Sciencedaily- New Drilling Method With Fire And Flame In The Depth "In our experimental reactor we are able to ignite a flame underwater at a maximal temperature of about 2000°C.
The method is particularly suitable for hard, dry rock, normally encountered at depths greater than three kilometers. In such depths conventional drilling bits wear out much faster, and their frequent replacement, renders the conventional drilling techniques uneconomic: a 10 km borehole costs around 60 million US dollars.
In the case of the so-called "hydrothermal spallation drilling" method, however, the burner - drill bit wear is considerably less, because there is no mechanical contact with the rock. Read more at Sciencedaily
