BP Begins 'Static Kill' to Plug Oil Leak

Crews should know within hours whether the mud is pushing down the oil as envisioned.

But engineers still won't know for more than a week whether the attempt achieved its goal because they have to wait for completion of an 18,000-foot relief well to reach the reservoir from the bottom. "This is a really positive step forward," retired Coast Guard Adm. Thad Allen said earlier, calling it "good news in a time where that hasn't been very much good news, but it shouldn't be a cause for premature celebration."

Engineers began slowly pumping mud down through the well at 3 p.m. for the so-called "static kill," following a successful test conducted hours earlier, response officials said.

During a news conference that began 30 minutes after the start of the procedure, BP Senior Vice President Kent Wells said he could not then say whether it was working.

Energy giant BP began pumping mud Tuesday into the blown-out oil well in the Gulf of Mexico as part of efforts to seal it off for good.

In a statement, the company said the "static kill" procedure began at 3 p.m. (CDT). The company went ahead with the step without waiting for a pair of costly relief wells to be finished.