Well shut-in pressure during buildup (Horner plot)
Input(s)
\(p_{i}\): Initial False Pressure (psi)
\(Q_{o}\): Stabilized Well Flow Rate before Shut-in (STB/day)
\(B_{o}\): Oil Formation Volume Factor (bbl/STB)
\(\mathrm{k}\): Permeability \((\mathrm{mD})\)
\(\mu_{o}\): Oil Viscosity \((\mathrm{cP})\)
\(t_{p}\): Flowing Time before Shut-in (h)
\(\Delta \mathrm{t}\): Shut-in Time (h)
h: Thickness (ft)
Output(s)
\(p_{w s}\): Shut-in Pressure (psi)
Formula(s)
\[
p_{w s}=p_{i}-\left(\frac{162.6 * Q_{o} * \mu_{o} * B_{o}}{k * h}\right) * \log \left(\frac{t_{p}+\Delta t}{\Delta t}\right)
\]
Reference(s)
Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 1, Page: 56.