Unconventional (oil and gas) reservoir

[3] Two world wars, followed by huge economic growth resulted in surging demand for cheap portable energy,[4] while the availability of new conventional oil and gas resources declined.

[9][10] The distinction between conventional and unconventional resources reflects differences in the qualities of the reservoir and/or the physical properties of the oil and gas (i.e. permeability and/or viscosity).

Conventional oil & gas accumulations are concentrated by buoyancy driven aquifer pathways into discrete geological traps, which are detectable from the surface.

In general, the technical and commercial risk associated with discrete conventional reservoirs can be reduced using relatively inexpensive remote techniques such as reflection seismology and extracted with relatively few appraisal and development wells.

The oil and gas in unconventional reservoirs are generally low density resources, frequently trapped in the rock by strong capillary forces incapable of flowing naturally through buoyancy.

The artificial transfer of heat and pressure require the use of large volumes of fresh water creating supply and disposal issues.