Pseudosteady-State Slope in Pressure Buildup Test Formula
Pseudosteady-State Slope in Pressure Buildup Test calculates pseudosteady-state pressure buildup slope for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (Q, B, c_t, A, h, phi) 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, m_pss equals 1.559733 psi/h.
500
1.2
0.00001
1000000
50
0.18
Inputs
Q
STB/dayFlow Rate
B
bbl/STBFormation Volume Factor
c_t
1/psiTotal Compressibility
A
ft^2Drainage Area
h
ftNet Pay Thickness
phi
fractionPorosity
Outputs
m_pss
Pseudosteady-State Pressure Buildup Slope
Q
Flow Rate
B
Formation Volume Factor
c_t
Total Compressibility
A
Drainage Area
h
Net Pay Thickness
phi
Porosity
Source and review
reviewedAhmed, T. and McKinney, P. D. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 1, Page 33.
Source