Fracking explained
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.