BP is still knee-deep into executing its "top kill" maneuver--what some have called its "most ambitious effort to date" to plug the ruptured well in the Gulf that has spewed millions of gallons of crude. There have been some early reports of progress from BP and the Coast Guard, though the procedure is not complete and could still fail at any time.

The top kill, as the Los Angeles Times explained with this helpful graphic, involves filling the blowout preventer with heavy drilling mud in order to keep down the oil before sealing the well with cement.

Using mud to stop the oil from surging up--that's just what workers on the rig failed to do in the hours right before the explosion. Instead, they removed mud from the well, replacing it with seawater. The decision was a contentious one, according to new accounts of feuding between Transocean and BP in the hours before the explosion.

In a hearing on Wednesday, the chief mechanic on Transocean's Deepwater Horizon rig testified that a BP representative, in an argument that lasted for hours, "overruled drillers from rig owner Transocean and insisted on displacing protective drilling mud from the riser that connected the rig to the oil well," according to The Times-Picayune of New Orleans.

As one petroleum engineering expert pointed out to The New York Times, it is not unusual to remove mud before finishing off a well, but a senior Transocean manager complained that BP was "taking shortcuts" in removing the heavy mud and replacing it with seawater, according to witness statements reported on Wednesday by The Associated Press.

The argument between Transocean and BP was earlier reported on "60 Minutes," and has since been confirmed by testimony and company documents submitted to Congress.

When Scott Pelley of "60 Minutes" asked Bob Bea, a UC Berkeley engineering professor, why BP would ask for the removal of the mud, Bea responded:

"It expedites the subsequent steps."

"It's a matter of going faster," Pelley remarked.

"Faster, sure," Bea replied. ...

"If the 'mud' had been left in the column, would there have been a blowout?" Pelley asked.

"It doesn't look like it," Bea replied.

Now that BP has been desperately trying to inject the mud back into the system to plug the well, it appears as if the decision to remove it from the system may not have been wise, to say the least.

BP said the top kill could take up to two days to complete, and results will not be immediate. It has promised to provide live video feeds from the seabed throughout the top kill procedure, but its website's transmissions have been intermittent. We've been watching and have had more luck watching the same feeds elsewhere.

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