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May 25, 2010 6:01 PM by Melissa Canone

BP Going in with the "Top Kill"

COVINGTON, La. (AP) - BP is going in for the kill. The trick is
to do the job quickly and cleanly.
As early as dawn Wednesday, the oil company will try to choke to
death the gusher at the bottom of the sea by force-feeding it heavy
drilling mud and cement - a tactic called a "top kill" that is
routinely used above ground but has never been tried 5,000 feet
underwater.
If it's not done just right, it could make the leak worse.
The stakes for BP are high, with politicians and others losing
patience with the company over its inability to stop the oil leak
that sprang more than a month ago after an offshore drilling rig
exploded. Eleven workers were killed, and by the most conservative
estimate, 7 million gallons of crude have spilled into the Gulf of
Mexico, fouling Louisiana's marshes and coating birds and other
wildlife.
"We want what everybody wants - to stop the flow at the source
as quickly as possible," said BP spokesman John Curry. "We
understand the frustration and we just want to bring this to
closure."
Engineers were doing at least 12 hours of diagnostic tests
Tuesday. They planned to check five spots on the well's crippled
five-story blowout preventer to make sure it could withstand the
heavy force of the mud. A weak spot in the device could blow under
the pressure, causing a brand new leak.
BP has been drafting plans for the top kill for weeks but had to
delay it several times as crews scrambled to assemble the equipment
at the site 50 miles off the coast. A flotilla of rigs, barges and
other heavy machinery stood ready there Tuesday.
A top kill has worked on aboveground oil wells in Kuwait and
Iraq. BP CEO Tony Hayward pegged its chances of success in this
case at 60 to 70 percent.
Kent Wells, a BP senior vice president, cautioned that engineers
are speeding through a planning process that would normally take
months. He warned that the top kill could be delayed or scuttled if
Tuesday's pressure readings are bad.
Once the test results are in, scientists with the federal
Minerals Management Service will examine them and BP will consult
with government officials before deciding whether to press on,
Curry said.
If all goes as planned, engineers will pump fluid twice as dense
as water from two barges into two 3-inch-wide lines that will feed
it into the blowout preventer. Crews plan to pump it in at a rate
of 1,680 to 2,100 gallons per minute in hopes of counteracting the
upward pressure of the oil gushing to the surface. They stockpiled
some 50,000 barrels of the heavy mud, a manufactured substance that
resembles clay.
Wells said it could take anywhere from a few hours to two days
to determine whether the top kill is working.
If it succeeds, BP plans to follow through by injecting a stream
of cement to permanently seal up the well. They may also install a
new blowout preventer on top as a fail-safe.
Live video of the leak has been available online for the past
few days, but Rep. Edward J. Markey, D-Mass., said he learned
Tuesday that the feed would be shut off while BP attempts the top
kill. A BP spokesman said the company has not yet decided.
"This BP blackout will obscure a vital moment in this
disaster," Markey said. "After more than a month of spewing oil
into the Gulf of Mexico, BP is essentially saying to the American
people the solution will not be televised."
Bob Bea, an engineering professor at the University of
California at Berkeley, said the procedure carries a high risk of
failure because of the velocity at which the oil may be spewing.
If some of the higher estimates of 3 million to 4 million
gallons a day are correct, "it's going to spit everything back in
your face," Bea told The Associated Press. He estimated that
anything above 1.6 million gallons a day would be too much for a
top kill to work.
Nevertheless, "they're trying and that's a good thing," Bea
said. "I certainly pray that it works, because if it doesn't
there's this long waiting time" before BP can dig relief wells
that would cut off the flow.
In addition to the danger of the blowout preventer springing a
leak, the risks include the possibility that the mud could tear a
new hole in the leaking well pipe.
If the top kill doesn't work, or makes the problem worse, BP
will probably turn to a containment box resting on the seafloor. It
is a smaller version of the 100-ton box the company lowered several
weeks ago in hopes of capturing much of the oil. That larger device
was clogged with ice crystals and BP had to abandon it, but the
company hopes the smaller version might work better.
BP has had limited success with a mile-long tube it installed
more than a week ago to siphon up some of the oil. The device has
captured more than 500,000 gallons but has also allowed untold
amounts to escape into the sea.
The company's backup plans include a junk shot, which involves
shooting golf balls, tire scraps, knotted rope and other assorted
objects into the well to clog it up.
BP executives say the only guaranteed permanent solution is a
pair of relief wells crews have already started drilling, but that
will take at least two months.

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