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room16

A Question I keep asking myself...

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Given todays urgent needs for oil and the ever depleting stocks, i set about wondering exactly what unexpected consequences would come from what these companies are doing?

My question is what will be the after effects of removing what was once sandwiched inbetween 2 solid surfaces, a compressed and fermented treacle. Is this not supporting the layers of earth above? Will removing all the oil reduce support for the layers above and thus result in more earthquake and movement in the crust?

Sorry if its a noobie conclusion/question. But to me, if you remove something that is under enough pressure to spuirt from the ground, then surely its under pressure as its supporting something? thus no support and eventual collapses in area's where its weaker?

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Chris

As far as i understand it the oil companies pump water into the said cavities to put as much volume in as they take out.......I could be wrong and it wouldn't be the first time.....

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Sounds plausable, still unsure on what the effects might be if there is not enough pumped back in. Also what sort of effect this would have with regards to corrosion? Would water no contain elements that would cause more damage?

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Given todays urgent needs for oil and the ever depleting stocks, i set about wondering exactly what unexpected consequences would come from what these companies are doing?

My question is what will be the after effects of removing what was once sandwiched inbetween 2 solid surfaces, a compressed and fermented treacle.

Oil and gas is dispersed throughout the structure of underground rock, in small spaces like in a sponge.

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This is not such a daft question and in the right circumstances some of the effects you mention can occur, not withstanding that oil deposits are distibuted in small pores rather than large 'open' depositis, as Jim said.

Indeed this very effect has been experienced in the North Sea. The Ekofisk field where the reservoir rocks were largely chalk - the water injected to displace the oil began to dissolve some of the chalk in certain areas of the formation which was redepositied in a less porous manner - the result was a projected several metres of subsidence.

The entire production complex, at the time some 7 platforms in total - five of which were interconnected above sea level (I thinkl), had to be raised by 6m to counteract the settlement.

It was one of the most complex and interesting structural engineering projects of the time (late 1980s) with 4 or 5 interlinked platforms literally being jacked up simultaneously to allow the 6m support inserts to be placed.

That having been said the effect is a peculiarity of the chalk formation and is not characteristic of the more common sandstone reservoirs.

Edited by Iris

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This is not such a daft question and in the right circumstances some of the effects you mention can occur, not withstanding that oil deposits are distibuted in small pores rather than large 'open' depositis, as Jim said.

Indeed this very effect has been experienced in the North Sea. The Ekofisk field where the reservoir rocks were largely chalk - the water injected to displace the oil began to dissolve some of the chalk in certain areas of the formation which was redepositied in a less porous manner - the result was a projected several metres of subsidence.

The entire production complex, at the time some 7 platforms in total - five of which were interconnected above sea level (I thinkl), had to be raised by 6m to counteract the settlement.

It was one of the most complex and interesting structural engineering projects of the time (late 1980s) with 4 or 5 interlinked platforms literally being jacked up simultaneously to allow the 6m support inserts to be placed.

That having been said the effect is a peculiarity of the chalk formation and is not characteristic of the more common sandstone reservoirs.

<<This is not such a daft question and in the right circumstances some of the effects you mention can occur, not withstanding that oil deposits are distibuted in small pores rather than large 'open' depositis, as Jim said.>>

Eh? I said no such thing sir!

I told the original poster that oil was distributed throught the rock in small spaces as in a sponge - or words to very similar effect.

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<<This is not such a daft question and in the right circumstances some of the effects you mention can occur, not withstanding that oil deposits are distibuted in small pores rather than large 'open' depositis, as Jim said.>>

Eh? I said no such thing sir!

I told the original poster that oil was distributed throught the rock in small spaces as in a sponge - or words to very similar effect.

You misunderstand sir! ;)

While I was not quoting you I was paraphrasing but I can see how you have interpreted my statement.

To avoid doubt I was making the same point as you - that oil is generally depositied in small pores/voids etc - as you said - of course I did embellish it with the reference to large voids (er open deposits)...

Edited by Iris

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"You misunderstand sir!

While I was not quoting you I was paraphrasing but I can see how you have interpreted my statement.

To avoid doubt I was making the same point as you - that oil is generally depositied in small pores/voids etc - as you said - of course I did embellish it with the reference to large voids (er open deposits)..."

LOL

I think your original remark is ambiguous at best. ;-)

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A little ambiguity is a good thing - it gives life extra meaning ;)

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As mentioned earlier the 'way' oil is held in reserves is more like a sponge type of 'picture'... there are sometimes more 'voidlike' reserves ..

Brine is often pumped in to aid in the recovery of the oil. Modern techniques are making previously 'depleted' reserves more viable again..

I have worked in Saudi Arabia and other middle-eastern countries (geology/oilfield work) and while there are measures to reduce problems associated with rock movement... on the whole I think if it is going to move..it will move...

Small tremors are quite common in Middle Eastern Oilfields due to the 'rebound/shift' of deeper rock layers , the first one i experiences gave me quite a fright one morning.

Steve

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thanks for bringing this back to the original question Steve, interesting response ;)

let's keep this to the question folks and less of a discussion about semantics... cheers

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I always thought the same a Jamie..

They pump sea water into the well which then forces the oil up. So eventually when the cavern is emptied of oil it is replaced by the water so in theory the earth above is still supported.

But then I also could be wrong.

Time to ask YetiMonster as he works on an oil rig.

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nice one Chris ;)

yes, where is YetiMonster? He needs to get in here and put our minds at rest... I've never thought about this much, but now it's been discussed on here, it's really thought provoking ;)

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