Total Compressibility from Phase Saturations Formula
Total Compressibility from Phase Saturations calculates total compressibility for pvt and rock-fluid properties workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (c_g, c_o, c_w, c_f, S_g, S_o, S_w) 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.
Default example
Using the default inputs, c_t equals 0.000064 1/psi.
0.0005
0.000012
0.000003
0.000005
0.1
0.65
0.25
Inputs
c_g
1/psiGas Compressibility
c_o
1/psiOil Compressibility
c_w
1/psiWater Compressibility
c_f
1/psiFormation Compressibility
S_g
fractionGas Saturation
S_o
fractionOil Saturation
S_w
fractionWater Saturation
Outputs
c_t
Total Compressibility
c_g
Gas Compressibility
c_o
Oil Compressibility
c_w
Water Compressibility
c_f
Formation Compressibility
Source and review
reviewedPetroWiki total compressibility definition and Petroleum Engineers formula entry.
Source