Gulf Oil Spill Velocimetry-Based Flow Rate Estimate

[83729780]

What is the maximum output of the well?

It's been said in numerous places that no well in the gulf produces more than 40 thousand barrels per day. Werely's original estimate gave a range of 56 to 84 thousand barrels. Mind you, the well is far from unobstructed, and he reached that estimate by observing one point of effluence.

Without further calculation, is it safe to assume that his original estimate was quite high?
edit: http://www.theoildrum.com/node/6489#comment-626528

In Congressional testimony BP mentioned a maximum rate of 60,000 bpd but I believe the phrasing of the question (conveniently eliminated by most of the media) was what was the theoretical absolute maximum rate of flow if the well was totally unrestricted - no BOP, no downhole obstructions, etc. I think in later testimony they reduced that to a maximum of 55,000 bpd.

Historically the largest completely open well gushers have all maxed out at about 100,000 bpd and usually dropped off within a few days. The Lakeview gusher (California 1910) was estimated to reach 100,000 bpd, ran unchecked for 18 months, but over that time "only" averaged between 15,000 and 20,000 bpd.

Gulf of Mexico wells have never been capable of delivering the flow rates of the largest onshore wells in the Middle East, Texas or California. The maximum perforated and controlled flow rates have been about 40,000 bpd so it kind of requires a suspension of reality when people outside the industry start talking about flow rates of 70,000 to 100,000 bpd (and higher) through a well that does have restrictions. Even if the well was totally unrestricted, ie: no pressure reduction in the BOP, it is unlikely the well is physically capable of producing over 60,000 bpd.

 

[mheslep]

USGS announced the flow rate results today of their study groups: 12,000 to 25,000 bbl/day.
http://www.nasdaq.com/aspx/stock-ma...udy-team-calculated-12000-b/d-19000-b/d-range

 

[stewartcs]

I'm still not clear on the correct size of the pipe. I've heard 21" and 9". Do we have a good indication anywhere on which it really is?

Russ,

The riser has an OD of 21". The ID is dependent on the wall thickness. If memory serves me correctly it should be 3/4" walled riser on those slick joints that connect to the riser adapter so the ID would be 19.5".

CS

 

[stewartcs]

I've found a copy of a ppt presentation Wereley gave on the subject, on the US House website. http://energycommerce.house.gov/documents/20100519/Wereley.Presentation.05.19.2010.pdf

Of note:
-He used a single, 15fps internet video for his analysis.
-He matched features and counted pixels, apparently manually, from one frame to the next.
-He scaled based on the 21" shaft size (not the 9" riser size).

Based on his ppt presentation, his method - as I speculated before - bears only superficial resemblance to PIV and really isn't any more sophisticated than any armchair observer could do. There ws no special skill involved in this estimate.

Also, another potential source of error I didn't think of before but can see in his ppt presentation:
10. Buoyancy of oil and gas provides an upward component of velocity immediately after leaving the pipe.

I agree with you Russ.

Presuming he could actually identify the particles correctly (which I doubt since he has no tracer particles injected) his calc is still wrong due to the wrong diameter of pipe used. The nominal ID is 19.5-in (he used 20-in), however, no one is certain how much actual flow area there is available. If it drops to an effective ID of 3-in then the flow is severely diminished by his own methods to about ~1600 BPD.

CS

 

[mheslep]

There are known obstructions inside the pipe, namely some kind of other smaller diameter pipe that ended up there as part of the accident or attempted remedy. Anyway, there's no reason to bother with Wereley any more as the USGS groups released figures (12k to 25k bbl/day) based on several methods (sea floor video, surface inspection, etc) and they're all in rough agreement.

 

[stewartcs]

There are known obstructions inside the pipe, namely some kind of other smaller diameter pipe that ended up there as part of the accident or attempted remedy. Anyway, there's no reason to bother with Wereley any more as the USGS groups released figures (12k to 25k bbl/day) based on several methods (sea floor video, surface inspection, etc) and they're all in rough agreement.

Yes, there is a 5-in drill pipe inside of the stack and riser.

I never really bothered with Wereley anyway and I certainly don't believe the other estimates from any other groups...yet.

