Initial gas in place for water-drive gas reservoirs

Input(s)

$\mathrm{G}_{\mathrm{p}}$: Cumulative Gas Production at Depletion Pressure (SCF)

$\mathrm{B}_{\mathrm{g}}$: Gas Formation Volume Factor at Depletion Pressure (bbl/SCF)

$\mathrm{W}_{\mathrm{e}}$: Cumulative Water Influx (bbl)

$\mathrm{W}_{\mathrm{p}}$: Cumulative Water Production at Depletion Pressure (STB)

$\mathrm{B}_{\mathrm{w}}$: Water Formation Volume Factor (bbl/STB)

$\mathrm{B}_{\mathrm{gi}}$: Initial Gas Formation Volume Factor (bbl/SCF)

Output(s)

G: Gas Initially in Place (MSCF)

Formula(s)

$$ \mathrm{G}=\frac{\mathrm{G}_{\mathrm{p}} * \mathrm{~B}_{\mathrm{g}}-\left(\mathrm{W}_{\mathrm{e}}-\mathrm{W}_{\mathrm{p}} * \mathrm{~B}_{\mathrm{w}}\right)}{\mathrm{B}_{\mathrm{g}}-\mathrm{B}_{\mathrm{gi}}} $$

Reference(s)

Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3, Page: 207.