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Old 07-07-2019, 07:15 AM
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What is the deepest human kind has dug into the earth?


I recall a quote that if the earth were an onion the deepest humans have dug is like same depth as peeling the outermost skin.

Is this still true?
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Old 07-07-2019, 07:20 AM
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12,262 meters.
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Old 07-07-2019, 08:20 AM
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12.262 km ÷ mean Earth radius 6371 km = ~0.0019

Which is less than a fifth of one percent. On an onion with a radius of say 5 cm, that's a depth of 0.095 mm. Less than a tenth of a millimeter. That corresponds to, at best, the onion skin, let alone any layers.
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Old 07-07-2019, 08:22 AM
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And earth has a mean radius of 6,371 km, which means that our deepest bore has penetrated 0.0019247 of the way to the center, or about about one fifth of one percent.

I don't know exactly how thick the single outer layer of an onion is, but the comparison seems about right to me.

Edit: Damn! Ninjaed!

Last edited by mhendo; 07-07-2019 at 08:23 AM.
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Old 07-07-2019, 08:59 AM
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What is so remarkable about the borehole is how it proved established scientific / geological theories wrong. (And remember this hole is even shallower than an apple skin). Here are two theories it proved wrong :

1. “There used to be common understanding among Western scientists that the crust was so dense 5km down that water could not permeate through it." - proven wrong because they found free water down there.

2. “Prior to drilling, scientists expected a granite-basalt boundary at around 7 kilometers. However, the project proves that this was not the case.”

https://www.techtimes.com/articles/2...-by-humans.htm
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Old 07-07-2019, 09:19 AM
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As far as the deepest hole humans have dug and can fit into at the bottom the winner is likely the Mponeng gold mine in South Africa.

ETA over 4 km deep.

Last edited by Marvin the Martian; 07-07-2019 at 09:20 AM.
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Old 07-07-2019, 06:09 PM
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largest man made excavation in the world is the Brigham Canyon Copper mine near Salt Lake City. Been digging there since 1906. 450,000 tons are removed every day.

https://en.wikipedia.org/wiki/Bingham_Canyon_Mine
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Old 07-07-2019, 08:44 PM
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Our deepest oil wells in these parts go about three kilometers, but that is not all straight down. Six or seven kilometers is about as deep as any bored well goes. On the plus side, we have done this hundreds or times.


This gives me hope we can get rid of our high-level nuclear waste.
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Old 07-07-2019, 10:23 PM
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A reference that a lot of people have actually experienced.
https://en.m.wikipedia.org/wiki/Grand_Canyon
Quote:
Grand Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile (6,093 feet or 1,857 meters).

Last edited by aceplace57; 07-07-2019 at 10:26 PM.
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Old 07-07-2019, 10:31 PM
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Wasn't this project the source of the urban legend about the scientists who drilled a hole so deep, they penetrated into hell?
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Old 07-07-2019, 10:41 PM
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Wasn't this project the source of the urban legend about the scientists who drilled a hole so deep, they penetrated into hell?

Yep.
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Old 07-08-2019, 04:56 AM
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Wasn't this project the source of the urban legend about the scientists who drilled a hole so deep, they penetrated into hell?
More like a suburban legend amirite
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Old 07-08-2019, 06:43 AM
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A reference that a lot of people have actually experienced.
https://en.m.wikipedia.org/wiki/Grand_Canyon
Yes, a well-known digging created by humans. It definitely qualifies.
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Old 07-08-2019, 08:31 AM
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Yes, a well-known digging created by humans. It definitely qualifies.

Just because Paul Bunyan dug it accidentally doesn't mean that it should be excluded!
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Old 07-08-2019, 08:43 AM
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Yes, a well-known digging created by humans. It definitely qualifies.

aceplace57 said reference. The man-made hole is six times as deep as something that people have actually experienced.

Last edited by Boozahol Squid, P.I.; 07-08-2019 at 08:44 AM. Reason: metric/english confusion
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Old 07-08-2019, 08:49 AM
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Our deepest oil wells in these parts go about three kilometers, but that is not all straight down. Six or seven kilometers is about as deep as any bored well goes. On the plus side, we have done this hundreds or times.


This gives me hope we can get rid of our high-level nuclear waste.
It is interesting that this XKCD shows the Deepwater Horizon rig drilled to more than 11,000m, but Wikipedia listed it as having drilled only to 10,683m. Either way, they are approaching Kola Borehole depths.
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Old 07-08-2019, 09:29 AM
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How the hell does oil end up that deep?
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Old 07-08-2019, 09:30 AM
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It is interesting that this XKCD shows the Deepwater Horizon rig drilled to more than 11,000m, but Wikipedia listed it as having drilled only to 10,683m. Either way, they are approaching Kola Borehole depths.
Don't forget the water column. Deepwater Gulf of Mexico wells have at least 1 km of water sitting on top of them, so the actually penetration into the earth is closer to 9-9.3km from the mudline for Macondo. It's less for other wells, as some of these are drilled in 1.5 to 2 km of water (or more). The 11km figure is a total depth referenced to mean sea level.

The ocean is itself an extreme engineering challenge but it usually doesn't "count" for many of these lists. But still, to approach Kola depths in that sort of environment is still a pretty big deal, engineering wise.

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How the hell does oil end up that deep?
Jurassic era rock. Used to be the geologists thought all the oil would just cook out and there would be nothing left, but that wasn't quite right.

