June 15th, 2010
11:45 PM ET

How the oil-disaster flow estimates have evolved

U.S. government officials on Tuesday said they now estimate the ruptured BP well in the Gulf of Mexico is spewing 35,000 and 60,000 barrels (1.5 million gallons to 2.5 million gallons) per day; that's significantly more than the first estimate of 1,000 barrels per day in late April.

Below is a recap of the different estimates that officials have made, and when they made them, since the disaster began with the explosion of the Deepwater Horizon oil rig on April 20.

- April 23: Three days after the explosion of the Deepwater Horizon rig, and one day after the rig sank, Coast Guard Rear Adm. Mary Landry said crews were cleaning up a 1- by 12-mile-long oil slick spreading through Gulf waters. She said crude oil did not appear to be leaking out of the wellhead but that remote vehicles would survey the scene. BP officials had said a day earlier that BP they did not know whether oil or fuel was leaking from the rig. But BP Vice President David Rainey said: "It certainly has the potential to be a major spill."

- April 24: Landry said oil was leaking from two places - later to be clarified as two places on the riser pipe extending from the well's blowout preventer - at a preliminary estimate of about 1,000 barrels (42,000 gallons) a day. Officials later said that the two leaks were found within 36 hours of the April 20 explosion.

- April 28: Landry said the estimated amount of oil spilling into the Gulf of Mexico has increased to 5,000 barrels (210,000 gallons) a day, five times the initial estimate. The new estimate was based on analysis from the federal National Oceanic and Atmospheric Administration, she says. Also, BP official Doug Suttles said the company has found a third leak in the riser pipe.

- May 2: Coast Guard Commandant Adm. Thad Allen said it was impossible so far to know how much oil will eventually leak.

"We lost a total well head; it could be 100,000 barrels [4.2 million gallons] or more a day," Allen told CNN's "State of the Union." The official estimate, though, remained at 5,000 barrels (210,000 gallons) a day.

"This spill, at this point in my view, is indeterminate," Allen said. "That makes it asymmetrical, anomalous and one of the most complex things we've ever dealt with."

- May 13: After BP released underwater video footage of the leak, independent experts such as Purdue University associate professor Steve Wereley said the flow rate is probably much higher than the official estimate.

Wereley estimated that about 70,000 barrels (2.94 million gallons) of oil were leaking each day, based on an analysis of video of the spill. "You can't say with precision, but you can see there's definitely more coming out of that pipe than people thought," he said. "It's definitely not 5,000 barrels a day."

- May 27: A panel of government experts estimated the well is spewing oil at a rate of 12,000 to 19,000 barrels (504,000 to 798,000 gallons) a day, U.S. Geological Survey chief Marcia McNutt said.

- June 10: The panel of government experts, called the Flow Rate Technical Group, estimated the well was leaking 20,000 to 40,000 barrels (840,000 to 1.7 million gallons) per day through June 3. The figure was calculated in part by using high-definition video that BP released after demands from members of Congress.

The new estimate was of the well's flow rate before BP's cutting of the damaged riser pipe extending from the well's blowout preventer on June 3, McNutt said. After BP cut the riser that day, it placed a containment cap over the preventer's lower marine riser package to capture some of the leaking oil.

Scientists estimated that the spill's flow rate increased by 4 to 5 percent after the well's riser pipe was cut last week in order to place the cap atop the well.

BP said that with the cap, it was capturing about 16,000 barrels daily and sending it to a ship on the surface. Before that, BP was capturing some oil through a siphon inserted into the well riser.

- June 15: Government officials increased the estimate to between 35,000 and 60,000 barrels (1.5 million gallons to 2.5 million gallons) per day.

The change was "based on updated information and scientific assessments," the Deepwater Horizon Incident Joint Information Center said.

"The improved estimate is based on more and better data that is now available and that helps increase the scientific confidence in the accuracy of the estimate," it said.

soundoff (141 Responses)
  1. Mark

    I am a college student in Los Angeles, Ca and I have come up with my own estimate on how much oil has leaked from the Deep Horizion's wellhead. My calculations exceed "the experts" worst case scenerio and are based on simple math but present a logical formula.
    Think of this disaster from a perspective of scale. You will see how terrible this disaster really is. I am basing my estimate on a simple one inch garden hose and my 200 gallon aquarium. It takes less than an hour to fill. For this calculation I am assuming that the pressure of the leak is at least equal to my city water pressure. The inside diameter of the leaking pipe is 20 inches, now do the math. 3.1416(10)^2(200)(24)(58)=274,771,071.5904 gallons of oil leaked into the gulf as of 6-16-10. This is just an estimate, assume the pressure and flow of the well is greater than my estimate and watch the numbers increase exponentially. BP has drilled deep into the earth's crust and created a situation that exceeds our technology to remediate. All of the "solutions" have been trial and error, the relief wells may also fail. We have tapped into the enormous power of mother nature and may have to wait until the well runs dry before we see see the end of this disaster.

