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Oil Spill Insights from a Retired Manager of an Offshore Underwater Service Company
The Oil Drum ^ | May 8, 2010 - 10:40am | Gail the Actuary

Posted on 05/10/2010 10:51:02 AM PDT by Ernest_at_the_Beach

This is a guest post from Oil Drum commenter shelburn, who is a retired manager for an offshore underwater service company.

I have been reading the various reports from the media for the last few days and am distressed by the amount of misinformation that is being provided to the public. In response, I have put together some rough calculations and have tried to develop analogies that are understandable to laymen regarding what has happened and what is/can be done.

I have some relevant background, as I was in the offshore industry, primarily in the underwater service side for many years, so I am familiar with diving and ROV operations. I have also been involved in designing and building an oil capture and recovery dome (actually a pyramid) in much shallower water. I also was involved in the Exxon Valdez cleanup and environmental surveys, several years after that incident, among other things.

I’m not a downhole expert, so I’ll leave that side to Rockman and others with the necessary training and experience.

The Leaks:

There is every indication that the Blowout Preventer (BOP) was activated and at least partially worked. There is a good probability that the “leak” is inside the BOP. As the oil leaks through the BOP, it then finds its way through the damaged riser and drill pipe, where it will exit from any open end or damaged area.

Therefore trying to repair the leaks in the riser does not decrease the flow, but it can reduce the number of places where oil must be captured--which is why they capped the end of the leaking drill pipe. If a company tried to stop all the leaks coming from the riser, it would probably be like trying to repair a rotten garden hose. Every time the company stopped one leak, another one would appear. The task is to try to reduce the leaks to one, or to a couple in the same area, so the containment dome can be put over them and the oil recovered while waiting for the relief wells to "kill" the well.

Every deepwater work class Remotely Operated Vehicle (ROV) carries sector scan sonar. Sonar can pick up oil leaks that the naked eye cannot see. The picture of oil bubbles painted on a sonar screen looks like fireworks going off.

There was an ROV survey of the BOP and riser within hours after the rig sank. At that time, there was no indication of any oil leakage from the BOP, and everyone breathed an extremely large, and extremely premature, sigh of relief.

Estimates made about leakage are primarily done from aerial surveys and satellite photos These are notoriously inaccurate, as is clearly stated in the USCG manual on reporting oil spills. The gravity and thickness of the oil, temperature, weather, currents, time, weathering of the oil and other factors all have a major impact on the size of a slick from a given amount of oil.

For example, if you are on a lake in very still water and pour a gallon--not a barrel, a gallon--of gasoline over the side, in a matter of minutes you can have a slick covering a square mile. If you want to try this, pick a cool day as on a warm day the gasoline will evaporate before the slick finishes forming. Also, the Coast Guard would be most unhappy if it knew you were attempting this experiment.

If you do the same with heavy crude similar to what was involved in the Exxon Valdez spill, it will probably take a few hundred barrels to cover that same square mile. Over a long enough time period, though, the type of oil involved in the Exxon Valdez spill will end up covering an area many times larger, and will take months to dissipate in the absence of heavy weather. The sweet crude involved in this spill is somewhere in between.

It was sometime during the night after the sinking that oil leaks started appearing from buckles and holes in the riser. This was stated to be about 1,000 barrels per day. I would read that to mean the leak was between 250 and 3,000 barrels per day (bpd). And a 5,000 bpd leak is probably between 2,000 and 10,000 bpd. Until there is some way to measure the flow--like running it through a pipeline or into a tank--it is impossible to have any accurate measurement of the leakage.

Factoid: If you assume that there is over 5,000 psi of downhole pressure at the BOP--and everything I have heard indicates it is probably substantially higher than that--then a 1/4 inch diameter hole is large enough to “leak” 5,000 barrels a day. That “leak” would probably cut off your arm if you passed it in front of it.

There is almost certainly sand in the oil. As that sand passes the leaking portion of the BOP, it acts as an extremely high pressure sand blaster, eroding the area around the leak and enlarging the hole. So there is a perfectly rational explanation why the leak would escalate from 1,000 bpd to 5,000 bpd to whatever it is now.

