A wellbore is any hole drilled for the purpose of exploration or extraction of natural resources

Natural Resources

Natural Resources is a soul album released by Motown girl group Martha Reeves and the Vandellas in 1970 on the Gordy label. The album is significant for the Vietnam War ballad "I Should Be Proud" and the slow jam, "Love Guess Who"...

 such as water, gas or oil where a well may be produced and a resource is extracted for a protracted period of time.

It is often used interchangeably with drill hole or borehole

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 or gases , as part of a geotechnical investigation, environmental site...

 though typically a "borehole" is referred to in ore

Ore

An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....

 mining

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

, exploratory drilling, or pilot hole

Pilot hole

A pilot hole is a smaller hole drilled into a material prior to a larger hole being drilled, widening the hole to the desired width. Drilling a pilot hole prevents a larger drill bit from slipping on the material - a potential safety hazard, as well as an increased likelihood of the work being...

s for installing pier

Pier

A pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...

s or underground utilities, or any other of a number of single use hole drilling.

See Drilling rig (petroleum)

Drilling rig (petroleum)

This article lists the main components of a petroleum onshore drilling rig.Offshore drilling rigs have similar elements, but are configured with a number of different drilling systems to suit drilling in the marine environment....

for a diagram of a drilling rig.