Oil in Place for Undersaturated Oil Reservoirs without Fluid Injection Formula
Oil in Place for Undersaturated Oil Reservoirs without Fluid Injection calculates oil in place for material balance and production workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (N_p, B_o, B_oi, S_wi, c_w, c_f, dP) are known and the assumptions behind the cited material balance and production 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 equals 1,827,485.380117 STB.
100000
1.25
1.2
0.25
0.000003
0.000005
2000
Inputs
N_p
STBProduced Oil
B_o
rb/STBOil Formation Volume Factor
B_oi
rb/STBInitial Oil Formation Volume Factor
S_wi
fractionInitial Water Saturation
c_w
1/psiWater Compressibility
c_f
1/psiFormation Compressibility
dP
psiPressure Differential
Outputs
N
Oil in Place
N_p
Produced Oil
B_o
Oil Formation Volume Factor
dP
Pressure Differential
Source and review
reviewedAdvanced Reservoir Engineering, Ahmed, T., McKinney, P. D. (2005)
Ahmed, T. and McKinney, P. D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 5, Page 333.
Source