: Debris such as shredded rubber tires, golf balls and similar objects would be shot under extremely high pressure into the blowout preventer in an attempt to clog it and stop the leak. The goal of the junk shot is to force-feed the preventer, the device that failed when the disaster unfolded, until it becomes so plugged that the oil stops flowing or slows to a relative trickle. That would be followed by a “top kill.”
Context: Using the same tubes and pipes, BP would then try a "junk shot," pumping material like golf balls, pieces of tire and pieces of rope into the blowout preventer.
CNN: How BP's 'top kill' procedure will work
6. Relief well: A well drilled into the existing well, intercepting the flow and allowing a specialized heavy liquid to be pumped into the flowing well to bring it under control. This liquid is denser than oil and so exerts pressure to stem the flow of oil.
Context: Now BP has started drilling a relief well that eventually could allow them to close off the broken well. However, that would take at least two months to work, said Doug Suttles, the BP chief operating officer.
CNN: BP to try unprecedented engineering feat to stop oil spill

7. Skimmers: A device used to recover oil from the water’s surface. There are three main types of skimmers. The Weir skimmers, for example, use a dam or enclosure positioned at the oil-water interface. Oil floating on top of the water will spill over the dam and be trapped in a well inside, bringing with it as little water as possible. The trapped oil and water mixture is then pumped.
Context: Mayors and parish presidents were critical of both the government and BP's handling of the cleanup, recounting stories of misdirected protective booms or skimmers that sat on trucks ashore.
CNN: Louisiana demands federal action on dredge plan

8. "Top hat": A top hat is a smaller version of a containment dome that BP tried to install earlier. It is a sort of upside-down funnel designed to trap the oil and channel it to the surface, again to be offloaded onto ships. The earlier four-story containment dome failed when natural gas crystals collected inside the structure, plugging an outlet at the top. BP is abandoning plans to use the “top hat” containment dome to contain the spill for now.
Context: The "top hat" oil-containment device has reached the sea floor in the Gulf of Mexico and should be in position over a leaking well head and operational by the end of the week, well owner BP said Wednesday.
CNN: 'Top hat' containment device reaches ocean floor, BP says

9. "Top kill" Not to be confused with “top hat,” this maneuver is an attempt to stop and seal the well instead of just containing it. The top kill involves pumping heavy drilling fluid into the head of the leaking well at the seafloor. The manufactured fluid, known as drilling mud, is normally used as a lubricant and counterweight in drilling operations. The hope is that the drilling mud will stop the flow of oil. If it does, cement then would be pumped in to seal the well.
Context: All previous attempts by the company to cap the spill have failed, and BP CEO Tony Hayward said the top kill maneuver will have a 60 percent to 70 percent chance of success when it is put in place as early as Wednesday morning.
CNN: Patience runs thin as BP preps untested maneuver to cap oil leak

10. Riser insertion tube: The riser insertion tube tool involves inserting a 4-inch diameter tube into the Horizon’s rise, a 21-inch diameter pipe, between the well and the broken end of the riser on the seafloor in 5,000 feet of water. The insertion tube would be connected to a new riser to allow hydrocarbons to flow up to the Transocean Discoverer Enterprise drillship located on the surface. The oil will be separated and then safely shipped ashore.
Context: After some success with the riser insertion tube, BP is preparing to try its "top kill" approach to stemming the flow of oil from the Macondo well, probably on Wednesday.
Financial Times: Moving in for the ‘top kill’

11. Oil plumes: These are underwater globules of oil that do not float to the surface of the ocean. Scientists say microscopic oil droplets are forming these deep water oil bubbles. The heavy use of chemical dispersants, which breaks up surface oil, is said to have contributed to the formation of these plumes. Scientists are worried that these underwater globs will pose a threat to the marine ecosystem and that the oil could be absorbed by tiny animals and enter a food chain that builds to larger fish.
Context: The University of South Florida recently discovered a second oil plume in the northeastern Gulf. The first plume was found by Mississippi universities in early May.
CNN: New oil plume evidence uncovered