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  • 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 oilreservoirs."

  • 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?

Oil seems to pop up everywhere, in shale, under deserts and plains, and of course, underwater.

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B1 US oil ocean trapped crust pressure earth crust

How Did So Much Oil Get Trapped Under The Ocean?

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    joey joey posted on 2021/04/16
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