Drilling is the method of penetration of the cylindrical mine workings — boreholes.

A borehole is characterized by relatively small cross-section 76-190 mm in diameter and often of considerable length (depth). Elements well is:

• The mouth is the beginning of the well
• Bottom — the bottom of the well
• Cylindrical surface of the borehole wall.

Drilling is carried out using special drilling equipment and consists of several processes:
• Drilling of rocks on the bottom, which makes the promotion of bottom — deepening of the borehole.
• Cleaning the well bottom from the destroyed rock.
• Coring (if necessary).
• Mounting of the borehole walls.
• Production of tripping operations, replacement of worn out rock cutting tool in conducting research in the wells, mounts the walls of the borehole.

During rotary drilling of the first two processes — the destruction of the breed and cleaning the well — aligned in time. The casing is used for drilling in bad rock. In wells make a number of observations and studies: measure the water level, flow rate, pumping water to clean it, explore walkable breed methods borehole Geophysics (logging).

In the Leningrad region mainly drilled exploratory-exploitation wells for water supply of private houses and cottage settlements.