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Calcimator

Reservoir Volume Calculator

Estimate original oil or gas in place using volumetric method.

Inputs

acres
ft
%
%
rb/stb
%

Results

Original Oil in Place

20,854,499 bbl

Recoverable Reserves

6,256,350 bbl

Bulk Volume32,000 acre-ft
Pore Volume4,800 acre-ft
HC Pore Volume3,360 acre-ft
How to Use This Calculator
  1. Enter reservoir area (acres), net pay thickness (ft), porosity (%), and water saturation (%).
  2. Enter formation volume factor (bbl/STB for oil or mcf/scf for gas).
  3. Read original oil in place (OOIP in STB) or original gas in place (OGIP in Bcf).
  4. Apply recovery factor (%) to estimate recoverable reserves.
  5. Compare volumetric estimate against material balance results for consistency.

How the result changes with Formation Volume Factor

Formation Volume FactorOriginal Oil in PlaceRecoverable Reserves
1.1522,667,933 bbl6,800,380 bbl
1.5217,150,081 bbl5,145,024 bbl
1.9813,165,719 bbl3,949,716 bbl
2.3511,092,818 bbl3,327,846 bbl

What each input means

Drainage Area
Reservoir drainage area (640 acres = 1 section).
Net Pay Thickness
Net productive thickness of the reservoir.
Porosity
Average reservoir porosity.
Water Saturation
Irreducible water saturation in the reservoir.
Formation Volume Factor
Oil formation volume factor (Bo).
Recovery Factor
Expected ultimate recovery percentage.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Drainage Area = 640, Net Pay Thickness = 50, Porosity = 15, Water Saturation = 30 = 6 input(s) provided
  2. Calculate Original Oil in Place
    Original Oil in Place
    20854499 = 20854499
  3. Calculate Recoverable Reserves
    Recoverable Reserves
    6256350 = 6256350
  4. Calculate Bulk Volume
    Bulk Volume
    32000 = 32000
  5. Calculate Pore Volume
    Pore Volume
    4800 = 4800

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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