US Government: No Decision Yet on How to Proceed with 'Bottom Kill'

HOUSTON (Dow Jones Newswires), Aug. 18, 2010

U.S. scientists and BP engineers are still pondering how to intersect a damaged deep-water well in the Gulf of Mexico to fill it with mud and cement, and there is no clear indication of how soon they might proceed, the head of the federal oil-spill response effort said Wednesday.

Responders are concerned that pumping mud into the well's annulus (an area between the well and the surrounding rock formation) could end up breaking a cement seal placed at the top of the well earlier this month. The operation, known as "bottom kill," is expected to signal the final demise of the well that unleashed the largest accidental offshore oil spill in history after its blowout last April.

Right now, BP is trying to get a better read on pressure signals coming from the well. The information will let responders decide whether to go ahead with the drilling of a relief well to perform the bottom kill, or to remove a containment cap that sits on top of the well and replace it with a stronger blow-out preventer that can withstand any rupture of the cement seal before continuing to drill.

"I can't tell you how many days it will take to do that," to make the decision, retired Coast Guard Admiral Thad Allen, who heads the response effort, said during a conference call with reporters. During a conference call Monday, Allen had said that the decision would be made Tuesday or Wednesday.

Respondents are bringing a drill-ship carrying the new blow-out preventer over the site of the well, Allen said; concurrently, they are flushing any "extraneous materials" out of the sealing cap and filling it with seawater to better understand pressure variations at the well.

The delay marks an unexpected complication in a saga that began when Transocean's Deepwater Horizon drilling rig blew up last April, killing 11 and unleashing nearly five million barrels of crude oil over the course of three months. The spill came to an end in mid-July, when BP installed a sealing cap on top of the well; the seal was strengthened in early August, when responders successfully plugged the top of the well with cement, an operation known as "top kill." The "bottom kill" is expected to culminate the effort of killing the deep-water well permanently.

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