today
State of the art in deep drilling
Deep drilling so far has depended on using conventional, rotating drilling methods - through mechanical dissolving and removal of the rock with carbide heads. In doing so, at the least the pressure and in part also the shear stress of the rock have to be overcome.
A special liquid - the drilling fluid - then carries the cuttings up to the surface overnight. With increasing temperatures (approx. 100 °C/212 °F per 3,000 m drilling depth) and growing hardness of respectively the physical pressure in the rock, the abrasion and wear on the drill head increases exponentially.
Due to the increasing wear on the drill heads these have to be changed approx. every 25 hours. This causes considerable time delays (standstill and round trips) and blockages in the borehole, due to, among other things, metal residues.