After effects

I don't understand all there is to know about underwater drilling but my question is this. What happens to the area around the well when
that said well is finally dry? You have a large cave filled with oil that has been pressurized and now empty. Does that pocket now collapse due to the pressure of the ocean's water?
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On Fri, 16 Jul 2010 05:17:37 -0700 (PDT), greg

The various crime syndicates in the US and Mexico will fill it with "evidence".
Joe
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On 7/16/2010 8:17 AM, greg wrote:

I would have to guess no.. I don't think they could release the oil quick enough to have it 'collapse'.. It's the water and earth above the oil pocket that keeps it pressurized, so as the oil is taken from the pocket, the pocket gets smaller..
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The short answer is "YES", but an oil deposit is not typically a cave. It is typically ocean bottom material that is permeated with crude oil. It is pressurized by the gravity of the bottom mass above it. As the oil is withdrawn over time, the oil pressure reduces, as this permeated material compresses. The length of time this takes depends not only the size of the field, but the compressibility of the geology. Very often older fields no longer producing what they once did are repressurized by injecting high pressure water into the field in order to increase field production. Steve

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Not a cave, it's porous(or not so porous) rock. Frequently, water displaces the oil, just depends. But subsidence CAN happen in oil fields, parts of Long Beach are a lot lower than they were before they started pumping early in the 1900s. 20 feet was the amount bandied about at the shipyard when I was there.
Stan
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On Fri, 16 Jul 2010 09:24:19 -0700 (PDT), snipped-for-privacy@prolynx.com wrote:

Same with New Orleans as I recall.
Gunner
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Frequently, water

Harris County, Texas, (Houston) has had major subsidence problems, particularly in the southern part, and down into Galveston County. Mainly because of ground water pumping.
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-0700 typed in rec.crafts.metalworking the following:

    So, it is not the sea level rising, as the ground is lowering. Well, we just wilt have to have the Obama stop that subsidence.
tschus pyotr
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On Fri, 16 Jul 2010 15:10:25 -0700, "Steve B"

Should have let it sink.

Found GeoJournal article ("only" $34 for a PDF) online: Land subsidence caused by ground water withdrawal in urban areas Thomas L. Holzer1 and A. Ivan Johnson2
Abstract: At least eight urban areas in the world have encountered significant economic impact from land subsidence caused by pumping of ground water from unconsolidated sediment. The areas, most of which are coastal, include Bangkok, Houston, Mexico City, Osaka, San Jose, Shanghai, Tokyo, and Venice. Flooding related to decreased ground elevation is the principal adverse effect of the subsidence. Lesser effects include regional tilting, well-casing failures, ldquorisingrdquo buildings, and ground failure or rupture. Subsidence of most of these urban areas began before the phenomenon was discovered and understood. Thus, the subsidence problems were unanticipated. Methods to arrest subsidence typically have included control of ground water pumping and development of surface water to offset the reductions of ground water pumping. Ground water recharge has also been practiced. Areas threatened by flooding have been protected by extensive networks of dikes and sea walls, locks, and pumping stations to remove storm runoff.
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On Sat, 17 Jul 2010 05:47:11 -0700, Larry Jaques

Vegas dropped something like 25' by the old well over SE of Valley View and 95.
SW
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wrote

Yeah, they sucked a lot of water out of there for a long time. That area used to be great, The Springs. We used to go rent horses at a place there and ride all over around there. Now it's landlocked by houses, but they did manage to preserve quite a bit of it, probably because it was too unstable to do anything else with.
Steve
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The difference between settlement from drawing down aquifer and an oil producing formation is the depth that the fluid is drawn from. Generally, water aquifers are much closer to the surface than the 5000' of the formation in question in the Gulf.
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wrote:

Many oil wells are under 1000 feet deep.
Gunner
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On Fri, 16 Jul 2010 09:24:19 -0700, stans4 wrote:

So, the sea level's not rising, the land mass is sinking? Is this another global warming "OOPS" moment? ;-)
Cheers! Rich
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short answer - yes - just look at long beach CA, for example, where as they drill the land subsides - solution - pump water back in as you take oil out. so, as the cavity of oil is emptied, they will probably put water in - if for no other reason so they can get the oil out by displacing it with water. but if they did nothing, the cavity would be unsupported and might well collapse

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I'm thinking water tends to take the place of oil. It may be injected into the well to get the oil out. I'm not an oil patch type.
I seem to remember the SPR (stategic petroleum reserve) needs water to draw down the reserves. I can't find a cite tonight so I may be wrong on that.
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
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(PDT) typed in rec.crafts.metalworking the following:

    Think of a sponge. That is to say, there isn't a large hollow space full of oil, but a lot of little holes in a porous substance. "Picture if you will..." a balloon holding a saturated sponge underneath a brick (the balloon simulates non-permeable strata, the brick all the strata on top; the ten thousand plus feet of "dirt" between the ocean bottom and the oil deposit.) Drill a hole through the brick, stick a soda straw in, and the oil "squirts" out. Eventually, the pressure between the brick on top and the sponge equalizes - the sponge gets "mushed flat". The well goes out of production. The field is "played out."     Yes, there will be some subsidence - happens where ever there is fluid (gas, oil or water) being removed from strata, and not being replaced. In some areas, water seeps in to replace the oil, percolating "up" as the oil is drawn off.

    No. It collapses due to the weight of the earth over the "played out oil field". Someone from the oil field can probably tell you how much oil is left after a field "plays" out - I've hear 80% gets left in some areas.
    But it is not like there is a bubble two miles down full of oil, so much as two miles down, there is a "sponge" full of oil. And pumping the oil out "compromises" the ability of the sponge to hold the top layers "up".
tschus pyotr
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pyotr filipivich
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On Fri, 16 Jul 2010 16:44:45 -0700, pyotr filipivich

Very well stated. Bravo!!
Gunner

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On Fri, 16 Jul 2010 05:17:37 -0700 (PDT), greg

The response is rather complicated but essentially there is no large cavern down there that was filled with oil and is now dry. What does exist is a porous, usually some sort of rock, area which is now depleted of the liquid that it once contained.. Several techniques have been used. Forget it, leave it alone... sometimes results in sinkage of the surface regions just as taking water from an aquifer may. Injection ... water is often injected into the reservoir which does two things. It re-loads the structure with liquid and, two, it may increase pressure (that is rapidly depleting) in the structure being produced from. In most cases, a depleted well is simply permanently plugged with concrete and abandoned.
Cheers,
John D. Slocomb (jdslocombatgmail)
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On Sun, 18 Jul 2010 06:53:54 +0700, J. D. Slocomb

Oddly enough..they have been finding that fields once considered depleted..are somehow replenishing themselves.
Google has some interesting cites on this rather odd factoid.
Gunner

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