The borehole has now been welded shut and is surrounded by the ruins of the project. The actual borehole itself is pretty unassuming for something that goes twelve kilometers into the Earth's crust: https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole#/media...
How stable are abandoned holes like that? I would imagine that at those temperatures and pressures, the rock would slowly flow and refill the hole after a while.
It got to 180C at the bottom. That's nowhere near hot enough to melt rock. Not sure about the pressure though. I get the feeling though that rock tends to either stay put or shift all at once (like an earthquake).
Not hot enough to melt, but heat definitely reduces structural integrity of materials. And pressures on the rock so deep are immense. This article linked from Wikipedia seems to confirm that the hole tended to close itself when they were drilling:
"At that level of heat and pressure, the rocks began to act more like a plastic than a solid, and the hole had a tendency to flow closed whenever the drill bit was pulled out for replacement."
"When the well reached a mark of about 12,000 meters, scientific equipment recorded sounds resembling the cries and groans of thousands of martyrs emanating from the depths."
I think we've crossed the line from documentary to creepypasta.
It's kind of hard to believe how our species has managed to explore furthest of planets, stars and galaxies while just drilling 7.62 miles through the crust of the very planet we exist on and "dominate" [0] -- a testament to how challenging crust drilling can be, right on par with exploring deepest parts of Earth's oceans.
I don’t find it surprising at all that we found traveling through a vacuum easier than traveling through solid granite.
Imagine how much mass that drillbit had to go through and now translate that into the density of interstellar medium. You could probably travel half way across the galaxy before your space ship went through as much matter as that drill.
> a testament to how challenging crust drilling can be,
> right on par with exploring deepest parts of Earth's oceans.
except if you read the footnotes it says that Exxon beat the world's record for length of borehole in 60 days. Sounds like drilling in the crust is NBD, been doing it for years, the innovation is all in how to make it turn and twist and do so on time and under budget.
My sense is that it's just not economically rational to drill a hole straight down for no other reason than you want to see how far it can go. Why bother? But it doesn't seem at all to be a technical problem.
This article lead me down the rabbit hole to the page for Mud (drilling fluid) engineer, which might be one of the most vandalized articles I've ever seen (# vandalizing edits/total edits)
glad I'm not the only one who went down that hole (pun very much intended) and started watching videos about the Reelwell Drilling Method and horizontal displacement techniques.
Really interesting experiment. Since the temperature was greater than expected would that have any bearing on being able to use bore holes for geothermal power?
I believe they are trialling this in a few places but I can't help but think that a hole that small (circumference wise!) could be easily implemented and potentially used as an energy source
Continental crust is between 20 miles deep and 50 miles deep, this borehole 'only' managed to get to 7.4 miles deep - we've still go a long way to go before we get to The Lost World of the Dinosaurs.
I would like to understand why drilling stopped at the depth it did. Was it something to do with the material at that depth, something to do with the drill, some other factor?
>Because of higher-than-expected temperatures at this depth and location, 180 °C (356 °F) instead of the expected 100 °C (212 °F), drilling deeper was deemed unfeasible and the drilling was stopped in 1992. [0]
>I would like to understand why drilling stopped at the depth it did. Was it something to do with the material at that depth, something to do with the drill, some other factor?
At that depth, pressure and temperature, the rock behaved like plastic and not solid and the drill was ineffective since the hole would immediately close as they pulled the drill. So they had to give up.
I'm no geologist, but 180C doesn't sound hot enough to make rock behave like plastic.
Ninja-edit: It looks like the temperature / pressure isn't so problematic because of rock moving around, but instead to do with cooling the drill bit (which you can imagine gets quite hot). If temperatures increase, cooling the bit becomes difficult, and at high-pressures, pumping the coolant around becomes very difficult.
> Did they make any special geological discoveries?
[From the Wikipedia article:] To scientists, one of the more fascinating findings to emerge from this well is that no transition from granite to basalt was found at the depth of about 7 km (4.3 mi), where the velocity of seismic waves has a discontinuity. Instead the change in the seismic wave velocity is caused by a metamorphic transition in the granite rock. In addition, the rock at that depth had been thoroughly fractured and was saturated with water, which was surprising. This water, unlike surface water, must have come from deep-crust minerals and had been unable to reach the surface because of a layer of impermeable rock.
