Enter Parameters
Example Data Table
Use these values to test the calculator and confirm your workflow.
| Case | OOIP | Np | Nr | EOR | EUR | RF Current | RF Ultimate |
|---|---|---|---|---|---|---|---|
| A | 1,200,000 | 180,000 | 240,000 | 50,000 | 470,000 | 15.00% | 39.17% |
| B | 850,000 | 95,000 | 120,000 | 0 | 215,000 | 11.18% | 25.29% |
| C | 2,500,000 | 410,000 | 0 | 0 | 410,000 | 16.40% | 16.40% |
Numbers above are illustrative. Always validate field and laboratory estimates.
Formula Used
The calculator uses standard recovery factor relationships based on volumes.
- Estimated ultimate recovery (EUR):
EUR = Np + Nr + EOR - Current recovery factor:
RF_current = (Np / OOIP) × 100 - Ultimate recovery factor:
RF_ultimate = (EUR / OOIP) × 100 - Remaining to reach EUR:
Remaining = max(EUR − Np, 0)
How to Use This Calculator
- Enter OOIP as the original in-place volume estimate.
- Enter Np as cumulative produced volume to date.
- Optionally add Nr for remaining recoverable volume.
- Optionally add EOR for incremental recovery uplift.
- Select a unit and precision, then press Calculate.
- Download CSV for spreadsheets or PDF for reporting.
Recovery factor meaning for engineering decisions
Recovery factor (RF) expresses the portion of original in-place volume that is produced. It links geology, drive mechanism, and operating strategy into a single performance indicator. RF is dimensionless and typically reported as a percentage. In screening studies, RF helps compare fields of different sizes without being biased by absolute volumes. For liquids, RF is often computed against OOIP; for gas, it can be computed against OGIP when volumes are consistent.
Input preparation and unit discipline
Reliable RF starts with disciplined inputs. Use one unit system for OOIP, cumulative production, remaining recoverable, and incremental recovery. Convert before entry, not after. If OOIP comes from volumetrics, document porosity, saturation, and net-to-gross assumptions. If production is allocation-based, confirm shrinkage and stock-tank conditions. Small unit mismatches can shift RF by several percentage points and mislead decisions. If any input is unknown, enter zero and note the gap, then update as data improves quickly.
Interpreting current versus ultimate recovery
Current RF reflects what has already been produced: Np divided by OOIP. Ultimate RF uses the expected total recovery, so EUR is a better planning metric than Np alone. When Nr and EOR are included, the calculator reports an “ultimate” view and a remaining-to-EUR volume. That remaining value is useful for forecasting, facility debottlenecking, and decline checks, because it ties engineering targets to a tangible volume rather than only a percentage.
Screening incremental recovery opportunities
Incremental recovery represents uplift beyond the base plan, often from EOR, infill, recompletions, or improved sweep. Treat it as an estimate with uncertainty and test low, mid, and high cases. A small incremental volume can be material when OOIP is modest, while a large field may need a bigger absolute uplift to move RF noticeably. Use the precision setting to avoid false certainty when inputs are still preliminary.
Reporting and benchmarking with RF outputs
Use RF outputs to support reporting and benchmarking. Compare current RF to analog fields at similar maturity, then compare ultimate RF to the range achievable with comparable drive and permeability. Track RF over time alongside water cut, pressure maintenance, and well count so the percentage has operational meaning. When exporting CSV or PDF, include the assumptions behind OOIP, Nr, and any incremental recovery so reviewers can audit the scenario.
FAQs
What does OOIP mean in this tool?
OOIP is the original in-place volume estimate for the reservoir or system. Use volumetrics, material balance, or an audited reference. Enter the same conditions and unit basis used for production volumes.
Can the recovery factor exceed 100%?
It should not under consistent definitions. Values above 100% usually indicate unit mismatch, double counting of volumes, or an OOIP estimate that is too low. Review assumptions, conversions, and whether EUR components overlap.
What if I only know cumulative production (Np)?
Enter OOIP and Np, then leave Nr and EOR blank or zero. The calculator will report current recovery factor and set EUR equal to Np. Update Nr and EOR later as a development plan or study matures.
How do I use it for gas projects?
Use OGIP in the OOIP field and keep all inputs in the same gas unit, such as scf or Mscf. Ensure production is at the same standard conditions. The formulas remain identical because RF is a ratio of consistent volumes.
What is the difference between Nr and EOR here?
Nr represents remaining recoverable volume under the base plan and current technology assumptions. EOR is an incremental uplift beyond that base, such as miscible injection or improved sweep. Keep them separate to avoid inflating EUR.
Is this calculator suitable for official reserves booking?
It is best for screening, consistency checks, and reporting support. Official booking typically requires detailed reservoir modeling, approved economic assumptions, and governance review. Use the PDF/CSV exports to document inputs, but validate with your reserves process.
Notes and Limitations
Results depend on the quality of OOIP and recoverable estimates. This tool supports engineering screening and documentation, not a substitute for detailed reservoir studies or audited reserves reporting.