Attempt at 'top kill' method to clog oil leak delayed

May 22nd, 2010 in Earth / Environment

A make-or-break attempt to clog a ruptured pipe gushing oil into the Gulf of Mexico with a method dubbed the "top kill" has been delayed until at least Tuesday, officials said Friday.

BP, which leased the Deepwater Horizon rig that exploded on April 20, has so far managed only to stem the flow of oil using a mile-long tube inserted into the ruptured pipe.

That tube -- which became operational on Sunday -- is suctioning up an average of about 2,000 barrels of oil a day to a waiting ship but significant amounts of oil are still seeping into the Gulf.

It will take at least two months for relief wells to be completed and hopes of stopping the flow are currently pinned on the "top kill" method, which aims to inject heavy fluids into the well and then seal it with .

The operation was initially scheduled to take place on Sunday, but has been delayed because of the time needed to get the equipment in place using underwater robots, BP said.

"Our current forecast for when this operation will take place will be sometime in the early part of next week," said BP Chief Operating Officer Doug Suttles.

"Our best estimate is probably Tuesday, but I will stress that these operations are quite complex and we won't start the operation until all the equipment is staged."

Suttles declined to say whether the delay was caused by concern about whether current estimates of the flow rate are radically off base.

"We've said since quite early on this that our best estimate was somewhere around 5,000 barrels per day, but with a wide range," he told reporters.

"As we do the design for top kill that same assessment is what we're designing that job off and that same assessment is what we're designing the application of dispersants off of as well."

Independent experts examining video of the ruptured pipe have estimated that the flow from the two leaks could be as high as 120,000 barrels per day.

A team of government and academic experts is currently working on developing an accurate and peer-reviewed estimate of the flow rate and total size of the spill, but officials would not say when that information would be released.

The firm is also considering combining the "top kill" operation with a "junk shot," where golf balls, rubber tire parts, plastic and other materials would be injected under pressure into a huge valve known as a blowout preventer to clog it up.

The "junk shot" could be risky as experts have warned that tinkering with the blowout preventer -- a huge 450-ton valve system that should have shut off the -- could see crude shoot out unchecked at up to 12 times the current rate.

(c) 2010 AFP

"Attempt at 'top kill' method to clog oil leak delayed." May 22nd, 2010. http://phys.org/news193714374.html