Reservoir EngineeringMaterial Balance
Gas Recovery Factor from p/z Material Balance Formula
Gas Recovery Factor from p/z Material Balance calculates gas recovery factor for material balance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (P_z, P_i_z_i) are known and the assumptions behind the cited material balance 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, RF_g equals 0.25 fraction.
P_zpsi
3000
P_i_z_ipsi
4000
Inputs
P_z
psiCurrent Pressure to Gas Compressibility Factor Ratio
P_i_z_i
psiInitial Pressure to Gas Compressibility Factor Ratio
Outputs
RF_g
fraction
Gas Recovery Factor
P_z
psi
Current Pressure to Gas Compressibility Factor Ratio
P_i_z_i
psi
Initial Pressure to Gas Compressibility Factor Ratio
Source and review
reviewedPetroleum Office. Material Balance Overview, p/z method for volumetric gas reservoirs.
Source