if we pump out oil from under the earth surface what fills the space when the oil is removed?

Answer 1

The oil is usually filling the spaces in rock. It's not quite like mining a coal seam.

Imagine that you have a jar full of pebbles. Now imagine adding dry sand to the jar. The sand fills the spaces between the pebbles. Now see how much liquid you can add to the full jar. This is something like how the oil is held in the oil-bearing strata (though under great pressure).

At first the pressure is enough that the oil (and any gases and water that are mixed in with it) comes to the surface but once that is exhausted, steam, CO2 or water can be used to extract more.

Nothing will immediately collapse because the oil is removed, though, of course, removing the oild DOES change the pressure in the strata and this surely must eventually have some effect.

Answer 2

When first drilled, an oil well is under high pressure, and the oil flows out of it with no help. Over time, the pressure on the well equalizes. Oil platforms maintain production by compressing natural gas (which comes out of oil wells naturally), and pumping it back into the well. Once the well is no longer considered viable, the pressure is bled off of it and the well is capped (sometimes it will also be destroyed with explosives). When this occurs, the "formation" of the well will often collapse, like an underground cave-in. What remains is a mixture of soil, rock, and groundwater or seawater with natural gas difused throughout it.

Basically, the space that the oil takes up is only there because the formation of oil and gas has put pressure on the surrounding earth. Removing the oil releases that pressure, and the dirt shifts to fill the space.

Also, it's important to remember that oil isn't sitting around in big underground pools. It's already mixed into the soil, absorbed into it like a sponge. The only thing that keeps an oil formation together is the pressure that's on it. The "holes" in the sponge are kept open by pressure.

Answer 3

Actually this is a real problem in oil extraction - initially because there are all sorts of gases (methane, etc.) building up underground, when the well is first drilled the oil is often under high pressure, sometimes literally bursting out of the ground in a stereotypical fountain. As time goes on, however, this pressure is released, until eventually the oil has to be physically extracted out of the ground. Since suction is impossible (it'd be like trying to suck all the air out of the inside of a glass bottle - impossible, or it would take tons of energy), instead liquids are frequently pumped back into the ground in order to force the oil out. Usually this is water, sometimes wastewater or sometimes diverted from a river. It may also be other gases - as the above reader said, CO2 is one possibility. Whatever is pumped in there is usually trapped in there for good. This is problematic if you're pumping in river water, since it results in natural aquifers being permanently depleted of their water supply.

Answer 4

There is a plan to pump in co2 to fill in the empty space and make pumping oil out easier.

Answer 5

Sometimes nothing. Where I used to live in Southeast Texas some people started getting sinkholes in their yards. The holes would get larger and larger and sometimes swallow up their houses. They finally figured out that it was from oil being pumped out of the ground. It left empty caverns underground and the ground gave way and there went their houses!

Answer 6

Nothing, it leaves a void. Also, some deposits are under great pressure, so that when we pump oil out, the remainder just expands.

Answer 7

.Water mostly, oil floats on water, so if the oil is in a cavern
then water seeping in will cause the water to float on top.
In fact in real old wells they sometimes pump in steam to cause the oil to thin out and flow easier....

In someplaces it is becoming common to pump the empty wells full of toxic wastes....

Answer 8

nothing I guess, but there are many pockets of empty space under the earths surface so I guess its not really that big of a deal.

Answer 9

Air