# Radius of investigation

## Input(s)

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

\(\mathrm{t}\): Time (h)

\(\emptyset\): Porosity (fraction)

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

\(c_{t}\): Total Compressibility \((1 / \mathrm{psi})\)

## Output(s)

\(r_{i}\): Radius of Investigation at the end of Injection Time (ft)

## Formula(s)

\[
r_{i}=0.0359 *\left(\left(\frac{k * t}{\phi * \mu * c_{t}}\right)^{0.5}\right)
\]

## Reference(s)

Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 1, Page: 134