Natural Gas Viscosity with Carr, Kobayashi, and Burrows Correlation

This Excel spreadsheet uses the Carr, Kobayashi, and Burrows correlation to calculate the viscosity of natural gas. The correlation is valid for sweet and sour gas.

The Carr, Kobayashi, and Burrows correlation was published in 1954. It is valid between temperatures of 32 F to 400 F, reduced pressures below 20, and CO₂, N₂ and H₂S concentrations below 15%.

The correlation was originally presented in graphs. However, this spreadsheet contains polynomial curve fits to the original graphs given by Dempsey (1965).

This spreadsheet also corrects calculates the viscosity (Standing & Katz, 1977) and pseudo-critical temperature/pressure of natural gas, but corrects for the presence of CO₂, N₂ and H₂S.

A spreadsheet to calculate the viscosity of natural gas based on the Lee, Gonzalez and Eakin correlation is also available; this method, however, is only valid for sweet natural gas.

Download Excel Spreadsheet to Calculate Natural Gas Viscosity using Carr, Kobayashi and Burrows

Calculate Viscosity of Natural Gas with Excel

This Excel spreadsheet will calculate the viscosity of natural gas. The spreadsheet uses the Lee, Gonzalez and Eakin correlation for the viscosity, and the CNGA (California Natural Gas Association) correlation for the compressibility factor.

The Lee, Gonzalez and Eakin correlation, only requires the pressure, temperature and molecular weight of the natural gas, and is relatively accurate compared to more complex methods of predicting viscosity.  It still widely used and accepted.

The CNGA compressibility factor correlation is suitable for pressures above 100 psig (below 100 psig, the compressibility factor is 1)

The Lee, Gonzalez and Eakin correlation was published in 1964 and accurately predicts the viscosity of natural gases with low non-hydrocarbon content, and for temperature between 100 F - 340 F, and pressures between 14.7-8000 psia. Additionally, the correlation is only suitable for sweet gases, and does not accurately describe sour gases (as described in this paper). The correlation has standard deviation of 2.7%, with a maximum deviation of 8.99%. The correlation is

Gas density is predicted by this correlation.

where ρ is the density in g/cm³, P is the pressure in psig, MW is the molecular weight (lb/lbmol), R is the gas constant (10.731 ft³ psi °R⁻¹ lb-mol⁻¹), T is the absolute temperature (°R) and Z is the compressibility factor.

Download Excel Spreadsheet to Calculate the Viscosity of Natural Gas