Horner Semilog Buildup Pressure Extrapolation Formula
Horner Semilog Buildup Pressure Extrapolation calculates shut-in bottomhole pressure on horner straight line for pressure transient analysis workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (p_star, m, 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, p_ws equals 3,420 psi.
3500
80
10
Inputs
p_star
psiHorner Extrapolated Pressure at H = 1
m
psi/cyclePositive Semilog Straight-Line Slope Magnitude
H
dimensionlessHorner Time Ratio
Outputs
p_ws
Shut-In Bottomhole Pressure on Horner Straight Line
p_star
Horner Extrapolated Pressure at H = 1
m
Positive Semilog Straight-Line Slope Magnitude
H
Horner Time Ratio
Source and review
reviewedAAPG Wiki, Pressure transient testing, Horner buildup plot and extrapolation discussion.
Source