Dimensionless Storage Constant for Gas Buildup Tests Formula
Dimensionless Storage Constant for Gas Buildup Tests calculates dimensionless storage constant for gas for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (C_prime, Z, T, M, phi, h, c_t, r_w) are known and the assumptions behind the cited pressure transient analysis 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_D equals 4,320 dimensionless.
0.00002
0.9
600
18
0.2
30
0.00001
0.25
Inputs
C_prime
tons/(kg/cm^2)^2Gas Wellbore Storage Constant
Z
dimensionlessGas Deviation Factor
T
KAbsolute Formation Temperature
M
g/gmolGas Molecular Weight
phi
fractionPorosity
h
mNet Formation Thickness
c_t
(kg/cm^2)^-1Total System Effective Compressibility
r_w
mWell Radius
Outputs
C_D
Dimensionless Storage Constant for Gas
C_prime
Gas Wellbore Storage Constant
Z
Gas Deviation Factor
T
Absolute Formation Temperature
M
Gas Molecular Weight
phi
Porosity
h
Net Formation Thickness
c_t
Total System Effective Compressibility
r_w
Well Radius
Source and review
reviewedReservoir Engineering Assessment of Geothermal Systems, Ramey Jr., H.J. (1981)
Ramey Jr., H.J. 1981. Reservoir Engineering Assessment of Geothermal Systems, Stanford University, Page 5.18.
Source