# Dimensionless buildup time

## Input(s)

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

\(t\): Time (h)

\(\varnothing\): Porosity (Per cent)

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

\(c_{t}\): Total System Effective Isothermal Compressibility \(\left(\mathrm{kg} / \mathrm{cm}^{2}\right)^{-1}\)

\(r_{w}\): Well Radius (m)

## Output(s)

\(t_{D}\): Dimensionless time (dimensionless)

## Formula(s)

\[
t_{D}=\frac{0.3604 k t}{\varnothing \mu c_{t} r_{w}^{2}}
\]

## Reference(s)

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