Subsurface reservoir containing petroleum fluids.
Its structure and properties are described by Depositional facies, Lithological facies and Petrophysical rock properties and petroleum fluid properties.
The size, structure and complexity of Petroleum Reservoirs are normally characterized by the generally accepted metrics on Reserves Classification.
The typical forms of the fluids which can be found in Petroleum reservoir are called Petroleum reservoir fluids.
See Also
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology