Oily question?

Question

When all of those millions of gallons of oil are extracted from the earth every week, what takes its place? I mean what fills the space where the oil was before it was taken out?

Answer 1

The short answer...... Generally is it salt water.

Crude oil floats on water and natural gas floats on oil. The most common reservoir rock is sandstone. Gas, oil, and water reside in the pore spaces in between between the sand grains. Oil and natural gas push to the top of the sandstone and must be confined by some sort of trap. Either a dome like structure or a fault where the formation above the reservoir rock is impermeable like shale. Otherwise the hydrocarbons would migrate off. The whole system is under pressure, mainly due to its depth and the salt water pushing up from below.

Drilling in to the top of the reservoir, if you are lucky enough to do that, introduces an area of lower pressure, the well bore. Natural gas and oil move from the higher pressures of the reservoir to the lower pressure well bore. As production takes place, salt water from below pushes the oil and gas up and out, replacing it in the pore spaces. Eventually the well will "water out" meaning it is producing more salt water than oil or gas and becomes uneconomical to operate any more.

Now there are secondary recovery techniques that introduce water, mud, steam, polymers, etc. into wells down structure from the producing well to try to "flush out": more oil. But, generally the pore spaces fill with salt water after the oil and gas are pumped out.

This is general mechanism of how this works. The science and engineering are far more complex, but I hope this answers your question.

BTW - under certain circumstances, even though the oil and gas has been replaced with salt water, the lower pressure in the reservior rock is not enough to maintain its structural integrety and it collapses. This can cause subsidence at the surface, often over vast areas.

Answer 2

Oil/petroleum is made of hydrocarbons. These are formed from some special type of geological rocks.
There are five elements which all have to be present for a prospect to contain hydrocarbons. If any of them fail, then we get a dry hole.

A source rock - When organic-rich rock such as oil shale or coal is subjected to high pressure and temperature over an extended period of time, hydrocarbons form.
Migration - The Hydrocarbons are expelled from source rock by three density-related mechanisms: the newly-matured hydrocarbons are less dense than their precursors, which causes overpressure; the hydrocarbons are less dense than the ubiquitous water medium, and so migrate upwards due to buoyancy, and the fluids expand as further burial causes increased heating. Most hydrocarbons migrate to the surface as oil seeps, but some will get trapped.
Trap - The hydrocarbons are buoyant and have to be trapped within a structural (e.g Anticline, fault block) or stratigraphic trap
Seal Rock - The hydrocarbon trap has to be covered by an impermeable rock known as a seal or cap-rock in order to prevent hydrocarbons escaping
Reservoir - The hydrocarbons are contained in a reservoir rock. This is a porous sandstone or limestone. The oil collects in the pores within the rock. The reservoir must also be permeable so that the hydrocarbons will flow to surface during production.

Answer 3

the oil is not in a big empty space. it is in the rock (imagine a sponge). to get the oil out they drill down, the oil then migrates out as there is less pressure in the area where there is a drill hole. After this they may drill a second hole and pump natural gas down to force out the oil. (this is a REALLY basic explanation, what they do is much more complex). To do all this the host rock must be both permeable and porous.

look here for a batter basic overview:

http://www.bydesign.com/fossilfuels/links/html/oil/oil_get.html

Answer 4

Depends on the technique being used. With some techniques, nothing replaces the crude removed. With other techniques water replaces the crude. However, the water does not stabilize the ground. Rather, the holes are relatively small and do not generally destabilize the surrounding surface area. (Of course there can be environmental destabilization, but I don't think that's what you're getting at with your question.)

Answer 5

Probably the earth just sinks in to fill the area where the lake of oil was.

Answer 6

Jelly and ice cream. Unless it is under the north sea in which case it is Marmite every day of the week except thursday which is of course Peppermint cordial day.

I Hope this helps.

Regards

Answer 7

Nothing. It takes thousands, if not millions, of years for oil to form.

Dead creatures are fossilised, turn into limestone then into oil.

Answer 8

water apparently.
I always wondered if the oil lubricated the tectonic plates and thats why we get more earthquakes nowaday since there's harldy any left

Answer 9

they pump water in to push the oil out . oil floats on water.

Answer 10

Think BP chuck all their loose change down the hole out of the billions & billions they are making out of everybody