I would like to know if there is any science available that has
determined what the impact on the earths surface will be when we have
totally depleted the subterranean oils?

I'm not a geologist, so I can't give you an expert assessment. But I
can say that oil isn't, as many people visualise it, trapped in
cavernous pockets, which would be left spatiously empty once the oil
is drained from them. On the contrary, crude oil is trapped amid
porous rock. It's closer to being held in a sponge than a cave. So
when the crude oil is finally exhausted from an underground reservoir,
there's really plenty of stuff still in that region to support the
weight of the strata above.

   Do you see movies of an oil well at the moment it taps the reserve?
It gushes because it's under tremendous pressure from the weight of
the overlying layers of rock. As oil is drained that pressure drops.
In time it takes agressive work to force more oil out of the ground.
Eventually it costs more to pump what's left than will be made by
selling it at market prices, and so the field is abandoned.

   But one way or another, the pressure is off the liquid oil, yet the
ground remains effectively intact. There's plenty of space-occupying
stuff left in the field to support the overlying strata, which itself
is usually thousands of feet deep. Consider this: There are many
places with networks of caves not more than a few hundred feet beneath
the surface. These caves really are vast empty caverns, yet the ground
above doesn't settle.

It is unlikely that we will ever "totally deplete" the subsurface of
petroleum.  As qed100 has pointed out, extracting petroleum (or any
fluid) from the subsurface is like trying to suck water out of a
sponge with a straw (the straw being analogous to an extraction well).
 There will always be some residual liquid in the matrix (rock or
sponge) due to capillary forces.  Even the most advanced of the
current petroleum extraction technologies only recover about 20-40% of
the oil that's present.  Future advances might push this number to as
much as 60% in favorable cases.

That having been said, extraction of petroleum (and also groundwater)
resources from the subsurface results in the subsidence of the land
surface as the subsurface compacts in response to the extraction of
fluid.  This subsidence can be quite rapid; measurements of of
subsidence rates as much as half a meter per year have been made using
satellite-based radar interferometry.

The general question of subsidence in response to petroleum extraction
has already been addressed on Google Answers (see
http://answers.google.com/answers/threadview?id=335789).  Note,
however, that livioflores' comment on that question is absolutely
incorrect.

A Google search on 'subsidence petroleum' (without the quotes) will
get you lots of additional information.

You might enjoy reading this book:

The Last Hours of Ancient Sunlight by Thom Hartmann
http://www.thomhartmann.com/last.shtml

I am a Mechanical Engineer. More appropriate is to say that I am in
Petroleum field for over 26 years. Oil depletion appears to be a
strategy to increase crude oil prices. If you see BP's Oil Reserve
statistics, published every year and available on the net, you will
note that world oil reserves are on the increase. Bruce Hamilton in
his treatise on Gasoline has indicated that Oil is available for the
next 4,000 years. The Abiotic Theory of oil is gaining the upper hand
now. When Oil is taken out, water or other materials are pumped inside
so that Oil comes out. In fact, oil is ejected out by the pumping of
water, mud or Gas into the well.

"Bruce Hamilton in his treatise on Gasoline has indicated that Oil is
available for the next 4,000 years. The Abiotic Theory of oil is
gaining the upper hand
now."

   Interesting. But a treatise does not a fact make. Does Hamilton's
argument propose an observational test, other than waiting another
4,000 years to see when oil actually expires?

Hi,

I am a graduate student in meteorology but I did my undergrad in
Environmental Science.  There have been cases of the earth physically
sinking due to the removal of underground water but none to my
knowledge due to oil.  When you think about it, oil is a product of
time, ergo it will not usually be as close to the surface as water. 
The biggest impact to the surface of the earth will be a result of the
actual process of removing the oil, particularly as we deplete those
oil stores which are closer to the surface.

Of greater concern than the impact to the earth's surface, is the
impact to the atmosphere.  Plants remove carbon from the air, store it
in the soil, and over time it is burried.  The cycle that would
naturally liberate this carbon is very slow.  Carbon dioxide is a
greenhouse gas and we are basically taking large concentrated stores
of it and releasing it into the atmosphere, thus reducing the amount
of immobilized carbon and increasing its concentration in the
atmosphere.

"Of greater concern than the impact to the earth's surface, is the
impact to the atmosphere.  Plants remove carbon from the air, store it
in the soil, and over time it is burried.  The cycle that would
naturally liberate this carbon is very slow.  Carbon dioxide is a
greenhouse gas and we are basically taking large concentrated stores
of it and releasing it into the atmosphere, thus reducing the amount
of immobilized carbon and increasing its concentration in the
atmosphere."

   Yes. And this is very analogous to the potential hazard to the
ecosystem by heat pollution. Let's say hypothetically that a so-called
"clean" energy source is found, meaning that it releases no chemical
wastes into the environment. It remains that use of an energy source
entails conversion to work. Since no conversion process is 100%
efficient, some of the energy invoked will find its way into the
environment at large in the form of gross heat. If said source were
also cheap and very abundant, a civilisation employing it liberally
would be constantly pumping heat into Earth's thermosystem which in
pre-technological times was nearly dormant.

   This is, of course, exemplified by any source of energy not found
active on Earth. Oil and coal store chemical potential energy which at
earlier times took, as you've said, millions of years to cycle through
the system. The role of these was so slow that they presented no shock
to the biological system. Fissioning Uranium is the same way, though I
wouldn't say that its current use is at a critical level.

   Supposing however that nuclear fusion is perfected and is able to
provide enormous wattages of energy. It would of course release energy
which had for billions of year been stashed away in the nuclei of
atoms. With a population as large as the one now standing, we could
really hurt ourselves.

I am geology student currently researching and writing a report on
subsidence due to subsurface fluid removal. Fluids underground are
trapped in porous (spongelike) rocks and are usually under high
pressure. Their removal can result in subsidence on the surface which
forms a subsidence dome, however subsidence of over 2m is rare. An
example of subsidence due to oil extraction is the Wilmington oilfield
in California. This happens because the decrease in pore fluid
pressure allows the rock strata above to compact the porous rock and
subsidence results. Its impact though relitively small has been
estimated to cost the US $100 million a year due to building damage
and damage to the oil pumping infrastructure itself. One technique
which aids fluid removal is the repressurisation of the porous rock
with seawater or steam which can counteract the effect of a loss of
pore fluid pressure due to hydrocarbon removal. You might also want to
look into induced seismic activity which has been associated with this
repressurisation, although it has also been linked to the construction
of dams and other constructions.

What is wrecking havoc on the earth's surface is the depletion of the
earth's natural aquifiers. many predict that even before oil runs dry,
water supply Mexico City has sunken over 30 feet in the past 100
years. Venice, Yemen, and many other places worldwide are facing
similar situations due to aquifier depletion.

http://worldnetdaily.com/news/article.asp?ARTICLE_ID=47169