CS

 

[mheslep]

[...] I certainly don't believe the other estimates from any other groups...yet.

CS

I listened to the breakdown of the methods as described by the USGS chief - they hit all the logical steps, and their estimates don't exceed the daily rate of other working rigs, a good sanity check.

 

[stewartcs]

I listened to the breakdown of the methods as described by the USGS chief - they hit all the logical steps, and their estimates don't exceed the daily rate of other working rigs, a good sanity check.

I've not heard any of the specifics regarding their estimates yet but I look forward to hearing them.

I wouldn't expect their estimates to exceed a producing well. Producing wells can flow up to 200,000 barrels per day IIRC depending on the formation/reservoir.

CS

 

[mheslep]

I've not heard any of the specifics regarding their estimates yet but I look forward to hearing them.

I wouldn't expect their estimates to exceed a producing well. Producing wells can flow up to 200,000 barrels per day IIRC depending on the formation/reservoir.

CS

The limit on deep water wells in that that area is about 30,000 bbl/d according petroleum engineers interviewed.

 

[mheslep]

I've not heard any of the specifics regarding their estimates yet but I look forward to hearing them.

USGS Director Dr. Marcia McNutt today. They used three approaches: surface satellite observation (12k - 19k), sea floor plume observation (12k-25k), and RITT observation (11k).
http://www.2theadvocate.com/news/95030444.html

 

[stewartcs]

The limit on deep water wells in that that area is about 30,000 bbl/d according petroleum engineers interviewed.

I'm not sure what they are currently pumping but most of the big platforms can pump 200,000 to 250,000 BPD.

Do you have a reference for the 30,000 BPD by chance?

CS

 

[mheslep]

I'm not sure what they are currently pumping but most of the big platforms can pump 200,000 to 250,000 BPD.

Yes, but I believe those figures represent multiple wells under the same platform as at BP's 250k bbl/day http://www.offshore-technology.com/projects/crazy_horse/" platform in the Gulf:

The development consists of 25 wet-tree subsea wells tied into a floating platform.
[...]
The facility is designed to process 250,000b/d of oil and 200mmcf/d of gas per day.

Do you have a reference for the 30,000 BPD by chance?

http://www.chron.com/disp/story.mpl/business/deepwaterhorizon/7011584.html

More than half a dozen industry professionals who test wells flow and study oil formations were skeptical in interviews about estimates as high as 80,000 barrels a day, given the production rates of nearby deep water wells that yield 15,000 to 30,000 barrels a day.

“We work hard to maximize flow rates in deep-water wells and I don't know any well in the Gulf of Mexico that made that kind of rate,” said Stuart Filler, president of the Society of Petroleum Evaluation Engineers

 

[alexhiggins]

I see that you there is great criticism of Steve Wereley's estimates but two other scientists also gave estimates of 20,000 - 100,000 BPD.

Yet, there has been no criticism of the USGS calculations.

Being a layman I have many criticisms of my own and would like to get input on the from the real scientists...
[link deleted]

 

[jreelawg]

I don't know what to make of any of the estimates. When S.W. made his initial estimate, at the time, all he had to go by was a short video clip showing only one out of several leaks. He made it clear in one interview that this was not an estimate of how much oil is leaking into the gulf, just an estimate, of how much material was flowing out of this particular leak, during the time of that 25 second video clip. Of coarse, I didn't hear him address the aspect of composition. That particular video clip, to me, looked like it was leaking more natural gas then any of the footage I've seen since. With a constant change in composition, I think it would be hard to estimate the flow based on 25 seconds. My thought is that BP must have released a clip showing a natural gas pocket discharging. At the time and prior to releasing the footage, they were reporting that because this well is leaking natural gas as well, it is leaking less oil. So I imagine they probably released a clip trying to give credence to that statement.

Other estimates since, I have not seen any of the details of their specific methods. Are they taking into account the massive amounts of dispersants being applied directly on the leak a mile below?

 

[jreelawg]

I'm not sure what they are currently pumping but most of the big platforms can pump 200,000 to 250,000 BPD.

Do you have a reference for the 30,000 BPD by chance?

