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Jun. 6 2010 - 1:45 pm | 866 views | 0 recommendations | 9 comments

The X factor: Measuring BP’s oil spill progress

Cap, Saturday June 5

It’s like using a kitchen scale to weigh adults and concluding that the average person weighs somewhere between zero and ten pounds.

“That operation has gone extremely well. We are very pleased.”

That was BP VP Bob Fryar’s assessment yesterday of his company’s success in capturing some of the oil gushing from its wild well on the bottom of the Gulf of Mexico.

On Friday, we said that the cap seemed headed for failure. So who’s right?

As usual, it gets down to how you define “success” and “failure” (and on how you do the math).

Downsizing the Mission

Photo: Coast Guard

First, it’s important to note that BP has moved the goal posts after the process known as “Top Kill” failed. Actually, it’s more like they started playing a different game altogether, and they managed to did it without drawing media attention. Top Kill was the last in a long line of attempts to shut the well down — as the word “kill” implies. BP’s new game is designed, at best, to divert a portion of the oil up a pipe to the surface. Killing the well won’t be accomplished until relief wells tap into the existing pipe far below the ocean floor and inject cement there. BP has said that will take until August. (Some experts believe it will take longer, perhaps an additional six months.)

“Containing” the oil using the cap is much more manageable. Then again, maybe not. Yesterday, BP’s Doug Suttles was optimistic that the cap would ultimately bring over 90 percent of the oil to the surface where it would be pumped into a tanker. To get anywhere near that figure, four vents on the cap need to be closed, a job that was supposed to happen on Friday.

Oil Continues to Threaten Coastal Wildlife

Photo: Matthew Hinton, The Times-Picayune

At a Saturday morning press conference, however, Coast Guard Adm. Thad Allen confirmed that all of the vents remained open, for fear of increasing the pressure on the cap too quickly, causing it to malfunction or break apart. On Sunday, it appears that all vents remain open.

Even so, BP reports today that they have succeeded in bringing up 10,500 barrels of oil in the last 24 hours, a figure they say represents over half of the 19,000 barrels the government estimates is leaking each day.

BP’s Kinky Math

There are some problems with these numbers.

First, the 10,500 barrels can’t simply be subtracted from the estimated flow at the wellhead. The flow was from a smaller opening in a pipe narrowed by a kink. As they moved from killing the well to containing the oil, BP said that the flow would increase by an estimated 20 percent. Anyone watching one of the live cams noticed a surge in the volume of oil after the cut was made. So, if their estimates are correct, by the time the cap was put in place the flow had increased by 3,800 barrels per day.

Which means BP’ has reduced the amount of oil flowing into the Gulf by 6,700 barrels per day.

But even that overstates the success of the current effort.

Before Top Kill, BP had started a very low-tech process: siphoning oil through a six-inch tube stuck into the broken riser. The amount of oil “contained” by that tube was 2,000 barrels per day.

So, after all that BP has done since May 18th (when the tube was drawing oil), they are, as of this morning, capturing a net gain of 4,700 barrels of oil a day.

Government’s Hinky Math

After weeks of maintaining that the flow was just 5,000 barrels per day, the government dramatically upped that range. On May 27, Dr. Marcia McNutt, chair of the federal Flow Rate Technical Group, said that the range of oil being released had been upped to between 12,000 and 19,000 barrels of oil per day.

Those numbers seem as suspect as the government’s initial estimate was. First, they come from a preliminary draft report, based, in part, on low quality videos of the plume, provided by BP. The Task Force managed to pry loose a higher quality video, but the estimates based on that more accurate information won’t be released for as long as several weeks, according to McNutt.

Further, the estimates were based on the measurements of two groups of scientists. The numbers from one of the groups were estimates of the minimum amounts only. It was not possible, they concluded, to make a meaningful estimate of the maximum amount of oil spewing into the gulf.

Dr. Ira Leifer, a member of both panels (and team leader of one), has said that the government figures are “lower bound” estimates.

“It’s safe to say that the total amount is significantly larger, from some fraction to multiples of that lower bound number,” Leifer said. “I do not feel comfortable yet to provide an upper bound.”