Nobody was lying about the volume or covering up. The leak was, and is, getting worse.

How much is 1,000 bpd? It works out to 30 gallons per minute, about the output from 3 garden hoses running wide open, or about enough to fill a smallish backyard swimming pool in 24 hours.

Weather

I’m not an oil spill expert, so I won’t address the clean up much except to mention the effect weather has on it.

For actually recovering the oil, calm weather is the best. It only takes about 3 or 4 foot waves to greatly impede skimming operations and render inflatable booms ineffective.

Unfortunately, the first week of the spill had enough bad weather that recovery operations were slowed and actually stopped for a few days. This week things have been much better, and a lot of oil, but certainly not all, has been recovered before it reached land.

The most effective spill cleanup is a violent storm. Mother Nature is much more successful than man at taking care of herself. In Alaska, we found areas prone to heavy storms were essentially clean after one winter, while protected bays and inlets still have oil deposits more than 20 years later.

A number of years ago, a small tanker with a full load of fuel broke up on the Scottish coast during a North Sea winter storm. Heroic efforts by the British Coast Guard and the salvage tug crew saved most of the crew members, but the tanker was completely destroyed, and all the cargo spilled. There was a great fear of massive environmental consequences. But after the storm abated, there was almost no sign of the oil. The power of the storm had effectively dispersed all the oil and cleaned the rock beaches and cliffs.

Obviously the answer is to recover the oil before it reaches land, but a large storm that pushed the oil out to sea and broke it up would be beneficial. That is unlikely to happen at this time of year. It is much more likely any storm would push the oil onshore and would not be violent enough to disperse it.

Remotely Operated Vehicles (ROVs)



TOPICS: Business/Economy; Conspiracy
KEYWORDS: energy; oilspill
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To: Ernest_at_the_Beach

It must be damn cold down there. Interesting. I don’t recall any articles quoting the sea floor temp of the water in this area.


21 posted on 05/10/2010 1:27:49 PM PDT by Marine_Uncle (Honor must be earned....)
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To: Marine_Uncle

Somewhere I recall 1 degree C is the temp.


22 posted on 05/10/2010 1:35:31 PM PDT by Ernest_at_the_Beach ( Support Geert Wilders)
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To: Ernest_at_the_Beach

So where almost at zero degrees. 1.8F. A bit colder then I would have suspected. We need some global warming “hidden heat in the oceans” to quickly warm things up for the BP folks.


23 posted on 05/10/2010 1:51:49 PM PDT by Marine_Uncle (Honor must be earned....)
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To: patton

The venturi effect.
http://en.wikipedia.org/wiki/Venturi_effect


24 posted on 05/10/2010 2:00:42 PM PDT by Deaf Smith (When a Texan takes his chances, you know chances will be taken that's for sure.)
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To: Ernest_at_the_Beach

I have a buddy who has an idea I think would work to stop the leak. He built a prototype this morning, and it works great. We just can’t figure out who to pitch it to.


25 posted on 05/10/2010 2:11:08 PM PDT by genetic homophobe
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To: Deaf Smith

http://en.wikipedia.org/wiki/Bernoulli%27s_principle


26 posted on 05/10/2010 2:20:03 PM PDT by patton (Obama has replaced "Res Publica" with "Quod licet Jovi non licet bovi.")
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To: patton

Yes.


27 posted on 05/10/2010 2:25:17 PM PDT by mad_as_he$$ (If you can read this you are the resistance.)
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To: mad_as_he$$

Hey, no fair going all laconic on me!


