Reservoir EngineeringRock Properties
Quadratic Porosity Multiplier from Rock Compressibility Formula
Quadratic Porosity Multiplier from Rock Compressibility calculates porosity at current pressure for rock properties workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (phi_ref, c_rock, P, P_ref) are known and the assumptions behind the cited rock 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, phi equals 0.17964 fraction.
phi_reffraction
0.18
c_rock1/psi
0.000004
Ppsi
3500
P_refpsi
4000
Inputs
phi_ref
fractionReference Porosity
c_rock
1/psiRock Compressibility
P
psiCurrent Pressure
P_ref
psiReference Pressure
Outputs
phi
fraction
Porosity at Current Pressure
X_qrc
dimensionless
Quadratic Rock Compressibility Exponent
phi_ref
fraction
Reference Porosity
c_rock
1/psi
Rock Compressibility
P
psi
Current Pressure
P_ref
psi
Reference Pressure
Source and review
reviewedOpenGoSim Cirrus documentation. Rock Compressibility Model theory page.
Source