Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

Pressure (Pa)

Absolute gas pressure.

Temperature (K)

Absolute gas temperature.

Gas gravity

Specific gravity of the hydrocarbon gas (air = 1).

Compute the natural-gas compressibility factor with Sutton pseudo-critical properties and the Dranchuk-Abou-Kassem method. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Z factor

Compressibility factor Z at the given conditions.

• Petroleum correlations are fluid-, pressure-, temperature-, and region-dependent. PVT sampling, phase behavior, relative permeability, capillary pressure, heterogeneity, aquifer support, well constraints, history match, and units affect forecasts and reserves.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• Gas Density Calculator

  Compute natural-gas density from the real-gas law using gas gravity and a compressibility factor.

• Gas Formation Volume Factor Calculator

  Compute the gas formation volume factor Bg relating reservoir cubic metres to standard cubic metres at 101.325 kPa and 288.15 K.

• Material Balance Gas Initially In Place Calculator

  Estimate the volumetric gas initially in place from pore volume and the real-gas formation volume factor Bg at standard conditions of 101325 Pa and 288.15 K.