Well

A hole drilled into the ground, mostly by rotary rigs, in which a drill bit, which actually cuts the rock, is turned on the end of a drill string, made up of lengths of hollow steel pipe which are added to the string as the bit drills deeper into the ground. Wells have various descriptions depending on the stage of the production process at which they are drilled. Exploration wells are drilled to discover if gas (or oil) can be found; Evaluation or appraisal wells are drilled to obtain more information about a previous discovery; Development wells are drilled to produce gas from a field which is being developed, and are called Producing wells when the field enters commercial production.