Borehole

A borehole is a narrow shaftdrilled into the ground, either vertically or horizontally. Boreholes range from shallow holes just a few feet deep to engineered shafts extending hundreds or even thousands of feet underground. A borehole may be constructed for many different purposes, including the extraction of water ( through drilled wells and tube wells), other liquids (such as petroleum), or gases (such as natural gas). It may also be used for geotechnical investigation, environmental site assessment, mineral exploration, temperature measurement, as a pilot hole for installing piers or underground utilities, for geothermal installations, or for underground storage of unwanted substances, e.g. in carbon capture and storage.