Gas Viscosity Calculator
Natural gas viscosity, density, and Z-factor with N2, CO2, and H2S corrections — defensible PVT for reservoir simulation, well testing, and gas-well economics.
The problem
Reservoir engineers and well-test interpreters need defensible gas viscosity and Z-factor for PVT decks, simulation runs, and rate-transient analysis — especially in sour gas where impurities crater the value. Textbook calculators ignore N2/CO2/H2S corrections, and getting Z-factor wrong by 3% on a 100 Bcf field can swing your in-place estimate by $50M+. When a reserve auditor or simulation reviewer asks "which correlation did you use?", you need a citable answer, not a screenshot of a spreadsheet.
What you get
- →Gas viscosity (cp), density, and Z-factor at reservoir T and P — ready for an Eclipse or CMG PVT deck.
- →N2, CO2, and H2S impurity adjustments built in — no manual Wichert-Aziz steps.
- →Pseudocritical Tpr / Ppr output so a reviewer can spot-check the inputs to the Z-factor solve.
- →Downloadable XLSX with cited correlation and a row for each P/T point — drops into a PVT report appendix.
- →Multi-well / multi-condition batch mode for screening a basin of gas wells.
Asset Forecasting & Evaluation Suite
Run the live Gas Viscosity Calculator on your data
This calculator is part of Petropt's Asset Forecasting & Evaluation Suite. Request access to run it on your actual temperature, pressure, gas gravity, and impurity inputs and download an engineering-grade workbook.
What the live tool produces
- gas viscosity (cp) via Lee-Gonzalez-Eakin
- gas density + Z-factor (Hall-Yarborough or DAK)
- Tpr / Ppr corrections
- N2 / CO2 / H2S impurity adjustments (Carr-Kobayashi-Burrows)
- downloadable workbook
Who uses this
- →Reservoir engineers building PVT decks for simulation runs and material-balance models.
- →Well-test interpreters validating Z-factor for pressure-transient and rate-transient analysis.
- →A&D engineers screening sour-gas asset acquisitions where impurity correction drives the number.
Pair with
Standing-Katz Z-Factor
Z-factor chart + math
Cross-check Z-factor against the classic chart.
Water Properties
McCain brine math
Pair gas PVT with formation-water properties.
Orifice Flow
Custody-transfer math
Use gas density downstream for allocation.
Asset Forecasting
DCA + economics
Roll PVT into a decision-ready asset memo.