Gas material balance equation

Input(s)

\(\frac{\mathrm{P}_{\mathrm{i}}}{\mathrm{z}_{\mathrm{i}}}\): Ratio of Pressure to Compressibility Factor at Initial Conditions (psi)

\(\mathrm{P}_{\mathrm{SC}}\): Pressure at Standard Conditions (psi)

\(\mathrm{T}_{\mathrm{SC}}\): Temperature at Standard Conditions \(\left({ }^{\circ} \mathrm{R}\right)\)

T: Current Temperature \(\left({ }^{\circ} \mathrm{R}\right)\)

V: Original Gas Volume \(\left(\mathrm{ft}^{3}\right)\)

\(\mathrm{G}_{\mathrm{p}}\): Cumulative Gas Production \((\mathrm{SCF})\)

Output(s)

\(\frac{\mathrm{P}}{\mathrm{z}}\): Ratio of Pressure to Compressibility Factor at Current Conditions for \(\mathrm{P} / \mathrm{z}\) vs \(\mathrm{G}_{\mathrm{p}}\) plot (psi)

Formula(s)

Reference(s)

Ahmed, T., McKinney, P.D.2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter: 3, Page: 203.