Worked on a core drill rig that that did 2200m core drilling, worked a number of holes from 100-2200m on a few different types of surface rigs. Stuff gets weird when you get deep >1500m. Runs take ages, bit changes can take an entire shift. The structures in the rock can come out looking like a picture in space (black base littered with color). Hitting 10 miles (16km) would be epic. Something like 100 ton rod string hanging at BQ size. Insane.
"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 seven kilometers (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"
It's a fascinating project and a real shame funding was cut off. The deep borehole in Mexico was also stopped due to lack of funding.
Maybe they can use global warming dollars to renew these deep borehole projects around the world, as I suspect there is new geological science to be discovered as observations appear to deviate from theory:
"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. The unexpected decrease in density, the greater porosity, and the unexpectedly high temperatures caused the rock to behave somewhat like a plastic, making drilling nearly impossible"
That's strange, wouldn't a plastic be much easier to drill into? Maybe it required a different kind of drill head that they had no way of getting down there within budget?
The problem is the pressure. Even steel gets soft when it gets hot enough and with the pressure its like trying to push folded toilet paper through cake dough.
I don't know. I am afraid that article is bullshit. So it doesn't make sense to give an answer to your question.
This aside, let me give some examples about geothermy. In Iceland and in New Zealand it is possible to get hot water from the ground without deep drillings. In Switzerland there was a failed project about geothermy, because the drill down to the granite bedrock at a depth of about 2700 m and deeper caused an earthquake. People in Basel are very sensitive because it was a location of an huge earthquake 1356.
In other words, we don't need to drill so deep at all. YAGNI.
Another idea might be to have solar panels or wind turbines up top and geothermal below. Both could use molten salt storage, from which energy is generated on demand.
This way, any heat generated from geothermal would not be wasted.
It's just a matter of whether the economics of drilling and maintaining the bore hole would be worth it.
The longest wells are already close to 10 miles, but it is mostly horizontal. My understanding is going deep you eventually hit hot rock which has a clay like texture and isn’t amenable to drilling.
Core drilling is quite different from well drilling which would be used in this case.
Yes, and it's hot enough that your drill starts heating up and getting the same texture if you're not cooling it aggressively, which is hard to do so deep down.
I'm gonna say no. You'd be going up against the compressive resistance of the ground. At depth where the pressure is already high, you won't be able to compress the ground much further even with the extreme force of a nuke, and most of the compression that you do achieve will just bounce back a moment after.
At shallow depths it is possible for matter to be pressed to the side, because in addition to being lower pressure and more compressible, matter can be displaced sidewards and up. I imagine shaping the nuke will make a differently-shaped cavern, but still just a cavern.
The nature of the fireball means you can't really use any type of physical structure to shape it... though I guess multiple miles of rock would work too, but it won't be in the desired direction[1]
so it's possible, though questions/problems arise such as: the cavity created by the explosion has a high chance of collapsing, the energy might trigger earthquakes, etc.
though smaller scale shaped charges "might" work to push rock out of the way, if the well segments can be advanced down safely into the created space.
Nah no photos allowed as it was gold core work. You basically see if a mine is going to strike gold over next few years before everyone else does (think stock market performance impacts). Too much risk of data exfiltration given they had enough of a problem with word of mouth.
Because these results can show more information than just a single bit?
The result might not just show “not worth digging” vs “worth digging”, but something like “the gold will flow for 4 years and then only trickle for 2” vs “the gold will flow for 8 years and then nothing”.
This ^^^ We weren't drilling core for todays mining. We were sampling to see if the mine was viable years ahead and where underground would be directed over the coming months. The deeper you are or the further you are from the pit or underground path the further into the mines future you are looking essentially.
Edit: Also these are big publicly traded companies, drill reports get added onto forecasts for mine productivity which affects stock price projections & profit projections.
You wouldn't be able to know how many years exactly from the core drilling visuals, for that you'd need to assay the cores for the grades, build a mining block model and then develop a mining plan from that. It's more of a qualitative "oh dam they've struck gold a lot of it" sort of thing that would move markets. Disclosures to markets in mining need to be done publically and with proper backing of data, legacy of BreX salting their core samples and reporting the motherload of gold mines.
