Fracking explained

Australian Community Media

You’ve heard of fracking, and you’re pretty sure lots of people don’t like it, but do you know how it actually works? Footage courtesy: HowStuffWorks.com

Transcript

00:00 Fracking, you've heard of it, you know it's controversial,

00:02 but you might not know what it actually involves.

00:05 Never fear, we're here to put some fracking knowledge

00:08 in your brain.

00:09 Fracking is the delightfully cheeky sounding nickname

00:12 for hydraulic fracturing,

00:14 which sounds a little bit less delightful

00:16 and more like something you do to your enemies in StarCraft.

00:19 But no, it is something we do to rocks.

00:21 In the simplest terms, hydraulic fracturing

00:24 is a way of getting more of the valuable fluids

00:26 like oil and natural gas out of geologic formations

00:29 under the ground.

00:30 But these fossil fuels aren't like big lakes

00:33 where you can just stick a straw in and suck.

00:35 These reserves of oil and natural gas

00:37 are found locked up in pores

00:39 distributed throughout vast layers of rock like shale.

00:42 So how do you get them out at a reasonable pace?

00:45 Let's look at a typical fracking setup

00:47 for something like shale gas.

00:49 You start with a deep vertical well,

00:51 drilling a hole down to the level of the shale

00:53 that you want to mine.

00:54 The depth will vary, but just for example,

00:56 one company claims its average fracking well depth

00:58 is 7,700 feet.

01:01 That's deep.

01:02 Almost one and a half miles are about 2.3 kilometers.

01:05 When you're at the right depth,

01:07 you take a 90 degree turn

01:08 and continue to drill horizontally,

01:11 parallel to the target rock layer.

01:12 This horizontal section of the well

01:14 can also travel for thousands of feet.

01:17 Now here's where the fracturing comes in.

01:19 First, you open up holes

01:20 in the horizontal section of the pipe.

01:22 Then you vigorously push a liquid cocktail

01:25 known as fracking fluid down into the borehole

01:28 under high pressure.

01:29 This fracking fluid is usually a mixture of water,

01:32 some chemical additives like acids to help dissolve the rock

01:35 and gels to thicken the fluid,

01:37 and finally, solid particles called propants.

01:40 We'll get to those in a second.

01:41 When the mixture reaches the horizontal section of the pipe,

01:44 it bleeds out through the holes into the surrounding rock,

01:47 and the extremely high pressure causes the rock

01:49 to form tons of little fractures or cracks.

01:52 Through these cracks,

01:53 the reserves of fossil fuels contained in the rock

01:56 can escape into the well

01:57 and be pumped back up to the surface.

02:00 What was once entombed in ancient rock

02:02 is now on the way to powering your car,

02:04 heating the water for your next shower.

02:06 And those propants I mentioned,

02:08 which are often just grains of sand,

02:10 help prop the cracks in the rock open

02:12 so the Earth's precious bodily fluids

02:14 continue to escape into the well

02:16 without the miners having to apply continuous pressure.

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