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