Why Jurassic era rock shows up that deep is due to the Mississippi River. In other parts of the world, Jurassic era rock doesn't occur that deep. But the Mississippi River dumps a lot of sediment into the Gulf. Give that a million years or ten, and it adds up.

Last edited by Great Antibob; 07-08-2019 at 09:32 AM.
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Old 07-08-2019, 10:15 AM
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Originally Posted by Bijou Drains View Post
largest man made excavation in the world is the Brigham Canyon Copper mine near Salt Lake City. Been digging there since 1906. 450,000 tons are removed every day.

https://en.wikipedia.org/wiki/Bingham_Canyon_Mine
*nitpick*

Bingham, not Brigham. Copper was discovered there by the sons of Mormon pioneer Erastus Bingham while herding sheep. Brigham Young advised against mining because it would divert manpower from farming, which was needed more by the fledgling Mormon community. The name stuck as Bingham canyon, however.
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Old 07-08-2019, 04:09 PM
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How the hell does oil end up that deep?
Whatever the word is for layers of the earth folding in and out on each other, and plate tectonics.
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Old 07-08-2019, 04:21 PM
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Whatever the word is for layers of the earth folding in and out on each other, and plate tectonics.
Nah, there's no plate tectonics involved in that particular case. It's all on the North American plate. Not a whole lot of folding either.

It's literally just sedimentation and time.

That particular well (the one involved with the Deepwater Horizon) is part of the Mississippi River system. The river carries a lot of sediment along the way and dumps it in the ocean. While this is a continuous process, it happens a bit more after the spring floods. There have been literally millions of years' worth of sediments constantly dumped in the Gulf of Mexico. That eventually works out to sediment thicknesses of several miles.

Add in some salt from when the region was a near landlocked ocean that evaporated away. And some organic matter to generate oil, and Bob's your uncle. There is some trickiness for the temperatures and pressures that allow oil to generate instead of getting over or undercooked and in the local geology to provide adequate traps so the hydrocarbons don't just float off, but those conditions seem to have been met in this case.
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Old 07-08-2019, 04:23 PM
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Talking about reaching hell made me think of the Darvaza gas crater. But apparently it's only 65 feet deep.

They'd tell us if it ran out of gas and went out, right?
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Old 07-11-2019, 02:55 AM
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Originally Posted by Marvin the Martian View Post
As far as the deepest hole humans have dug and can fit into at the bottom the winner is likely the Mponeng gold mine in South Africa.

ETA over 4 km deep.
Of course, this starts at 1550m elevation, so it might not be the deepest mine (measured from Earth's core)

Even the ultimate borehole, the Kola Superdeep Borehole , got less than a third of the way through the crust at a depth of 12200m (starting at about 230m, so 12km down). The crust thereabouts is only about 35km thick, so it was still less than 1/3rd of the way through.

But yes, we have barely scratched the top 1/10th of the Earth's crust, and the whole of the crust (average 100km deep but varies greatly) is only about the top 1.5% of the Earth.

If you want to reach the core you need to go a lot,lot,lot deeper.

Last edited by MarvinKitFox; 07-11-2019 at 02:57 AM.
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Old 07-11-2019, 05:36 AM
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As far as the deepest hole humans have dug and can fit into at the bottom the winner is likely the Mponeng gold mine in South Africa.

ETA over 4 km deep.
Weird things happen when you go that deep. When you climb a mountain, the ambient air pressure drops to below that of sea level; but when you go down in a mine, the ambient air pressure increases to above that of sea level. When you go down to 2500m below sea level (4 km below the 1550m mine entrance level), the ambient pressure is 19.7 psi. When you get that far, the rock is hot, just from geothermal heat; in that mine, the rock is reportedly at around 150F. If you think you can cool it by blowing air down the main shaft, think again. When you compress air, it heats up (this is why diesel engines work). So when you force 70F air from 1500m above sea level down to a depth where it's at 19.7 psi, the temperature increases to...surprise, about 143F. You won't get any cooling effect at all. According to the Wikipedia page, cooling is instead achieved by pumping ice slurry down from the surface.

Another fun occupational hazard is rock burst. the rock at that depth is under crazy high pressure from all sides. That is, until miners arrive and relieve the pressure on one side. At that point, the exposed rock can literally explode outward toward the miners - in some cases, killing them. Here is a series of very small rock bursts in a tunnel, just big enough to take your eye out. Now imagine one that fires hundreds (or thousands) of pounds of rock at you.
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Old 07-11-2019, 07:20 AM
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Of course, this starts at 1550m elevation, so it might not be the deepest mine (measured from Earth's core)
Given the large difference between equatorial radius and polar radius: 3,963 miles (6,378 kilometers) vs 3,950 miles (6,356 km) or 13 miles (22 km) less. I don't think standing at the North Pole qualifies as being extremely deep just because you're closer to the core than just about any underground site.
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Old 07-11-2019, 12:08 PM
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If you just want to get down as deep as you can, check out the Soudan Mine in northern Minnesota. A really cool old iron mine converted to a state park. It will get you down to 713m. It takes a long time to get that deep. Cool stuff if you are interested.
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Old 07-11-2019, 12:23 PM
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Is there a level at which scientists would expect to find high concentrations of gold?
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Old 07-11-2019, 01:04 PM
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Is there a level at which scientists would expect to find high concentrations of gold?

The inner core.
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