Dimensionless buildup pressure for steam or gas flow

Input(s)

$k$: Effective Permeability of Flowing Phase (D)

$h$: Net Formation Thickness (m)

$P_{i}$: Initial Reservoir Pressure (psi)

$P_{w s}$: Shut in Pressure (psi)

$M$: Molecular Weight $(\mathrm{g} / \mathrm{g} \mathrm{mol})$

$q$: Production Rate (tons/h $(1000 \mathrm{~kg} / \mathrm{h}))$

Z: Real Gas Law Deviation Factor (Ratio)

$\mu$: Viscosity of Flowing Fluid (cP)

$T$: Absolute Formation Temperature $\left({ }^{\circ} \mathrm{K}\right)$

Output(s)

$P_{D s}$: Dimensionless Pressure (dimensionless)

Formula(s)

$$ P_{D s}=\frac{\operatorname{Mkh}\left(P_{i}^{2}-P_{w s}{ }^{2}\right)}{0.01291 q \mu Z T} $$

Reference(s)

Ramey Jr, H. J. (1981). Reservoir Engineering Assessment of Geothermal Systems. Department of Petroleum Engineering, Stanford University, Page: (5.7).