58 Pa. Stat. § 1002
The following words and phrases when used in this act shall have the meanings given to them in this section unless the context clearly indicates otherwise:
"Department." The Department of Environmental Protection of the Commonwealth.
"Operator." A well operator.
"Unconventional formation." A geological shale formation existing below the base of the Elk Sandstone or its geologic equivalent stratigraphic interval where natural gas generally cannot be produced at economic flow rates or in economic volumes except by vertical or horizontal well bores stimulated by hydraulic fracture treatments or by using multilateral well bores or other techniques to expose more of the formation to the well bore.
"Unconventional well." A bore hole drilled or being drilled for the purpose of or to be used for the production of natural gas from an unconventional formation.
58 P.S. § 1002