Rocks are very weak in tension, despite being very strong in contraction. It's the reason you can break rock with a hammer or the reason ancient quarries were able to work by pouring water on wood pegs in rocks. It's also the reason concrete needs rebar to reinforce it (steel is very strong in tension, so the two combined are exceptionally strong). Keeping a hole open requires strength in tension as well as strength in compression.
Drilling mud accomplishes this by being roughly the same density as the rock, so it offsets the stresses that are trying to close the borehole that steadily increase with depth due to the increasing amount of rock above. Drilling mud keeps the borehole open until you can put in casing to support it.
This is exactly the same reason why it's difficult to build a submarine that can go to very large depths in the ocean. To put up steel walls (casing) to keep it open, you have to stop drilling and cement in casing - you can't do that as you drill. So drilling mud is a key part of being able to drill efficiently. Otherwise, you'd need to stop every few tens of meters and spend _days_ setting casing before being able to drill again.
Regardless, there is nowhere on earth where things are homogenous over very long distances. Simply put, even relatively uniform rocks can have very significant variations in physical properties. Many relevant properties (e.g. permeability - how well fluids can move through) vary over _tens of orders of magnitude_ naturally. So "uniform" can still mean "only varies by a few orders of magnitude". There are places where you can reasonably avoid non-silicates, but you're going to hit tons of other issues due to fundamental heterogeneity.
Sorry, I think not. Neat idea, but there's big holes in that in practice.
Can types of drill bits (heads?) be swapped out? So use the super diamond bit to get started, then switch to Quaise's maser once you reach granite.
Just guessing. Am noob. Am just trying to follow along.
eg Most recent Volts podcast episode: An update on advanced geothermal w/ Tim Latimer of Fervo Energy.
So yes, you could swap the two out. But we already have bits that are good at drilling hard rock (granites, etc) they're called tricone bits. They more so crush the rock than cut it. And they look badass.
I can see this being a lot like conventional drilling to a point with several bit trips or casing runs necessary until you reach a point where the borehole tends to collapse due to overburden pressure, especially in overpressured environments where well control is critical, and it is no longer possible to trip out and run casing before the borehole collapses in the newly drilled interval.
What happens if your proposed well encounters salt or other evaporites? A lot of questions could use answers and those answers only come from poking holes in the ground so maybe if they throw enough money at it they can determine where this method can be useful. That would be the most valuable result of all this.
This looks useful for near surface stuff but for ultradeep wells looks like it needs some experimentation.