Borehole

A borehole is the generalized term for any narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water or other liquid (such as petroleum) or gases (such as natural gas), as part of a geotechnical investigation, environmental site assessment, mineral exploration, temperature measurement or as a pilot hole for installing piers or underground utilities. Also boreholes can be made for geothermal installations. As well as pumping petroleum from an underground well through a borehole, liquid or gas can be pumped into it, for that process, or for underground storage of unwanted substances., e.g. in Carbon capture and storage.