At least they provided this tidbit:

Engineers also discovered, as they plowed past the first 14,800 feet (4,511 meters), that the rock had much more porosity and permeability. That, paired with the extremely high temperatures, made the rock behave more like a plastic than a solid, rendering drilling virtually impossible.

…howstuffworks.com/…/kola-superdeep-borehole.htm#…

Plastic Earth confirmed.