The estimated volumes of hydrocarbons be it fluid, liquid and or gas that are anticipated to be commercially recoverable and marketable from the given date under existing economic conditions.


Known reservoirs that can be estimated with reasonable certainty. They are considered proved if commercial profitability of the reservoir is supported by actual production values. The area considered proved is defined by drilling and fluid contacts. If undrilled then geological and engineering data can be used to determine the areal spread.

You can also have proved undeveloped reserves assigned to undrilled areas, so long as the locations are offset from proven well indicating a commercial formation, are known to be within productive limits of a formation, conform to existing well spacing and will be developed in the future.


Based on geological and or engineering data, but technical, contractual or regulatory uncertainties mean it can’t be classed as proved.


Attributed to known accumulations and less certain to be recovered. It indicates reserves:

  1. That exist a reasonable distance from proved reserves
  2. That exist in productive formations but lack definitive tests
  3. In a part of a field that is part of a productive formation but separated by a fault
  4. To be obtained by IOR methods
  5. That can be produced by primary recovery methods
  6. Determined by infill drilling
  7. That are dependent on workover or such intervention


Associated with known accumulations that are less certain to be recovered than probable.

   Developed Reserves

Expected o be recovered from completed intervals, it include production from IOR methods

  Non-Producing Reserves

Shut In and behind pipe reserves. Reserves expected to be recovered after completion, or those completed but not producing or those that may require further completion work or re-completion.

  Un-developed Reserves

Expected to be recovered:

  1. From proposed wells or new wells on undrilled acreage.
  2. By the extending of existing wells into different reservoirs.
  3. In due course depending on financial resources or the building of suitable infrastructure to facilitate the production.

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