Why doesn't the eath's crust collaspe when oil is removed leaving huge empty caverns underneath?

Question

If you dig a well and the well eventually becomes dry, the hole created is more likely to collapse when something rolls over it becoming a sinkhole.

Imagining taking billions of barrels of oil out of the ground it seems logical that one day Saudi Arabia could become lower by the ground collapsing under the weight of cities being built near where the oil was removed creating huge sinkholes.

Answer 1

because we pump water in place of it.

Answer 2

Liver P is right. oil drillers dig for oil, and when the well dries up, they fill it with water, which keeps the earth muddy. sinkhole problem solved.

Answer 3

because mud is pumped in (so I've heard)

Answer 4

I have read they have developed ways to put Carbon Dioxide gas back in the empty wells, since oil fields are also natural gas fields as well.  Mostly hear about water being pumped back in just like those above me already stated.

Answer 5

The real reason they do not simply collapse is because petroleum is collected from the pore spaces in the bed holding the fluid.  The bed most have high porosity and permeability to be pumped but the area is by no means hollow.  (The same is true for most water wells too, karst  type sinkholes excluded))

There can be settling, slowly over time.  Pumping water back into the beds can slow or stop the settling.  But the real reason the companies pump the water back in is to increase oil production and get rid of dirty water.  AS soon as it no longer maintains production high enough to be profitable they stop pumping.  Underground caving is self limiting, enough rock falls to fill the hole enough to support the roof, the breakage does not run to surface unless the original hole is very close to surface to start with.  Oil wells are deep and while some settling in some areas has been noticed it is rare and of small effect.