Drilling is the process of constructing a mine mostly of a cylindrical form (shot-hole, well, mine shaft) by means of rock disintegration at the downhole with spalls removal. Drilling is mainly performed in the Earth crust.

There are the following drilling techniques according to the type of rock destruction:

  • mechanical (rotary, percussion, percussion-rotary and rotary-percussion drilling);
  • thermal (flame-jet, plasma);
  • electric;
  • explosive;
  • hydraulic.

Drilling is performed for survey and exploration of fields, study of the Earth crust geological structure, mineral resources extraction from the subsurface, performance of explosive operations, drainage and ventilation of underground facilities, construction of pile foundations, etc.

During drilling, the downhole rock mass is usually destructed (non-core drilling). During drilling with core sampling, only the annular space near wellbore walls is destructed, and the inside rock column is recovered in an undisturbed state for evaluation of the field geological structure.