28 posted on 05/10/2010 2:27:08 PM PDT by patton (Obama has replaced "Res Publica" with "Quod licet Jovi non licet bovi.")
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To: Ernest_at_the_Beach
Gulf Oil Spill A Geoint Community
29 posted on 05/10/2010 2:28:30 PM PDT by bmwcyle (Thank You God for Freeing the Navy Seals)
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To: patton
The end result is still the removal of heat from the low pressure containment dome?
30 posted on 05/10/2010 2:58:05 PM PDT by Deaf Smith (When a Texan takes his chances, you know chances will be taken that's for sure.)
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To: Ernest_at_the_Beach

Why wouldn’t this idea work: Take a piece of small diameter pipe (say 1” or smaller). I’m assuming the pipe leaking the oil is not much bigger than 10”. Put an air fitting on the top end of the small pipe. Along the pipe, drill a small hole in the side. Clamp a bladder around the small pipe (a section of heavy duty balloon tubing, maybe made from the stuff the balloons were made of to float the 767 up from the Hudson), above and below the small hole drilled in the side. You could do this 2 or three times, depending on the length of pipe. Run compressed air (or compresses whatever)to the fitting at top of small pipe. Insert the small pipe down into the leaking riser, and send the air into the small pipe. The bladders inflate, sealing the riser, and all the pressure is going out against the leaking pipe. We made a prototype this morning with a half inch piece of copper pipe, drilled a hole in the side, clamped a piece of rubber inner tube above and below the drilled hole. Then we pumped water through a 6” piece of PVC pipe. When we stuck the copper pipe in and put the air to it, it immediately sealed up the pipe, totally. We could carry around the water filled PVC pipe by the copper one, no leaks. What’s wrong with this idea?


31 posted on 05/10/2010 3:02:33 PM PDT by genetic homophobe
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To: genetic homophobe

The well casing is 20” diameter and twisted like a pretzel. Plus the well was reported to be a 40,000 psi formation.


32 posted on 05/10/2010 3:07:13 PM PDT by mad_as_he$$ (If you can read this you are the resistance.)
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To: mad_as_he$$

Well it doesn’t look like much pressure pushing oil out of the casing, no doubt due to the tremendous water pressure at that depth. You wouldn’t need it to be straight. You could push the smaller pipe through the leaking oil and inflate it.


33 posted on 05/10/2010 3:18:52 PM PDT by genetic homophobe
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To: Ernest_at_the_Beach; AdmSmith; Berosus; bigheadfred; Convert from ECUSA; dervish; Fred Nerks; ...

Thanks Ernest_at_the_Beach.


34 posted on 05/10/2010 3:35:56 PM PDT by SunkenCiv ("Fools learn from experience. I prefer to learn from the experience of others." -- Otto von Bismarck)
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To: Deaf Smith

Evaporation is a heat-losing process.

Dump alcohol on your hand, your hand will get cold, as it evaporates off.

Swimming pools in AZ are FREEZING cold, because the water evaporates off so fast.

So, if you offgass methane hydrates fast enough, you can freeze anything.

I am beginning to suspect that is what went wrong - they tapped into a high-pressure methane reserve, and when it blew - low pressure. So evaporation, just like in a fridge.

Or, by reducing the pressure on frozen methane, they could have caused it to boil over - causing a big blow.

Remember, the freezing point is not fixed. It depends entirely on pressure (think cake recipes in Denver).

Note - I am not an oil-driller guy. Just reading what gets reported.


35 posted on 05/10/2010 5:50:19 PM PDT by patton (Obama has replaced "Res Publica" with "Quod licet Jovi non licet bovi.")
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To: genetic homophobe

Try pitching it at the link below.

Horizonsupport@oegllc.com


36 posted on 05/12/2010 5:55:46 PM PDT by Bigun ("It is difficult to free fools from the chains they revere." Voltaire)
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To: Bigun

Who’s email address is that?


37 posted on 05/12/2010 7:05:11 PM PDT by genetic homophobe
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To: genetic homophobe

That is the address for BP’s Deepwater Horizon suggestion box.


38 posted on 05/12/2010 7:29:26 PM PDT by Bigun ("It is difficult to free fools from the chains they revere." Voltaire)
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To: Bigun

Will do, thanks


39 posted on 05/12/2010 9:04:43 PM PDT by genetic homophobe
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