Water Two-Phase Formation Volume Factor Formula
Water Two-Phase Formation Volume Factor calculates water two-phase formation volume factor for pvt properties workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (B_w, B_g, R_s, R_i) are known and the assumptions behind the cited pvt 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.
Default example
Using the default inputs, B_tw equals 1.52 rb/STB.
1.02
0.005
600
500
Inputs
B_w
rb/STBSingle-Phase Water Formation Volume Factor
B_g
rb/SCFGas Formation Volume Factor
R_s
SCF/STBCurrent Gas-Water Ratio
R_i
SCF/STBInitial Gas-Water Ratio
Outputs
B_tw
Water Two-Phase Formation Volume Factor
B_w
Single-Phase Water Formation Volume Factor
B_g
Gas Formation Volume Factor
R_s
Current Gas-Water Ratio
R_i
Initial Gas-Water Ratio
Source and review
reviewedCraft, B.C., Hawkins, M. and Terry, R.E. Applied Petroleum Reservoir Engineering, 2nd Edition.
Source