Gas saturation - Water-drive gas reservoirs
Input(s)
\(G\): Gas Initially in Place (SCF)
\(G_{p}\): Cumulative Gas Production (SCF)
\(B_{g}\): Volume Factor \((\mathrm{bbl} / \mathrm{SCF})\)
\(B_{g i}\): Initial Gas Formation Factor (bbl/SCF)
\(W_{e}\): Cumulative Water Influx \((\mathrm{bbl})\)
\(W_{p}\): Cumulative Water Production (STB)
\(B_{w}\): Water Formation Volume Factor (rb/STB)
\(S_{w i}\): Initial Water Saturation (fraction)
\(S_{\text {grw }}\): Residual Gas Saturation to Water Displacement (fraction)
Output(s)
\(\mathrm{S}_{\mathrm{g}}\): Gas Saturation (fraction)
Formula(s)
\[
\mathrm{S}_{\mathrm{g}}=\frac{\left(G-G_{p}\right) * B_{g}-\frac{W_{e}-W_{p} * B_{w}}{1-S_{w i}-S_{g r w}} * S_{g r w}}{\left(\frac{G * B_{g i}}{1-S_{w i}}\right)-\left(\frac{W_{e}-W_{p} * B_{w}}{1-S_{w i}-S_{g r w}}\right)}
\]
Reference(s)
Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3, Page: 208.