Oil saturation at any depletion state below the bubble point pressure

Input(s)

$\mathrm{S}_{\mathrm{wi}}$: Initial Water Saturation (fraction)

$\mathrm{N}_{\mathrm{p}}$: Cumulative Oil Production (STB)

$\mathrm{N}$: Oil in Place (STB)

$\mathrm{B}_{\mathrm{oi}}$: Initial Oil Formation Volume Factor (bbl/STB)

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

Output(s)

$\mathrm{S}_{\mathrm{o}}$: Oil Saturation (fraction)

Formula(s)

$$ \mathrm{S}_{\mathrm{o}}=\left(1-\mathrm{S}_{\mathrm{wi}}\right) *\left(1-\frac{\mathrm{N}_{\mathrm{p}}}{\mathrm{N}}\right) *\left(\frac{\mathrm{B}_{\mathrm{o}}}{\mathrm{B}_{\mathrm{oi}}}\right) $$

Reference(s)

Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 4, Page: 312.