FLUIDS
When a full composition is more than the job needs, start from oil gravity, gas gravity and GOR. Published correlations give oil, gas and water properties against pressure, checked against your lab points and ready for every module and your simulator.
WHAT IT DOES
Black-oil PVT treats the reservoir fluid as stock-tank oil, surface gas and water, with gas dissolving in the oil as pressure rises. Enter the oil API gravity, the gas specific gravity, the producing GOR, the reservoir temperature and any CO₂, H₂S and N₂, and Converge computes the bubble point, solution GOR, formation volume factors, densities, compressibilities and viscosities across the pressure range.
Five sets of published oil correlations are available. Paste measured points from a lab report and Converge ranks the sets by how well each reproduces them, then lets you tune the chosen set: an Rs shape exponent, and a multiplier and shift for the formation volume factor and for viscosity. Differential-liberation data are converted to a separator basis before they are compared.
For simulator work, the tables come from the tuned equation-of-state fluid: the equilibrium oil is flashed through your separator train rather than the reservoir flash, which is how the volumes a simulator reports match what the separators will measure.
KEY CAPABILITIES
Bubble point, solution GOR and oil formation volume factor come from one of five published correlation sets, chosen by you or by fit to your lab points.
Dead-oil, saturated and undersaturated viscosity are computed separately, as the published methods intend.
Gas properties use pseudo-critical correlations with a correction for sour and inert components, and water properties follow McCain.
Correlations are a starting point. When you have measurements, Converge measures the gap and closes it.
Black-oil tables for simulators come from the tuned equation-of-state fluid, flashed through the separator train you define.
Every deck is written in field or metric units, ready to include in a simulator data file.
WORKFLOW
Enter API gravity, gas gravity, GOR, reservoir temperature and any CO₂, H₂S and N₂.
Choose a correlation set, or paste lab rows and let Converge rank the five sets by fit.
Fit the Rs exponent and the Bo and viscosity adjustments to the measured points, if you have them.
Make the fluid the project fluid, so every module reads the same properties.
Download CSV tables, or simulator decks from the equation-of-state workspace.
VALIDATION
Each correlation set is checked against a hand calculation from the published equations, and the Z-factor against the published method at four pressures. Values are in oilfield units, as the references give them.
| Check | Reference | Converge | Tolerance |
|---|---|---|---|
| Standing bubble point, 35 °API, gas gravity 0.75, 650 scf/STB, 200 °F (V1) | 2,748 psia | 2,747.8 psia | ±1.6 psi |
| Standing oil formation volume factor at the bubble point (V3) | 1.375 rb/STB | 1.3749 rb/STB | 0.0005 rb/STB |
| Beggs-Robinson live-oil viscosity at the bubble point (V4) | 0.4927 cp | 0.4924 cp | 0.1% |
| Z-factor, Dranchuk-Abou-Kassem with Sutton, gas gravity 0.7, 200 °F, at 1,000 to 10,000 psia (V6) | Published method | 0.01–0.03% | 0.05% |
| McCain water-viscosity pressure correction at 5,000 psia (V7) | +28% | +28% | ±0.5 point |
| Gas formation volume factor at 3,000 psia (V9) | 0.000983 rb/scf | 0.000983 rb/scf | 10⁻⁶ rb/scf |
The other four oil sets each match their hand calculation, and every bubble point inverts back to the input GOR.
INPUTS AND OUTPUTS
CONNECTED MODULES
Set it as the project fluid and the modules that work in black-oil terms read it directly.
FAQ
Standing, Vasquez-Beggs, Glasø, Petrosky-Farshad and Al-Marhoun for the oil; Beggs-Robinson, Vasquez-Beggs and Beal for viscosity; Dranchuk-Abou-Kassem with Sutton pseudo-criticals and the Wichert-Aziz correction for gas; McCain for water.
Paste your lab points and auto-pick ranks the five oil sets by how well each reproduces them. You can accept the best fit or choose another, then tune it.
A table in which each pressure's equilibrium oil is flashed through your separator train, rather than straight to stock-tank conditions in one step. Formation volume factors and GOR then match what the separators will measure.
Yes. PVTO, PVDG, PVTW and DENSITY, or PVTG and PVTO for condensates, plus RSVD and RVVD and a *PVT keyword-format table, all in field or metric units. The decks come from the equation-of-state workspace; correlation mode exports CSV.
Yes. The Wichert-Aziz correction adjusts the pseudo-critical properties for CO₂ and H₂S, and N₂ is included in the mixing.