What happens to the cavities in the earth after the oil is pumped out?

Question

What happens to the cavities in the earth after the oil is pumped out?

Answer 1

all the answers are right.  sometimes fluid is injected into the ground to drive out the oil, sometimes the ground settles a bit when the oil is removed, and sometimes groundwater in the surrounding rock and sediment migrates in when the oil is taken out.

Answer 2

They are filled with salt water which is pumped up with the oil.  Many wells have  salt water pumped in to help force the oil to flow better.  Oil underground is not just a big open cavity.  It is in small cracks and fissures between rock which must be opened up to flow.

Answer 3

They are filled with water, but not necessarily salt water.  It can be fresh groundwater, which is often found below the oil. and rises through the rock as the oil is removed.

Answer 4

Some simply collapse.  Called subsidence.  A big one just West of Bakersfield, CA.

Answer 5

In Long Beach where is a water injection program. Pure water.