What do these bits look like? How wide are they? How does the drilling work, are they hollow and the material goes in the middle, which you then pull up every now and then? Do they come in sections (how long) and you just keep putting in more?
Sorry for many questions just can't find much info on actual field truth (just generic info on theory of operation).
So we drilled core for gold. There are two main types of drilling RC and diamond core. RC is like a pneumatic hammer system i didnt work with those so cant say much about them (they recover a dust pile as their sample type, diamond core pulls out preferably a long cylinder core sample that has orientation marked on it (e.g. north).
Diamond core drilling tho is basically a cylinder shaped drill bit attached to a hardened drill rod that is attached to a rod string (groups of 3m pipes). Everything is basically done in 3m lengths, mostly for transport reasons. When your drilling you work with the rods in bundles of 3 so 9m lengths. I worked mostly on UDR 1200's and a prototype surface rig that there were like...3 built? partnership between a few big companies. That rig was the one that could do (estimated) up to 3000m or so. Deepest I worked on was 2200m. Drill bit sizes if your interested in looking them up that we worked with are BQ,NQ,HQ,PQ. So external diameters ranging from 60mm with bq (core size of 36.5mm) to PQ @ 122mm ext. and 85 ID. We worked all manual by hand so PQ with a drill barrel weighing like 50kg was our limit. Shaking core from 3m HQ drill rods nearly broke me the first time I did it.
The drill barrels have a inner tube that is the core holder/lifter that hangs like a few mm from the spinning bit at all times while drilling, these are 6m long. After you have drilled 3m, you clamp the rod string so its hanging from the drill rig and add 3m until you have preferably 6m drilled. Drilling stops, you pull back on a wireline that is holding the core tube to engage the internal clamps on it and haul up your 6m of core. A empty tube gets sent back down, you add another 3m rod to the string and repeat the process. While this happens the full core tube is orientation marked, shaken out and cleaned and re-assembled as it comes out of the hole in core trays. ^^^^ Everything above is if things go to plan. Rough ground, broken bits, hard ground, loss of water return all kinds of things can cause problems and make runs stop, go short, loose rods, drop core, require bit changes, cause equipment to overload and break so on. Been a few years since I did it but I do kind of miss the work.
https://www.youtube.com/watch?v=DUMftmjpdNg This is a video of after a bit change. they are pushing rods back down the hole to hit the point where drilling stopped. They are moving real slow. 111 rods roughly to 1000m. Worst shift I had was 16 ton of rods moved. >1000m down, started shift pulling rods for a bit change, bit snapped a tooth after we got it back down in under 5m of cutting and had to come straight back out. Hell of a night. If your lucky you have 3 to a rig (driller and two offsiders) if your unlucky its just 2 on a rig. No breaks. You eat while you drill.
Dam, didn't think I'd see another mining person on hackernews. Exploration geology that far down is wild. Was it core sampling all the way from grade or only in mineralized zones?
Core sampling the whole way. Outskirts of jundee at wiluna. Punched a few holes down the side of the pit while I was there and the deep holes were for underground to work out where they were going. Most target zones 800-1200. I got lucky as the drillers I offsided with were absolute guns so we got the hard stuff. Best day we cracked >100m in our 12 hours and cross shift got 80m. 22mins was out fastest 6m off memory. That was shallow work tho, deep holes can take 45m just to pull a core tube.
I don't drill any more but do kind of miss the work.
The drilling fluid/mud is pumped down the center of the string and flows back up the sides of the bore hole. The material removed comes up with the drilling fluid.
The drill string is a chain of threaded pipes.
There is tons of good information online, just search for oil well drilling on YouTube.
This stuff is nuts, https://amcmud.com/product/amc-cr-650/
Have sent pallets of the stuff down hole. Few 500ml scoops of that and you can turn 5000l of water into some crazy thick mud for bringing up heavy cuttings. Worst experience tho copping a face full of dust when dosing it tho, gets in your eyes. Takes a ridiculous amount of water to wash past the thickening point and get it out.
I once had the task of measuring powdered dye for industrial soap. A coworker told me to make sure and tamp down the can. Turns out tamping the can kicks up just enough dust that I had blue snot for a week. Not an OSHA approved practical joke, but funny nonetheless.
