Part of total current Hydrocarbon In Place (HCIP) in petroleum reservoir which can be economically recovered to the surface under specific FDP by the end of its producing life. 

It comprises comprises:

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The volumetric value of HCR in Hydrocarbon Reserves (HCR) in NTP conditions is given by STHCR represented by two numbers: { Stock-Tank Oil Reserves (STOR) , Stock-Tank Gas Reserves(STGR) }

The maximum recoverable volume of Hydrocarbon Reserves (HCR) is called Estimated Ultimate Recovery but normally it explicitly refers to Estimated Ultimate Oil Recovery (EUOR) or Estimated Ultimate Gas Recovery (EUGR).

The percentage which recoverable reserves STHCR constitute of the total of Estimated Ultimate Recovery taken from the total Surface Tank Hydrocarbon Initial In Place (STHCIIP) is called  is called Estimated Ultimate Recovery Factor (EURF).

Unlike STHCIIP, which is purely geological concept, the STHCR and corresponding RF depend on the parameters of FDP based on reserves complexity, Hydrocarbon Initial In Place (HCIIP), which is a geological category, the concepts of Estimated Ultimate Recover and current Hydrocarbon Reserves depend on FDP and Petroleum Production specifics (recovery method, recovery duration, surface logistics, market conditions and economics). 

There are different ways of classifying hydrocarbon reserves based on their volume and structurethe Hydrocarbon Reserves which provide the primary insight into the size, uncertainty and structure of the Hydrocarbon Reserves.

See Also

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Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology /  Petroleum Reservoir / Petroleum Reservoir Fluids / Petroleum Hydrocarbon / Hydrocarbon Initial In Place (HCIIP) / Hydrocarbon In Place (HCIP) 

[ Exploration ][ Booking Reserves ] [ Hydrocarbon Reserves Classification ] 

[ Oil Reserves (OR) ] [ Gas Reserves (GR) ] [ Estimated Ultimate Recovery Factor (EURF) ]