Another unexpected discovery was a large quantity of hydrogen gas. The mud that flowed out of the hole was described as "boiling" with hydrogen.
> Did they find any precious metals, etc.?
These concentrate in veins, so the single borehole would not be the best way to find out. They were probably recorded in mud logs somewhere.
> is it possible to measure the depth of the hole using a laser
Holes like this are very rarely totally straight as the geology likes to manipulate the drill string as it descends. Whilst this won't be a true deviated well (due to the research goals) I'd be very surprised if there's a vertical hole.
Ah, indeed, the dreaded question "How hard can it be?" and its rarely-spoken assumption "that looks simple from my armchair". Well...most of the low-hanging fruit has already been picked, and things that look simple are chock-full of those pesky details that are handwaved away in the birds-eye view. "Just use the right technology," and you have flying cars, strong AI, self-driving vehicles, space elevators and whatnot. How hard can it be?
Geothermal isn't really sustainable (in the long, long term). The heat is built up due to some special geology, think an insulating blanket. Once you use this heat to make electricity you lower the temperature of the rock and it takes a very, very long time to warm up again.
It is sustainable enough under any reasonable scenario, and will in effect mainly just harness some of the heat that already dissipates.
As for for rewarming the rock: if the strata that were porous and water filled were found at the appropriate levels this problem would be reduced. One would not need to hydro-shear the rock is normal in EGS plants nowadays (with some inconvenient side-effects - see Basel)[0]
I like a lot of PBS's content. Like physics girl, and what the physics. Engineer Guy also produces good content. MinutePhysics is also a good choice. As for math related topics, I love 3Blue1Brown.
In general I find science journalism lacking.
My biggest problem with SciShow is that it's a bunch of people who lack a true science background commenting on topics. I really don't think that they do their due diligence in reporting, there's been cases where they present incorrect findings, and hype up the physically impossible.
Cool, thanks for the recommendations. I gravitated to SciShow because was produced by Hank Green, who's other YouTube offerings I really enjoy. I guess it's a lesson to be more critical with my sources, regardless of the author's previous work.
Looks like the drill tower used to be there, maybe they just wholesale lifted the proprietary drilling rig out of there. I'm sure they had to invent a thing or two about drilling to do this research.
You fear to go into those mines. The Dwarves dug too greedily and too deep. You know what they awoke in the darkness of Khazad-dûm... shadow and flame.".
Most of them either were educated in (old, pre-USSR) Russia, or by people who had Russian education. Once the generation changed, people educated in/by Soviet system achieved... well, you've listed it.
Or will you suggest that a country where communism is "scientific" and whole areas of science can be banned is actually capable of developing homegrown science? This is laughable on its face.
You could have read the entire sentence -- while there were some remnants of the pre-revolution education teaching in schools, there were Nobels. Once they had died out, and the new generation educated in Soviet schools by Soviet-educated teachers appeared, Nobels went away.
I guess you have never heard about genetics? It's generally considered to be a science. Except in USSR where for a long time it was officially termed a pseudo-science and a call-girl of imperialism.
What you're talking about is Lysenkoism and it was mostly during Stalin rule. Later Soviet biologists actually criticized Lysenko and the whole anti-genetics stance. Similar movements also happened in Western science, like Social Darwinism for example.
Social Darwinism or anything like that has never been appointed as the one and only TRUE THING with scientific opponents sent off to labor camps.
Also, soviet high elementary through high school education was... I'm not sure if "better" is the correct word, but it certainly taught more science than American schools do, if we compare average American school with a good school in Moscow, Leningrad, or similar large cities.
College level education in USSR was nowhere near as good as American -- you can't have good education if teaching people to think for themselves is physically dangerous.
[Source: I attended better than average schools and a decent college in Moscow]
There's a well known urban legend about the borehole that they stopped drilling when a scientist lowered a microphone into the hole. When they played back the recording they heard terrible screams, supposedly from people trapped in hell. Nice campfire story!