    June 16, 2010 at 4:17 am | Report abuse |
    • Troy

      Mark all that is needed is common sense to figure the flow. Thanks for you analysis. The other common sense thing we need is a complete assault on the mess which includes unlimited budget and get everything possible thrown at it.

      June 16, 2010 at 5:09 pm | Report abuse |
    • John

      I did similar calculations the day I first saw that 30 sec clip– even eyeballing it you could see that 21 inch pipe was gushing at least a barrel/second. Now, how could BP engineers ever hope to solve this problem if they actually thought it was four barrels per minute. There's no way these guys are that dumb.

      June 16, 2010 at 5:17 pm | Report abuse |
    • nanobot

      Here's another way to see if your estimate sounds reasonable. I have heard that other deep water wells in the area near the Horizon have flow at 70-135 barrels per day, and these are with chokes on (up to 567 mil gallon per day). They are probably tapping the same reserve at similiar pressures and depth. BP had to know that, and they believed this was going to be their best producing well. For them to come out when the riser is practically wide open and give this low ball 5,000 barrels a day song and dance had to be a blatant criminal lie. What is really sad is that everybody fell for it, because you could plainly see more than 3.5 barrels a minute coming out of that 20" pipe.

      June 17, 2010 at 2:54 am | Report abuse |
    • davec

      The oil pressure is 26,000 psi. Remember that the oil is more viscous than the water in your garden hose. Additionally the oil is flowing out into water that is more viscous than the air you garden hose sprays into.

      June 17, 2010 at 6:02 pm | Report abuse |
    • Bob

      It's all moot: I have it from reliable sources BP is trying to get a hold of Professor Peabody and his Wayback Machine.

      June 17, 2010 at 6:04 pm | Report abuse |
  2. Texas Pete

    Mark, your calcs are wrong for the following reasons, some leading you to overestimate, some to underestimate.

    1. The outside diameter of that pipe is 20", the inside is about 4-5"
    2. The pressure in the pipe is around 9000 psi, but there is about 2200 psi pushing back from the water
    3. The viscosity of oil is not very similar to the viscosity of water
    4. A large amount of natural gas is coming out with the oil.

    June 16, 2010 at 5:23 pm | Report abuse |
    • Darrell

      Texas Pete your calculations are incorrect. The pipe riser pipe is a bit over 19.5 inches Inside Diameter. 6800 PSI differential at the cut-off would produce a liquid velocity in excess of 50 feet per second and a liquid flow rate of better than 10 Barrels a second. Using water or crude specs changes the spill rate very little. The Natural Gas is still in liquid form and making an effort to split the spill into it's separate contents is an effort to make the spill look less serious than it really is. The fact of the matter is between 2 and 5 Barrels a second are coming out of the well. The exit speed is greater than 5.5 feet per second and that equals 170,000 BARRELS PER DAY at LEAST any way you cut it. Also keep in mind that the stuff coming out of the well is HIGHLY COMPRESSED by at least a factor of 2 compared to what it will be when it hits the surface (not counting the Natural Gas).. Senior Piping Designer from Texas.

      June 16, 2010 at 5:36 pm | Report abuse |
    • Mark

      Hi Pete. Of course my calculations are wrong. I'm not an engineer and I'm not a mile deep in the gulf with a flow meter, however what I do offer is a simple but logical opinion. Also, the inside diameter of the riser is very close to 20 inches, please check your sources. According to your statement you claim that the pressure of the well is 9000psi and the force of the mile of ocean pushing down is 2200psi, doing the math here tells me that the pressure of the oil leaving the wellhead is 6800psi, that number far exceeds my estimate of the leak. Your opinion is appreciated and thanks for responding to my post.

      June 16, 2010 at 6:36 pm | Report abuse |
    • nanobot

      Can anyone tell me the volume change of methane from 2200 psi to sea level? BP is reporting cu ft of methane collected and barrels of crude. If we could convert the cu ft of methane at sea level to the volume at depth we could easily determine the fraction volume which is oil. Also, does anyone here notice on the high res video of the cut riser, there seems to be a delamination of the pipe? The inner pipe has become restricted, which is where the darker flow is (oil) and the separation of the two pipes (internal and external) is where the lighter (methane) is concentrated. Isn't this a very bad sign? The pipe is essentially dissected and what are the ramifications of that regarding the bed rock stability? Any ideas?