CS

On C-span it was revealed that the worst case leak for this well, was estimated at 250,000 barrels per day. This was prior to the accident. This was the number written into the documentation required for BP to get the permit. The significance of this number, is that it is the intensity of the leak possible, and BP was required to have the capability to hand this in a worst case scenario.

 

[russ_watters]

On C-span it was revealed that the worst case leak for this well, was estimated at 250,000 barrels per day. This was prior to the accident. This was the number written into the documentation required for BP to get the permit. The significance of this number, is that it is the intensity of the leak possible, and BP was required to have the capability to hand this in a worst case scenario.

Typically, when designing for such a contingency, the criteria is far beyond the worst case that can be imagined. Ie, the parts of a bridge might use a safety factor of 250%.

 

[alexhiggins]

Why was the link to my criticisms deleted?

 

[mheslep]

Why was the link to my criticisms deleted?

I don't know, but the guidelines (which you agreed to upon joining PF) apply in an Engineering forum:

Overly Speculative Posts:
One of the main goals of PF is to help students learn the current status of physics as practiced by the scientific community; accordingly, Physicsforums.com strives to maintain high standards of academic integrity. There are many open questions in physics, and we welcome discussion on those subjects provided the discussion remains intellectually sound. It is against our Posting Guidelines to discuss, in most of the PF forums or in blogs, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion. Personal theories/Independent Research may be submitted to our Independent Research Forum, provided they meet our Independent Research Guidelines; Personal theories posted elsewhere will be deleted. Poorly formulated personal theories, unfounded challenges of mainstream science, and overt crackpottery will not be tolerated anywhere on the site. Linking to obviously "crank" or "crackpot" sites is prohibited

https://www.physicsforums.com/showthread.php?t=5374

 

[mheslep]

On C-span it was revealed that the worst case leak for this well, was estimated at 250,000 barrels per day. This was prior to the accident. This was the number written into the documentation required for BP to get the permit. The significance of this number, is that it is the intensity of the leak possible, and BP was required to have the capability to hand this in a worst case scenario.

I doubt a number that high could have been used by knowledgeable engineers or scientists. Would you have a print source for any of this?

 

[jreelawg]

I doubt a number that high could have been used by knowledgeable engineers or scientists. Would you have a print source for any of this?

"Such a blowout could have spewed 250,000 barrels a day, according to the 582-page plan."

http://www.businessweek.com/news/2010-05-31/bp-ready-for-spill-10-times-gulf-disaster-plan-says-update1-.html

 

[mheslep]

"Such a blowout could have spewed 250,000 barrels a day, according to the 582-page plan."

http://www.businessweek.com/news/2010-05-31/bp-ready-for-spill-10-times-gulf-disaster-plan-says-update1-.html

Thank you. Interesting, I'd like to see the permit BW refers to. Google's not turning it up.

 

[stewartcs]

"Such a blowout could have spewed 250,000 barrels a day, according to the 582-page plan."

http://www.businessweek.com/news/2010-05-31/bp-ready-for-spill-10-times-gulf-disaster-plan-says-update1-.html

Buiness Week is hardly a reputable source. I believe they have taken that number out of context. Perhaps it was referring to the maximum production capability of a platform in that block of water.

CS

 

[mheslep]

Buiness Week is hardly a reputable source. I believe they have taken that number out of context. Perhaps it was referring to the maximum production capability of a platform in that block of water.

CS

That makes sense - if an entire multi-well mega platform suffered an uncontrollable fire then in a theoretical worst case the total platform output could be spilled, and I could see a permit application having to address that scenario. Stating that a single well could release at that rate (250k bbl/day), from this geography, does not make sense.

 

[jreelawg]

That makes sense - if an entire multi-well mega platform suffered an uncontrollable fire then in a theoretical worst case the total platform output could be spilled, and I could see a permit application having to address that scenario. Stating that a single well could release at that rate (250k bbl/day), from this geography, does not make sense.

I googled "multi-well mega platform" and got no results.

 

[mheslep]

I googled "multi-well mega platform" and got no results.

My 'mega' hyperbole probably throws it off. See e.g. http://www.offshore-technology.com/projects/crazy_horse/ which is actually the Miss. Canyon area of the Gulf referred to in the permit.