Oil seems to pop up everywhere, in shale,
under deserts and plains, and of course, underwater.
But if oil is a "fossil" fuel, how did those
fossils get under the ocean?
Hey slick, Trace here for DNews.
Oil is a mystery.
Scientists don't really 100 percent know where
it came from or how it got underground, but
because we know about plate tectonics we at
least have some ideas of how it got under
the ocean.
Oil is what we call a fossil fuel.
It comes from dead things, especially when
there are a lot of them gathered in one place.
It's true that oil famously comes from deserts
like on the Arabian peninsula, but that location
is, well, more-or-less random.
Roger N. Anderson of Columbia University told
Scientific American, "Plate tectonics determines
the location of oil… reservoirs."
Because the Earth's surface is constantly
changing and shifting, oil can end up in all
sorts of weird places…
It helps to understand how oil is made first
though.
Hundreds of millions of years ago, organic
material (prehistoric plants and animals)
accumulated at the bottom of oceans, rivers,
swamps.
Think of it this way, the ocean is deep, and
when things die at the top, they can sink
all the way to the bottom.
When that happens a lot, they'll pile up!
Living things are made of proteins, carbohydrates,
lipids (or fats) and lignin (woody polymers).
When these decomposing organics become compressed
under more and more material, in an anoxic
environment, they break down strangely.
Essentially, the organic matter had to die
and quickly find it's way to a place without
oxygen to avoid decomposition.
Oceans are great for this because the seafloor
is not very oxygenated.
At that point it breaks down SUPER slowly,
so more and more dead stuff can build up and
adds more and more pressure.
Eventually, the pressure of all that material
forces the water out; the proteins, lignin
and carbs break down; and all that is left
is a lipid, sugar, and amino acid ooze.
Occasionally, this happens near enough to
a crack in the crust that it can become trapped.
Then, by adding heat and pressure (something
geology and plate tectonics is great at),
this mix of decomposed organisms become subject
to chemical reactions, forming what's called
kerogens.
Over millions of years and with more heat
and pressure it goes through catagenesis where
the kerogen cooks into hydrocarbon chains.
Humans then look for telltale signs of the
these deposits.
When that happens though, it doesn't form
a giant lake or pool under the ground; it's
actually stuck in the pores of surrounding
rocks, like water clinging to a windowpane.
The immense pressure of the Earth's crust
can keep the oil trapped under solid rock,
but if an oil well pushes through it at the
right place -- the oil can gush out in a tower
of black liquid.
Companies can then take this and make petroleum!
(WHEW)!
The more we understand about where ancient
seas and forests were, the better scientists
can predict where oil is trapped in Earth's
crust today.
So, because oceans are great at providing
the perfect conditions of low oxygen and high
pressure, AND it’s where a lot of this decomposing
organic animal and plant matter accumulates…
oil could be anywhere there used to be an
ocean.
As the Earth's crust is constantly shifting,
the locations of these ancient oceans have
moved too -- scattering oil across the planet;
70-percent of which is covered by water -- so
there's likely a lot of oil trapped under
there!
Getting at that oil isn't easy though.
Deepwater Horizon -- could reach 10,000 feet
to the ocean's floor, and then drill over
30,000 more feet into the rock to extract
the oil.
The tallest building in the world, the Burj
Khalifa, is only 2717 feet.
In the end, we think oil got down there because
the Earth is constantly changing.
What was once under the ocean is now on top
of Mt Everest -- they have undersea fossils
that they found there.
And what was once on top of the world, is
now at the bottom of the sea.
How poetic.
We'd like to thank our sponsor for this episode
for helping support DNews today: Deepwater
Horizon, the movie.
Check out Deepwater Horizon, based on a true
story.
In theaters September 30th.
After learning all about oil, maybe you're
curious about how we take uranium and we turn
that into nuclear fuel as well?
Luckily, we have a great video on that
right here.
Are there other processes you want to know
about?
Should we look into how oil is refined?
What do you want to know about the world around
you?
