http://www.npr.org/blogs/thetwo-way/2010/05/are_last_best_hope_relief_well.htmlAre BP's Last, Best Hope Relief Wells Sure Things?
So the question is, are they 100 percent effective? The answer seems to vary according to which source you consult.
For instance, note the conditionality in a Discover magazine article quoting Jerry Milgram, a Massachusetts Institute of Technology professor the article describes as one of the world's leading experts in marine engineering.
"In this case it's kind of hard," said Milgram. "You are drilling through mostly rock. It's not going to be fast."
When the same oil-bearing rock is eventually reached by the relief well drill rig, the sealing of the broken well can finally begin.
First, seawater is pumped into the rock through the relief well. If all goes according to plan, that water should make its way into the lower end of the leaking well, displacing oil. If that succeeds, the next step is to pump in a mineral mud, which follows the sea water up the broken well. Once that mud fills the well, concrete can be pumped into the relief well.
"If you get a tall tower of mud, and if you're lucky, you'll stop it," said Milgram. "The next day you pump concrete and then the well is dead."
The mud and concrete work by their by density and shear weight, which is enough to counter the highly pressurized oil moving up the well.There are a lot of "ifs" in that passage. Clearly, many pieces will need to come together if the relief wells are to work.
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