General Question

pleiades's avatar

What happens to the space of the earth where oil was taken from?

Asked by pleiades (6571points) June 25th, 2014

On geological level, does removing oil from the earth create shifts in tectonic plates or the ground in general?

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7 Answers

thorninmud's avatar

From here:

“Oil fields are not big caves in the ground despite how diagrams show them. Oil and gas are tucked into the spaces between the rock particles known as the porosity. An oil field is more like a block of porous Styrofoam full of oil than it is a big bag of oil.

In most cases, the rock grains are touching and the rock supports itself even without the oil in it (like dry sandstone you find in buildings and walls). So when oil is removed there is no change. In most cases, water flows from the surrounding rock into the spaces left behind by the oil.

You go from an oily block of rock (Styrofoam) to a watery one. ”

majorrich's avatar

Often, brine is injected to both aid in extracting the oil and to fill voids.

antimatter's avatar

Very interesting can’t say much to contribute to this question. I always wondered what happened under ground. I thought for that it would be like open caves when the oil were extracted.

CWOTUS's avatar

Most often, with older oil fields that relied on simply pumping oil out of the ground as long as possible – nothing at all. Sometimes the ground subsides, whether that’s even measurable or not (it probably would be with good enough instrumentation, but there’s been no call to do so, I think).

Or in more recently developed fields, or fields that are being “recovered” after having been abandoned sometimes decades ago, what @thorninmud and @majorrich said.

Sometimes the assumption that “nothing happens” can be correct, if the oil (or gas) is pumped from a stable enough strata, but I don’t think that is common.

This doesn’t account for the times that we fill voids with the rusting hulks of used pickup trucks, of course.

A related question that you may not have considered is “What happens when water is pumped out of huge aquifers?” The same thing happens as described by @thorninmud – the rock just gets drier, but there is so much water that in many cases the ground does subside, and it is of interest and measured. I don’t have any current links, but I’m sure that if you look for “Oglalla Aquifer subsidence” you’d find plenty on your own.

ARE_you_kidding_me's avatar

It just lowers the pore pressure.

Dan_Lyons's avatar

Oil in the Earth acts as a lubricant which allows tectonic plates to slide smoothly over one another.
Remove the oil and watch as more and more earthquakes become more and more common.

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