once the pressure has been equalized in the immediate vicinity

[keannu]

Sorry, this may need some scientific knowledge. Why do you think "equalized pressure in the vicinity of a well" causes more energy to pump the oil? I can't get how pressure equlization happens in the vicinity. This is a workbook for the college entrance exam.

st165)If a sizable oil reserve is discovered, wells are drilled to tap into the oil reserve. Oil in the ground flows at about the same rate as damp in a stone foundation, the one major difference being that the oil is held at much higher pressure. When a new well is drilled, the open hole gives free passage to the pressurized oil immediately around it, which then surges to the surface. However, once the pressure has been equalized in the immediate vicinity of the drill hole, it takes more and more energy to pump the oil through the rock or sediment to the well. Eventually you will reach a point where you must invest as much energy to pump the oil as you will get out of it. When this point is reached, production ends and the well is capped forever.

 

[SoothingDave]

"As damp in a stone foundation" seems odd to me. I'm used to "damp" as an adjective, not a noun.

That said, you need to consider the oil underground like it's inside of a balloon and someone is squeezing the balloon. When you first drill the hole, the oil shoots out because the pressure of the oil underground is higher than the pressure of the air outside.

So the oil flows with no effort or work put into it.

However, like a balloon you puncture, the pressure is released because the material (substance) inside is being released. Eventually enough oil has come out that the pressure underground has lowered to the point where it is equal to the pressure of the air above ground. There is now no force that naturally brings the oil up through the drill hole.

Now, you have to use energy to pump the oil out of the hole.

 

[bhaisahab]

"Damp" is common as a noun in BrE.

 

[BobK]

Sorry, this may need some scientific knowledge. Why do you think "equalized pressure in the vicinity of a well" causes more energy to pump the oil? I can't get how pressure equAlization happens in the vicinity. This is a workbook for the college entrance exam.
...

It can't not happen. Nature abhors a vacuum. When anything is at a higher pressure than something else, it 'squirts' there. Oil extraction is cheaper when it can take advantage of this 'natural squirting'. After a while the higher pressure drops to the surrounding pressure, and extraction becomes uneconomic.

(I'm not a mineralogist, but this is just schoolboy physics.)

b

 

[Route21]

I believe the key statement in your extract is:

"Oil in the ground flows at about the same rate as damp in a stone foundation"

The oil in the ground is under pressure.
You drill a well and this allows the pressure at the bottom of the well to force oil up to the surface.

Unless you have done things like the "acidising" of gas wells that we used to do,, to open up many routes for fresh oil to get to the well, then the pressure at the base of the well will decrease, as oil further from the well has to overcome the "stone foundation's" resistence to its flow.

To increase the pressure of the oil and hence improve oil recovery, you may have to resort to things like water injection to pressurise the oil reserve and force it to and up the well.

This is a simplified version of what happens written as someone on the peripherals of offshore gas drilling, but I hope it gives a bit better understanding of what goes on.

Regards
R21

 

[Route21]

There's an interesting article on Wiki that shows fracking to help release hydrocarbons from shale oil deposits, which may also help, as shale oil deposits are very similar to your case.

Hydraulic fracturing - Wikipedia, the free encyclopedia

Hope it helps
R21

 

[keannu]

I almost forgot about this passage, when "immediately" came into my mind, so I need your last help. It seems it can be interpreted as either "time-wise right away" or "space-wise in the vicinity". Of course, the latter has more potential, but what do you think?

ex)If a sizable oil reserve is discovered, wells are drilled to tap into the oil reserve. Oil in the ground flows at about the same rate as damp in a stone foundation, the one major difference being that the oil is held at much higher pressure. When a new well is drilled, the open hole gives free passage to the pressurized oil immediately around it, which then surges to the surface. However, once the pressure has been equalized in the immediate vicinity of the drill hole, it takes more and more energy to pump the oil through the rock or sediment to the well. Eventually you will reach a point where you must invest as much energy to pump the oil as you will get out of it. When this point is reached, production ends and the well is capped forever.

 

[Route21]

Yes. "..immediately around it ..." means ".. space-wise in the immediate vicinity/area around it...".

Regards
R21

 

[konungursvia]

Oil spurts out at first because of high pressure. All around the drill hole, the oil flows up and out. Soon there is so little oil in the permeable rock around the drill hole that a pump is needed to continue to extract oil. Oil is not sitting there in underground tanks, in a continuous liquid, it is flowing through sand, rock, and other mixed matter, including solids, liquids and gases.

 

[BobK]

Yes. "..immediately around it ..." means ".. space-wise in the immediate vicinity/area around it...".

Regards
R21

Passing thought: that's what the (etymological) metaphor means - in medio [='in the middle']. Temporal 'immediately's probably outnumber spatial ones now, but here it refers to space.

b