Unconventional gas

Unconventional gas is natural gas obtained from sources of production that are, in a given era and location, considered to be new and different. Sources that are at times considered to be unconventional include the following:
As noted by the International Energy Agency (IEA) in 2013 regarding unconventional oil, what is conventional vs. unconventional changes over time as technologies and economies change. Certainly, this applies to unconventional gas as well.
Natural gas, whether conventionally produced or not, has been considered to be an unconventional source for oil production.