Dimensionless Buildup Pressure from Semilog Slope Formula
Dimensionless Buildup Pressure from Semilog Slope calculates dimensionless buildup pressure for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (P_i, P_ws, m) 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, P_Ds equals 4.597701 dimensionless.
3000
2800
50
Inputs
P_i
psiInitial Reservoir Pressure
P_ws
psiShut-In Pressure
m
psi/log cycleSemilog Buildup Slope
Outputs
P_Ds
Dimensionless Buildup Pressure
P_i
Initial Reservoir Pressure
P_ws
Shut-In Pressure
m
Semilog Buildup Slope
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 5.8.
Source