Are we harming the structure of the earth by taking so much oil out of it?

Some people think the oil inside the earth is part of a support structure that helps keep the world round. But according to Rebecca Walsh Dell — a PhD candidate in physical oceanography who is jointly affiliated with the Program in Oceans, Atmospheres, and Climate in MIT’s Department of Earth, Atmospheric, and Planetary Science, and with the Department of Physical Oceanography at the Woods Hole Oceanographic Institution — that’s not the case.

“The earth is like a can of soup,” she says. “Its strength comes from the can, not from the soup, and an empty can is still stackable. Granted, it’s possible to have some ground subsidence after drilling for oil, but this tends to be small and slow. So even if we were able to drain the very last drop of oil from the planet — which we’re not — it wouldn’t do any direct harm.”

The reason the earth won’t collapse into itself is because the oil isn’t in the ground per se; it’s in rock. How it got there and how humans get it out of there has a lot to do with the question of how much there is and what might be the consequences of future drilling.

“The Earth wasn’t born with oil in it,” says Dell. “Millions upon millions of years ago, microbes in the oceans lived and died, then sunk to the bottom and were covered by layers of sediments. Over a long period of time heat and pressure built up, which meant that this organic material did not decompose in the normal way. Instead, it was transformed into hydrocarbons, what we call crude oil.”

This oil is not just sloshing around inside the earth in gigantic gooey reservoirs. It’s actually stored in rock, which is why it requires enormous machinery to reach it and draw it out. “If you saw the movie There Will Be Blood, you saw geysers of oil coming out of the ground,” says Dell. That’s ‘easy’ oil, meaning it’s near the surface and inexpensive to get out. In the U.S., that oil is all gone.”

The real question, then, is how much crude oil can drilling companies get out of the ground profitably? If the cost and energy required to draw out a barrel of oil is more than what the market will pay for that barrel of oil, no one is going to pull it out of the ground. For example, it is believed that there may be extensive oil reservoirs in the Arctic, but it would be very expensive to drill there. So until it can be done cost-effectively, it’s not likely to be tapped.

Over the last couple of decades, new methods of extraction that break up the rock in which oil (or, more often, natural gas) is stored have gotten more popular. Hydrofracturing — or “fraking” — is process wherein water is mixed with sand and chemicals and forced into a well at high pressure, fracturing the rock and making it easier for the gas to flow out. Though effective, this method is not without its environmental impacts. “Fraking can cause earthquakes,” says Dell, “and while they are too small for a person to feel, scientists and engineers are trying to find out if it can contribute to stronger ones.” Fraking is more likely to harm the earth through spills of oil or other chemicals on the surface, Dell adds, and by environmental disruptions from the drilling itself — not to mention by how that gas and oil will contribute to climate change by being burned.

While we’ll never get all the oil out of the earth, we will reach what is known as “peak oil” — the point where oil production stops growing and begins an eventual and permanent decline. Experts agree that North America has long since reached peak oil, though there are countries where there is still capacity to expand production.

“As an oceanographer,” she says, “my concern is not that we’ll run out of oil, but that we’ll use all the oil we have, which will have serious consequences for the climate. I would rather see us move away from oil before it’s all burned. We’re taking some steps in that direction, but also some steps in the other direction. So in terms of harming the earth, it’s much more a factor of burning oil than drilling Curled from http://engineering.mit.edu/engage/ask-an-engineer/are-we-harming-the-structure-of-the-earth-by-taking-so-much-oil-out-of-it/