Oil Reserves Calculator
Estimate recoverable oil reserves (in barrels) using the volumetric method with six reservoir parameters.
Use the Oil Reserves Calculator
Reservoir Parameters
Enter reservoir parameters and click Calculate to see results.
Stock-Tank Oil Initially in Place (STOIIP)
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Stock-Tank Barrels (STB)
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Million Barrels (MMSTB)
Recoverable Reserves
RF —%—
Stock-Tank Barrels (STB)
—
Million Barrels (MMSTB)
Formula Breakdown
Constant (7758 bbl/acre-ft)
7,758
Area
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Net Pay Thickness
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Porosity (φ)
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Oil Saturation (1 − Sw)
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Formation Volume Factor (Boi)
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Recovery Factor
—
STOIIP = 7758 × A × h × φ × (1 − Sw) / Boi
Recoverable = STOIIP × RF
Summary
The Oil Reserves Calculator applies the standard volumetric equation used in petroleum engineering to estimate stock-tank oil initially in place (STOIIP) and ultimately recoverable reserves. Enter reservoir area, net pay thickness, porosity, water saturation, formation volume factor, and recovery factor to get instant results in barrels and million barrels of oil equivalent.
How it works
- Enter the reservoir area in acres.
- Enter the net pay thickness in feet.
- Input average porosity as a percentage (e.g., 20 for 20%).
- Input average water saturation as a percentage (e.g., 30 for 30%).
- Enter the formation volume factor (Boi) in res bbl/STB.
- Enter the recovery factor as a percentage to get recoverable reserves.
Use cases
- Preliminary resource estimation for exploration prospects.
- Comparing recoverable reserves across different recovery factor scenarios.
- Quick sanity-check of volumetric estimates before detailed reservoir simulation.
- Teaching petroleum engineering students the volumetric method.
- Evaluating acquisition targets with known reservoir parameters.
- Sensitivity analysis on porosity and water saturation uncertainty.
Frequently Asked Questions
Last updated: 2026-05-29 · Reviewed by Nham Vu