# Dimensionless pressure (linear flow/constant rate production/general case)

## Input(s)

\(p_{i}\): Initial Reservoir Pressure \((\mathrm{psi})\)

B: Volume Factor \((\mathrm{RB} / \mathrm{STB})\)

\(\mu\): Oil Viscosity \((\mathrm{cP})\)

\(\mathrm{k}\): Permeability \((\mathrm{mD})\)

A: Cross Section Area (ft)

q: Flow Rate (STB/day)

p: Pressure \((\mathrm{psi})\)

## Output(s)

\(p_{D}\): Dimensionless Pressure (dimensionless)

## Formula(s)

\[
p_{D}=\frac{k * A^{0.5}}{141.2 * q * B * \mu} *\left(p_{i}-p\right)
\]

## Reference(s)

Lee, J., Rollins, J. B., & Spivey, J. P. (2003). Pressure Transient Testing (Vol. 9). Richardson, Texas: Society of Petroleum Engineers, Page: 9.