Steam Drive Cumulative Oil Produced - Prats Formula
Steam Drive Cumulative Oil Produced - Prats calculates cumulative oil produced for waterflooding and eor workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (phi, h_n, h_t, S_oi, S_or, E_c, V_s) are known and the assumptions behind the cited waterflooding and eor 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.
Default example
Using the default inputs, N_p equals 502,718.4 bbl.
0.3
40
50
0.7
0.25
0.6
1000
Inputs
phi
fractionPorosity
h_n
ftNet thickness
h_t
ftGross thickness
S_oi
fractionInitial oil saturation
S_or
fractionResidual oil saturation
E_c
fractionCapture efficiency
V_s
acre-ftVolume of steam in reservoir
Outputs
N_p
Cumulative oil produced
phi
Porosity
h_n
Net thickness
h_t
Gross thickness
S_oi
Initial oil saturation
S_or
Residual oil saturation
E_c
Capture efficiency
V_s
Volume of steam in reservoir
Source and review
reviewedThermal Recovery Monograph, Prats, M. (1986)
Prats, M. 1986. Thermal Recovery Monograph Vol. 7. Society of Petroleum Engineers, Houston, Page 75.
Source