Choke Flow Calculator
Calculate wellhead pressure, flow rate, or choke size using Gilbert (1954) and Ros correlations for multiphase flow through chokes.
Calculate Wellhead Pressure from Rate, GLR & Choke
Gilbert: Pwh = 435 × q × R0.546 / D1.89
Ros: Pwh = 523.16 × q × R0.546 / D1.89
Where R = GLR (scf/bbl), D = choke size (64ths of an inch), q = liquid rate (bbl/d)
Results
Gilbert Result
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Ros Result
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Choke Size (inches)
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Choke Area (in²)
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Gilbert Pwh for Common Choke Sizes
How this was calculated
Gilbert (1954): Pwh = 435 * q * R^0.546 / D^1.89. Empirical correlation for critical (sonic) flow through oilfield chokes. Valid when upstream pressure is roughly 2x or more of downstream pressure.
Ros (1960): Uses same form with coefficient 523.16 instead of 435. Generally gives higher pressures than Gilbert.
Units: Pwh in psi, q in bbl/d, R (GLR) in scf/bbl, D in 64ths of an inch.
Assumptions: Critical (sonic) flow through the choke. Multiphase (oil + gas) flow. Atmospheric downstream pressure. No water correction.
Limitations: These are empirical correlations developed for specific field conditions. Accuracy varies with fluid properties and operating conditions. For subcritical flow, use more rigorous models.
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Book a free strategy call →Understanding Choke Flow in Production Engineering
Production chokes are flow-restricting devices installed at the wellhead to control flow rates, protect downstream equipment, and maintain back-pressure on the reservoir. Proper choke sizing is critical for optimizing production while preventing sand production, coning, and equipment damage.
The Gilbert equation (1954) is the most widely used empirical correlation for predicting multiphase flow through chokes under critical (sonic) flow conditions. Critical flow occurs when the upstream pressure is approximately twice the downstream pressure, meaning the flow rate is independent of downstream conditions. The equation relates wellhead pressure to liquid rate, gas-liquid ratio, and choke size.
The Ros correlation uses the same functional form but with a different coefficient (523.16 vs. 435), generally predicting higher pressures. In practice, engineers often compare both correlations and use field-calibrated coefficients for their specific operating conditions.
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