Real Gas Isothermal Compressibility with Z-Factor Derivative Calculator
Enter the required inputs, confirm the units, and run the calculator to solve c_g. Review the formula source and assumptions before using the result in engineering work.
Calculation context and source notes
Real Gas Isothermal Compressibility with Z-Factor Derivative calculates real gas isothermal compressibility for gas properties workflows in phase behavior and thermodynamics. The page keeps the declared variables, units, source relationship, and output definition visible for technical review.
Use this formula when the listed inputs (P, z, dz_dP) are known and the assumptions behind the cited gas properties relationship match the engineering case being checked.
Solves for
c_g (1/psi)
Best next page
Formula, variables, and sourceFormula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns c_g = 0.000357 1/psi. Defaults demonstrate the implementation; they are not recommended field values.
3000
0.85
-0.00002
Input definitions
P
psiaPressure
z
dimensionlessGas Compressibility Factor
dz_dP
1/psiIsothermal Derivative of Z Factor with Respect to Pressure
Output definitions
c_g
Real Gas Isothermal Compressibility
dz_dP
Isothermal Derivative of Z Factor with Respect to Pressure
Engineering use, assumptions, and limits
Use this formula when the listed inputs (P, z, dz_dP) are known and the assumptions behind the cited gas 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 Real Gas Isothermal Compressibility with Z-Factor Derivative calculator need?
The calculation uses Pressure (P), Gas Compressibility Factor (z), Isothermal Derivative of Z Factor with Respect to Pressure (dz_dP). Enter values on the units shown beside each field.
What result does this calculator return?
The primary result is real gas isothermal compressibility in 1/psi. 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.
Penn State PNG 520. Isothermal Compressibilities, real-gas compressibility, Equation 18.19.
Open source reference