The Deepwater Horizon well is most likely spewing at least 25,000 barrels of oil a day and may be producing 40,000 or even 50,000 barrels a day, according to preliminary research from two teams of scientists appointed by the federal government to study the flow from the dark geyser at the bottom of the Gulf of Mexico.

Another scientific team, using a different methodology, estimates a somewhat more modest flow of 12,600 to 21,500 barrels.

The numbers are all over the place, acknowledged U.S. Geological Survey director Marcia McNutt in a news conference Thursday announcing the findings. Several other teams are preparing their own figures in what has been a protracted and often frustrating effort to get a handle on exactly how much oil is surging from the Macondo reservoir 3 1/2 miles below the surface of the gulf.

One group, the so-called "plume team," examined video of the leaking riser pipe before it was sheared on June 3. The team concluded that 20,000 to 40,000 barrels may be flowing, with 25,000 to 30,000 barrels being the most likely rate.

If that estimate is correct, and the flow has been more or less consistent, approximately 1.3 million to 1.5 million barrels -- or 53.6 million to 64.3 million gallons -- of oil have emerged from the well since the April 20 blowout.

That is roughly five to six times the amount spilled in Alaskan waters in 1989 by the Exxon Valdez.

A team from the Woods Hole Oceanographic Institute has studied the leak with instruments normally used in research on deep-sea hydrothermal vents. That team estimated the flow at 25,000 to 50,000 barrels a day, said McNutt, who cautioned that the figure is very preliminary.

Another team, called the Mass Balance Team, analyzed satellite images and tried to correct for oil that had evaporated or been skimmed, burned and dispersed. Having earlier estimated the flow at 12,000 to 19,000 barrels a day, the team nudged its new estimate slightly upward, to 12,600 to 21,500 barrels a day.

The flow rate is significant on several fronts. First, it gives the government and BP a sense of how much capacity they will need among surface ships to handle all the oil gushing out the well and up a pipe to the Discovery Enterprise drillship, which is capable of processing about 18,000 barrels a day.

Other ships are being added to the effort. The site above the blown-out well has become crowded with 25 to 30 vessels at any given time, Coast Guard Adm. Thad Allen, the government's point man on the disaster, said Thursday.

Second, the fines that BP faces for polluting the gulf will be tied to how many barrels of oil have leaked.

Third, the higher figures call into question the circumstances that led to the much lower estimates of the spill earlier in the crisis. On April 28, after having received estimates of the size of the spill from BP and the National Oceanic and Atmospheric Administration, the Coast Guard announced that the well was leaking about 5,000 barrels a day.

That remained the official estimate for weeks.

Last month, with the government sticking to an estimate of 5,000 barrels a day, and independent scientists arguing that the amount had to be much higher, Allen appointed the Flow Rate Technical Group to come up with a better estimate.

Allen rejected the suggestion this week that the government has been lowballing the flow rate.