Gas Reservoir p/z Material Balance & OGIP Calculator

Determine Original Gas In Place ($G$ / OGIP), gas compressibility factor ($Z$), ultimate recovery factor, and remaining reserves at abandonment pressure.

Gas Reservoir Pressures & Production

Initial Pressure p_i (psi):

Current Pressure p (psi):

Reservoir Temp T (°F):

Gas Specific Gravity γ_g (Air=1):

Cumulative Production G_p (Bcf):

Abandonment Pressure p_ab (psi):

OGIP & Recoverable Reserves

Original Gas in Place (G / OGIP)

Total Recoverable Reserves (EUR)

Initial (p/Z)_i

Current (p/Z)

Remaining Reserves

Volumetric Depletion Linearity

p/Z = (pi / Zi) · (1 - Gp / G) | Straight-line decline confirms closed volumetric tank.

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Gas Reservoir p/z Material Balance & OGIP Calculator

Gas Reservoir Pressures & Production

OGIP & Recoverable Reserves

Frequently Asked Questions