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Choke Size Flow Calculator

Work out choke size flow instantly with clear inputs, formula shown and shareable results.

About Choke Size Flow Calculator

Under critical (sonic) flow, rate through a choke depends on upstream pressure and bean size only, not on downstream pressure. Gilbert-type correlations give q proportional to upstream pressure x bean size to the power 1.89 divided by GOR to the power 0.546. Critical flow holds while downstream pressure is below about 55% of upstream.

Formulas

Gilbert choke correlation

q = C x p_upstream x S^1.89 / (435 x GOR^0.546)

Critical flow limit

Critical flow while p_downstream / p_upstream < approximately 0.55

Worked example

With the default values below, Choke Size Flow Calculator returns Oil Flow Rate of 880.33. Change any input above and every figure here is recalculated in your browser.

Inputs used

Choke Bean Sizeminimum 0.01 64ths of an inch
32 64ths of an inch
Upstream Pressureminimum 0.01 psi
1,800 psi
Gas-Oil Ratiominimum 0.01 scf/bbl
600 scf/bbl
Discharge Coefficientminimum 0.01
10

Results

Oil Flow Rate
880.33
Choke Diameter
0.50000
Choke Flow Area
0.196350
Critical Downstream Pressure
990.0

Step by step

  1. 1Values used
  2. 2Gilbert choke correlation
  3. 3Critical flow limit
  4. 4Oil Flow Rate= 880.33
  5. 5Choke Diameter= 0.50000
  6. 6Choke Flow Area= 0.196350
  7. 7Critical Downstream Pressure= 990.0

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is critical flow desirable?

It isolates the well from downstream pressure fluctuations, so production is stable and metering is predictable. Losing critical flow makes rate sensitive to separator and pipeline pressure.

How accurate are choke correlations?

Within 10-20% at best, and they are sensitive to the coefficient chosen. They are used for surveillance and allocation, not for reserves or design decisions without calibration against tested rates.

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