the term refers to the extraction of shale gas, coal-bed methane/coal seam gas (CBM/CSG) and “tight oil.” A scaled-up form of hydraulic fracturing (high volume), involving injecting fluids under high pressure to crack the rock, is often used to release hydrocarbons during unconventional oil and gas extraction.

Unconventional oil and gas extraction is a complex process, involving pad construction, well drilling, casing, stimulation (often including but not limited to hydraulic fracturing), extraction, waste disposal, well plugging (or failure to do so) and abandonment, as well as associated infrastructures such as pipelines, storage facilities, compressor stations and export terminals.