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Engineering calculator for multiphase oil + water + gas flow.
For a single-phase (liquid) meter, physics is relatively simple: one fluid with known density ρ flows in the pipe; the pressure-drop ↔ flow relation is one equation (often Q ∝ √(ΔP/ρ)), and metrology is a single curve or even one number. For multiphase flow (oil + water + gas) this breaks down for several reasons.
A multiphase meter must work where gas and liquid coexist with different densities, viscosities, and velocities. Pressure drop depends on mixture composition — GVF, phase densities, and flow regime. You cannot take a “10–100 m³/day” water range and apply it to a mixture: at the same ΔP, flow differs at GVF = 5% vs 95%.
Gas and liquid move at different speeds (slip). The same pressure drop maps to different Qgas and Qliq combinations. Classic Venturi with one “mixture” density and no phase distribution model fails — a drift-flux Zuber–Findlay model is used instead.
Flow type (bubbly, slug, annular, dispersed, etc.) depends on GVF, phase velocities, diameter, viscosity, and surface tension. For multiphase meters, regime is part of the metrology model. The GVF section here determines flow structure — meaningless for pure liquid.
Gas rate may be given at standard, normal, or operating conditions; liquid includes WLR; gas may come via GOR. All quantities are reconciled in one model with P, T, densities, and compressibility Z (Peng–Robinson from gas composition).
For multiphase Venturi: direct (ΔP → rates) and inverse (rates → ΔP) problems are solved by bisection with convergence checks — not a tabulated K-factor from a meter datasheet.
Multiphase meters must verify that the instrument covers the specified liquid and gas ranges simultaneously. This site implements that as coverage checking in Venturi sizing.
In short: multiphase metering needs mixture models, GVF, flow regime, and iterative solvers.
Calculators are grouped in the menu: Basic, Venturi, Pro. Access depends on sign-in and access level.
Fundamental gas volume fraction in oil + water + gas flow at operating conditions. With pipe diameter — flow regime from phase velocities. For engineers who need quick gas saturation and regime estimates.
H₂S partial pressure calculation and ISO 15156 material screening. Two modes: simplified (pH₂S only) and engineering — with pH, temperature, chlorides input and an alloy-group recommendation table (carbon steels, martensitic, duplex, nickel alloys).
Convert gas volumetric flow to a unified condition set. Input in std., normal, or operating conditions with P and T; output in all three systems.
Gas density at standard (20 °C) and specified operating conditions from molar composition. Molar mass from the components; operating density uses Peng–Robinson (compressibility Z).
Fast bidirectional conversion between cubic metres and oil barrels. Useful when reports and equipment mix SI and field units.
Bidirectional Celsius ↔ Fahrenheit conversion in real time. Handy when comparing inputs from international specs and datasheets.
Convert between absolute and gauge pressure. Input in Pa, kPa, MPa, bar, atm, kgf/cm², psi, mm Hg, mm H₂O; output in all units both ways.
Bidirectional pressure unit conversion: editing any field instantly updates the others.
Venturi tube calculator — flow calculation for a Venturi meter as a multiphase instrument. Liquid and gas rates (range or point), PVT, geometry, ΔP and velocity limits. Results table, coverage check, Flow Map, inverse calc, PDF export with QR code.
Direct MPFM problem: from measured ΔP determine oil, water, and gas rates (drift-flux model, Peng–Robinson gas composition, well profiles, saved calculations in account).
Inverse problem: given oil, water, and gas rates, find throat ΔP. Same physics as the flow calculator.
Simultaneous calculation for seven Venturi sizes (DN48, DN77, DN94), summary table, flow map with all size contours, and range summation mode.
GVF (Gas Volume Fraction) is the volumetric gas fraction in oil + water + gas flow at operating (reservoir) conditions.
Enter liquid and gas flow rates — the calculator computes GVF and converts gas flow to standard, normal, and operating conditions.
| Parameter | Value | Units | Note |
|---|
When a gas phase is present, H₂S partial pressure is calculated as pH₂S = yH₂S × Pabs. The output below is a preliminary material-group recommendation; final selection still requires full ISO 15156 verification for environment, hardness, welding and temperature limits.
| Parameter | Value | Units | Note |
|---|
| Alloy group | Applicability rating | Comment |
|---|
Convert gas volumetric flow to standard, normal, or operating conditions.
If gas density at standard conditions is entered, conversion uses that value (ideal gas, Z = 1). If the field is empty, density is calculated from the molar composition (Peng–Robinson).
Molar gas composition (default values shown — edit as needed). Used to calculate density when the “gas density at std. conditions” field is empty. The sum should be ≈ 100% (normalised automatically).
Sum: 0 % (should be ≈ 100%)
| Conditions | Flow rate | Units | Note |
|---|
Calculate gas density at standard (20 °C, 0.101325 MPa) and specified operating conditions from molar composition. Molar mass is taken from the components; operating density uses the Peng–Robinson equation (compressibility Z).
Component mole fractions, %. The sum should be ≈ 100% (composition is normalised automatically).
Sum: 0 % (should be ≈ 100%)
| Parameter | Value | Units | Note |
|---|
Bidirectional conversion between cubic metres and oil barrels. Standard: 1 bbl = 0.158987294928 m³.
Instant bidirectional conversion between Celsius and Fahrenheit.
Converts between absolute and gauge (manometric) pressure.
| Unit | Absolute pressure | Gauge pressure |
|---|
Negative gauge values (below atmospheric) are highlighted in red.
Instant bidirectional conversion between common pressure units.
Sizing range for a Venturi tube as a multiphase flow meter (oil + water + gas).
Enter gas flow in either standard conditions, or operating conditions, or via gas-oil ratio. Standard and operating rates cannot be filled at the same time.
| Parameter | Minimum | Maximum | Units |
|---|
The Venturi tube calculator on GVF Calc sizes a multiphase meter (oil + water + gas) from throat geometry, PVT data, and limits on pressure drop and velocities. This is an engineering Venturi calculation, not a single-phase K-factor lookup.
For a Venturi flow calculation, enter liquid rates (min/max or a point), gas rate at standard or operating conditions or via GOR, water cut WLR, pressure, temperature and phase densities. The calculator checks whether the selected Venturi covers liquid and gas ranges together and plots a Flow Map.
In multiphase flow the ΔP–Q relation depends on GVF, phase slip and flow regime. The Venturi calculation here uses a drift-flux model: the direct problem (rates from ΔP) and the inverse problem (ΔP from rates) are consistent with range sizing.
Results can be exported to PDF with a QR code so the Venturi inputs can be reproduced. To compare several sizes, use the Pro section (Flow Map for seven geometries).
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