      June 17, 2010 at 3:02 am | Report abuse |
  3. jpl89

    Their are a number of problems with your estimate. The flow orifice is not a circular 20 inch pipe, the pipe is smashed, so its area is much less than the nominal inside area of the pipe. So not only is there less area, the edge is sharp which affects the discharge coefficient. And finally, you cannot scale flow problems, they are nonlinear. All these things will cause you to significantly overestimate the flow rate.

    Perhaps some things are best left to experts after all, although I wouldn't trust BP's numbers becuase they have every reason to downplay the scale of the disaster.

    June 16, 2010 at 5:28 pm | Report abuse |
    • eric

      this world is crazy

      June 17, 2010 at 4:59 pm | Report abuse |
  4. Will

    Linda: Jive talk? Wow, you are a racist

    June 16, 2010 at 5:31 pm | Report abuse |
    • Todd

      Or a Bee Gees fan.

      June 17, 2010 at 10:06 am | Report abuse |
  5. Edward Hayes

    Use nature's own calcium deposits like white blood cells and make a wire bandage around the leak win which the calcium can grow on and stop the leak quickly, naturally, and completely.

    June 16, 2010 at 5:44 pm | Report abuse |
    • vt-er

      I dont think BP would do that. This well is a cash cow whether it is leaking throughout the gulf or not. Why else would they have put all their focus in the early days of this disaster on containing the spilled oil and not on shutting down the well. They knew it would be permanent. Greedy fu@#$, the whole lot of em.

      June 17, 2010 at 5:01 pm | Report abuse |
  6. GW

    A quick calculation of the volume of the slick a week into this (150x30miles by 0.1 inch average depth) shows that at least 2.5M gallons a day were being released. And this estimate doesn't account for oil in solution due to use of dispersant.

    June 16, 2010 at 5:49 pm | Report abuse |
    • Bob

      Measuring the spill volume by calculating surface slick area is ludicrous when you have access to the source. Can you accurately tell how many gallons of water you have put on your lawn by measuring the area and guessing how deep the water goes?
      Why bother doing that if you can calculate the flow rate out of the hose?

      June 16, 2010 at 10:15 pm | Report abuse |
  7. Joshua

    It's 162,000 barrels a day or more. I know because BP itself said that would be the "worst case scenario" when the filed the permit for the well. This is DEFINITELY "worst case scenario"

    June 16, 2010 at 6:17 pm | Report abuse |
    • Laura

      Good point. I bet you are right, and hope you are wrong.

      June 16, 2010 at 7:32 pm | Report abuse |
    • nanobot

      Since wells in the area are known to produce 135k barrels per day with chokes on, that sounds very realistic.

      June 17, 2010 at 3:05 am | Report abuse |
  8. floydfix69

    a least 4 barrels a sec but the cracks around it in ocean floor doesn't look good. too new well tap's the pool and stops the pressure.

    June 16, 2010 at 6:22 pm | Report abuse |
  9. Jay Alt

    Notes on how the 'Official' Govt announced rates were arrived at:

    April 24 estimate 1,000 bpd was made from oil observed by CG ships at the drill site.
    April 28 (5,000) an NOAA estimate – method unknown to me. This number was not picked up by many media, who continued to use the 1,000 bpd untile SkyTruth hired an oceangrapher to analyze satellite photos in early May. His estimate was more than 25,000 bpd, based on satellites.

    May 27 estimate (12,000 – 17,000 bpd) again – NOAA scientists qualified them as surface observations, no reporters stressed this fact.
    June 14 estimate (25 – 60,000 bpd) estmate finally includes subsea video, pressure guages, collection rates, etc

    There waw tests on a deepsea test done in the North Sea in the 1990s. It showed that a deep high-pressure leak would form a mousse-like emulsion that would stay underwater. BP helped fund this test and their engineers would have known this result and threat.

    If BP had not withhold the ROV video for 3+ weeks, NOAA would have realized the scope of the spill alot sooner.
    Because even retired oilmen who saw the first May 13 ROV video said it was clear the rate was far higher than 5,000 bpd.

    June 16, 2010 at 6:33 pm | Report abuse |
    • nanobot

      Good to know about the North Sea testing, meaning that NOAA estimates would be low, and BP was fully aware of that. Also, the delay in releasing video had a critical impact in assessing the problem and the response. We never had a chance to get ahead of it with that delay.

