# Dimensionless time for semi-steady state flow in coal bed methane reservoirs

## Input(s)

$k_{g}$: Effective Gas Compressibility (1/psi)

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

$\emptyset$: Porosity (fraction)

$\mu_{g i}$: Gas Viscosity at Initial Pressure $(\mathrm{cP})$

$c_{t i}$: Total Compressibility at Initial Pressure $(1 / \mathrm{psi})$

A: Drainage Area $\left(\mathrm{ft}^{2}\right)$

## Output(s)

$t_{D A}$: Dimensionless Time (dimensionless)

## Formula(s)

$\mathrm{t}_{\mathrm{DA}}=\frac{0.0002637 * \mathrm{k}_{\mathrm{g}} * \mathrm{t}}{\emptyset * \mu_{\mathrm{gi}} * \mathrm{c}_{\mathrm{ti}} * \mathrm{~A}}$## Reference(s)

Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3, Page: 221 .