Cumulative Oil Production – Undersaturated Oil Reservoirs Calculator
Enter the required inputs, confirm the units, and run the calculator to solve Np. Review the formula source and assumptions before using the result in engineering work.
Calculation context and source notes
Cumulative Oil Production – Undersaturated Oil Reservoirs calculates cumulative oil production for pvt and rock-fluid properties workflows in reservoir engineering. The page keeps the declared variables, units, source relationship, and output definition visible for technical review.
Use this formula when the listed inputs (N, c_e, Bo, Boi, dP) are known and the assumptions behind the cited pvt and rock-fluid properties relationship match the engineering case being checked.
Solves for
Np (STB)
Best next page
Formula, variables, and sourceFormula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns Np = 5,454.545455 STB. Defaults demonstrate the implementation; they are not recommended field values.
1000000
5e-6
1.1
1.2
1000
Input definitions
N
STBInitial Oil-in-Place
c_e
1/psiEffective Compressibility
Bo
bbl/STBOil Formation Volume Factor at Assumed Reservoir Pressure
Boi
bbl/STBOil Formation Volume Factor at Initial Reservoir Pressure
dP
psiPressure Differential
Output definitions
Np
Cumulative Oil Production
N
Initial Oil-in-Place (rearranged)
c_e
Effective Compressibility (rearranged)
Bo
Oil FVF at Current Pressure (rearranged)
Boi
Oil FVF at Initial Pressure (rearranged)
dP
Pressure Differential (rearranged)
Engineering use, assumptions, and limits
Use this formula when the listed inputs (N, c_e, Bo, Boi, dP) are known and the assumptions behind the cited pvt and rock-fluid properties relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Frequently asked questions
What inputs does the Cumulative Oil Production – Undersaturated Oil Reservoirs calculator need?
The calculation uses Initial Oil-in-Place (N), Effective Compressibility (c_e), Oil Formation Volume Factor at Assumed Reservoir Pressure (Bo), Oil Formation Volume Factor at Initial Reservoir Pressure (Boi), Pressure Differential (dP). Enter values on the units shown beside each field.
What result does this calculator return?
The primary result is cumulative oil production in STB. The formula section shows the declared relationship, variables, and a reproducible default calculation.
What should I check before using the result?
Confirm the unit basis, source applicability, and input quality. The calculation does not replace a full engineering model or operating procedure. Mixing unit systems without converting the inputs.
Source and record status
Source metadata identifies the relationship implemented by the calculator. Check the cited edition, unit basis, and scope against the engineering case before operational use.
Ahmed, T., McKinney, P.D. (2005). Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 5, Page: 333.
Open source reference