      June 17, 2010 at 3:10 am | Report abuse |
  10. xlr8r

    Don't believe the figures released by BP or the gov. They are trying to downplay the scale of this , each for their own reason. The government's own estimate of 5,000 bbl/day came from NOAA's Seattle office. It is total BS. Go read Rolling Stone's piece on this. http://www.rollingstone.com/politics/news/17390/111965 They have a photo taken in the Seattle NOAA office the day of the explosion. It is the white board in their "war room". Clearly written on the board is the following: "estimate 64k – 110k bbls/day". As far as I know, NO JOURNALIST has asked about this huge discrepancy. BP's environmental impact statement states the worst case scenario is over 140,000 bbls/day. Isn't it incredibly obvious to all why BP refused to let anyone adequately measure this? Now that the pipe has been cut they can claim whatever they want for the volume prior to the cut since there are no actual metrics.

    June 16, 2010 at 6:40 pm | Report abuse |
  11. xlr8r

    Also note that the government only released the low end flow estimate flow estimate generated by their scientists. One of them spoke out on his own telling the media that the likely flow rate was significantly higher.

    June 16, 2010 at 6:48 pm | Report abuse |
  12. almxx

    This oil surge show the immense amount of oil that really exists. The earth is full of self regenerating oil that is probably formed by the reaction of the internal heat of earth acting on whatever mineral, etc. are there. There is no shortage of oil, obviously, because you can have as much as you can pay for. The oil companies will now have to cut back on oil production, so as not to have a glut on the market. They will gauge their production to not have an excess, because there is no place left to store it. President Carter should be recognized as the great prophet he was, and Reagan for the billionaire's puppet that he was.

    June 16, 2010 at 7:18 pm | Report abuse |
    • MB

      You know, it's not hard to look up how oil is formed, and it's far from limitless.

      June 17, 2010 at 1:09 am | Report abuse |
    • T-Bone

      Very scary that people don't even know the basics about oil.

      June 17, 2010 at 11:07 am | Report abuse |
    • dg

      Almxx has a point. The theory that hydrocarbons were created by a decaying biomass was plausible before geologists discovered just how vast the supplies of oil, gas, and coal really are, along with the discovery of methane on other planets.

      June 17, 2010 at 5:14 pm | Report abuse |
  13. Paul

    Let me represent the tea baggers here... why the hell is the government involved in the clean up? That's communism, rawrrr!!!

    June 16, 2010 at 7:28 pm | Report abuse |
    • nanobot

      LOL, I actually think these super mega corporations are the new communists, even though they are capitalists. They own the government, they own the media. It's not the government communists we have to worry about it's the corporate communists. They control everything. They are TOO BIG.

      June 17, 2010 at 3:16 am | Report abuse |
    • spiffypants

      Nono: It's Corporatism. Both political parties are guilty of this. Dems want to blame the Repubs, Repubs want to blame the Dems. But it's all a game so 'We the People' blame what ever party we claim not to be. It works well for them.


      June 17, 2010 at 5:52 pm | Report abuse |
  14. Dr. Anthony Hayward

    Hey gais! Why does the peeeple in the US of A be so meen 2 me? I only try to give gas at prices discounted before taxes to you. We can never no the spill amount becaz peeple in the gulf keeps taking our money becaz they say we destroys the fishes that they like to eat. We spend much too money paying peeple in the gulf who should have jobs anyways. The spill is too deep for us to see well since cameras don't werk well underneath all that water and so we know that problem isn't bad because it is dark too much down there. So please peeple of amereeca, stop tryeeng to gess the speel. I just want my life back to the way it was when I lived in the great britan and didn't have to theenk about all of this. Anyways, tank yew for leting us drill in your watur. We promise that da speel will eventually go away becaz the oshen is a biggest place. We weesh we could stay longur but your leader Baraky someting-bama want us tew leave. Gud lcuk wtih a realy small speel, you gais should have it dun in know tym. KKTHXBAI!

    June 16, 2010 at 8:29 pm | Report abuse |
  15. Anton K

    Regulations were in place were partly unenforced as of... Hussein Obama signed for more oil until... Contain, clean up and the blame 'game' needs to end although it took him months to get serious.

    1) **A rubber cork**
    2) Inflatable Nano material.
    3) Future blow out preventers need to have more safeties given money printing ...***AND**.. birth control.
    4) More oil leaks off the coast of Nigeria ever year as of...

    June 16, 2010 at 8:59 pm | Report abuse |
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