BP was already building a backup version

BP was already building a backup version In the procedure, called a top kill, the mudAromatic would be used to overcome the pressure of the rising oil, stopping the flow. The mud would be followed by cement, which would permanently seal the well.

Mr. Wells said Sunday that BP was a week to 10 days away from trying the maneuver.

The mud would be pumped from a drill ship, the Q4000, that is in place on the surface. Mr. Wells said the ship had more than 2 million gallons of mud on board — far more than needed — to pump into the well, which had reached about 13,000 feet below the seabed when the accident occurred.

In a brief interview, Mr. Wells said that a “junk shot,” an effort to clog the blowout preventer with golf balls and other objects before the mud is used, was still a possibility.

But in an apparent indication of the tube’s success, BP was already building a backup version.

The tube is basically a five-foot-long section of pipe outfitted with rubber seals designed to keep out seawater, attached in turn to a milelong section of pipe leading from the drill ship to the seafloor.

It was one of several proposed methods of stanching the flow of at least 210,000 gallons of oil a day that has been threatening marine life and sensitive coastal areas in Louisiana, Mississippi, Alabama and Florida. BP officials have emphasized that none of the methods have been tried before at the depth of this leak.

At the briefing, Mr. Wells was asked about reports from a research vessel that discovered the huge plumes of oil. He said that he did not know anything about them, but that the Unified Area Command, the cooperative effort involving BP and state and local agencies, was seeking more information.

The plume reports added to the many questions that have been raised about the amount of leaking oil, which many scientists have said is far higher than the official estimate of 5,000 barrels, or 210,000 gallons, a day. That estimate was reached using satellite imagery, flyovers and visual observation, company officials have said.

The reports also raised concerns about the use of oil dispersants underwater, which the Environmental Protection Agency approved on Friday after several tests. Normally, dispersants are used on the surface, and scientists have said that the effects of using them underwater are largely unknown.