Water expansion term in gas reservoirs

Input(s)

$B_{g}$: Initial Gas Formation Factor $\left(\mathrm{MSCF} / \mathrm{ft}^{3}\right)$

$c_{w}$: Water Compressibility $(1 / \mathrm{psi})$

$s_{w}$: Initial Water Saturation (fraction)

$c_{f}$: Formation Compressibility $(1 / \mathrm{psi})$

P: Pressure Differential (psi)

Output(s)

$E_{f}$: Expansion Term (fraction)

Formula(s)

$$ E_{f}=\frac{B_{g} *\left(c_{w} * s_{w}-c_{f}\right) * P}{1-s_{w}} $$

Reference(s)

Ahmed, T., McKinney, P.D. Advanced Reservoir Engineering, Gulf Publishing House, Burlington, MA, 2015.