Drawdown Semilog Slope for Bottomhole Flowing Pressure Formula
Drawdown Semilog Slope for Bottomhole Flowing Pressure calculates drawdown semilog slope for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (Q_o, mu_o, B_o, k, h) 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 equals 24.39 psi/cycle.
500
1.2
1.25
100
50
Inputs
Q_o
STB/dayOil Flow Rate
mu_o
cPOil Viscosity
B_o
bbl/STBOil Formation Volume Factor
k
mDPermeability
h
ftFormation Thickness
Outputs
m
Drawdown Semilog Slope
Q_o
Oil Flow Rate
mu_o
Oil Viscosity
B_o
Oil Formation Volume Factor
k
Permeability
h
Formation Thickness
Source and review
reviewedAdvanced Reservoir Engineering, Ahmed, T., McKinney, P. D. (2005)
Ahmed, T. and McKinney, P. D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 1, Page 45.
Source