Choke size for a target rate (Gilbert-type correlations)
The choke size that gives a target liquid rate of a flowing well at a known tubing head pressure and gas-liquid ratio (critical flow).
S = (A · R^B · q / P_wh)^(1/C)Gilbert: A = 10.0, B = 0.546, C = 1.89The correlations hold for critical (sonic) flow: the upstream pressure is at least 1.7 times the flowline pressure (Gilbert). In subcritical flow the rate also depends on the line pressure and the formula overstates it. The pressure is gauge, the gas-liquid ratio is per barrel of oil and water, the choke size is in 64ths of an inch (the units can be switched to metric). The correlations are empirical: tune A to your field's tests.
Source: Gilbert W.E., Flowing and Gas-Lift Well Performance, API Drilling and Production Practice, 1954; the Ros, Baxendell and Achong coefficients — Guo B., Lyons W.C., Ghalambor A., Petroleum Production Engineering, ch. 5
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
Gauge pressure; in metric units choose MPa(g).
Gas per unit volume of oil and water together; it may be entered in m³/m³ and is converted.
Unit converter for this formulaLiquid rate · Pressure · Gas-oil ratio · Length
- m³/d1
- m³/h0.0416667
- L/s0.0115741
- L/min0.694444
- m³/min0.000694444
- bbl/d6.28981
- Mbbl/d0.00628981
- ft³/d35.3147
- US gpm0.183453
- bbl/min0.00436792
A day is 24 hours.
More in Gas and chokes
Gas volume at 20 °C and 101.325 kPa (GOST 2939) from the volume at operating pressure and temperature, with the deviation factor; the gas formation volume factor. The same works for a flow rate: actual m³/h give standard m³/h.
Liquid rate of a flowing well at critical two-phase flow through the choke, from the tubing head pressure, the gas-liquid ratio and the choke size: the Gilbert, Ros, Baxendell and Achong correlations.
The critical gas velocity that lifts water or condensate droplets out of the well, and the matching minimum gas rate for a given tubing size — after Turner (with the +20 % adjustment) or Coleman (without it). Below this rate liquid accumulates at the bottom and loads the well up.
Results are engineering estimates from standard formulas; for design decisions check them against the codes, project documents and specialists' calculations. The formulas carried over from the original set are unchanged, and their errors are described in the notes.