1.
n. [Geology, Shale Gas]
An umbrella term for oil and
natural gas that is produced by means that do not meet the criteria for conventional
production. What has qualified as unconventional at any particular time is a complex function of resource characteristics, the available
exploration and production technologies, the economic environment, and the
scale,
frequency and duration of production from the resource. Perceptions of these factors inevitably change over time and often differ among users of the term. At present, the term is used in reference to oil and gas resources whose
porosity,
permeability, fluid trapping mechanism, or other characteristics differ from conventional
sandstone and
carbonate reservoirs. Coalbed
methane, gas hydrates,
shale gas, fractured reservoirs, and
tight gas sands are considered unconventional resources.