The yardstick used to measure the percentage of oil being captured by BP isn’t a yardstick at all. It’s like using a kitchen scale to weigh adults and concluding that the average person weighs somewhere between zero and ten pounds.

At yesterday’s press conference I asked Coast Guard Adm. Thad Allen if he could clear up the misunderstandings about the range of estimates given by the government task force.

Here’s his reply:

There were two different models used to produce two different ranges. The low end is the same in both models. It’s 12,000 barrels a day. The two different models produce 12,000 to 19,000 barrels a day.

The other model produced 12,000 to 25,000 barrels a day. I don’t think it’s a bad idea to have competing models because it gives you a higher fidelity answer as you move forward. Hopefully, we’ll start moving those ranges into a more acceptable representation of what’s actually flowing.

Coast Guard Adm. Thad Allen

Allen’s answer is technically correct — but misleading. He says that the low end is the same in both models (12,000 barrels a day), but fails to mention that the estimate of 12,000 to 25,000 barrels per day shows only the group’s range of low end estimates.

So, how much of the spewing oil is BP currently capturing? IF X is the total number of barrels, then, according to the best scientific evidence available at the moment, BP is capturing X – 10,000 barrels.

The only problem is that — 47 days after the lethal failure of BP’s oil rig in the Gulf of Mexico — we still have no idea what number X represents.


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  1. collapse expand

    “To get anywhere near that figure, four vents on the cap need to be closed, a job that was supposed to happen on Friday.”

    I noted this on your last post: this was never intended to finish on Friday, but only to start, which is what happened. Production needs to be ramped up somewhat slowly to ensure that processing ships can handle it and that another leak doesn’t develop… or we might end up with your first picture all over again.

    And, the other capping methods were also attempts to contain the oil and not kill the well entirely. You can’t cap the well at the surface with a dome or something; oil and gas will find a way out. I have trouble wrapping my head around all of the science here, but I think these two points are inaccurate.

    BP says they’re capturing most of the oil and that they captured 10k barrels yesterday. Given that lying would pose serious legal consequences with the SEC etc, 12-25k/day seems as good an estimate as any.

    • collapse expand

      Hi Zach,
      In fact, now they can’t close the 4th vent because they’re not prepared to process more oil. BP’s stated goal with Top Kill was to pump cement down the well. I don’t think that part was made up. About the flow estimate – I don’t know if the 12-25K barrel range is right, just that those who came up with it didn’t believe it represented anything other than the lower range.

      In response to another comment. See in context »
      • collapse expand

        Yeah, the top kill was an attempt to permanently kill the well. I’m talking about the multiple attempts before that to insert tubes to siphon flow, the two “top hat” attempts, etc. The basic order of progress was:
        0. Start relief well drilling
        1. Try to fix the blowout preventer (not gonna happen)
        2. Stick a tube in it (failed)
        3. Try a containment dome (failed twice because of methane hydrate formation)
        4. Stick a smaller tube in it (worked, but couldn’t get much oil out)
        5. Top kill (failed because of problems down hole)
        6. Cut and install LMRP (success assuming nothing blows out before a relief well is complete)

        Anyway, only attempts 1 and 5 were trying to shut the well down. Attempt 6 is similar to attempt 3 and 3.5 in kind and not really a sea change.

        On the flow estimate, initial reports from BP and the Feds said that the maximum spill (if it were unobstructed) would be 55,000 barrels/day. Maybe I’m too naive, but this seems like it should be relatively easy to calculate.

        In response to another comment. See in context »
        • collapse expand

          You forgot my favorite: junk shot (also an attempt to kill the well).

          I don’t remember the 55,000 bpd estimate – thought it was 60K, but that’s pretty close anyway. Still, that’s three times the 19K upper limit stated by the government. I also think the calculation shouldn’t be that hard — the problem has been BP’s refusal to allow direct measurement.

          In response to another comment. See in context »
  2. collapse expand

    Mr. Davidson,

    I think the change you noted is real but different than you think it is. If they actually “kill” the well, they will have to re-drill later, which is very expensive. However, if they can “contain it”, they might still be able to recover the well without re-drilling it. If they can seal it and pump it, they have a functioning well. If they kill it, they don’t.

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