Annular velocity
Average mud velocity in the annulus between the hole (or casing) and the pipe at a given pump rate.
v_a = Q / (π/4 · (D² − d²))Average velocity without slip: cuttings rise slower by their settling velocity. The velocity needed for hole cleaning comes from the hydraulics program and depends on mud rheology, cuttings size and inclination.
Source: Continuity equation; API RP 13D: v_a (ft/min) = 24.51 · Q (gpm) / (D² − d²)
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
Unit converter for this formulaLiquid rate · Length · Velocity
- 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 Hydraulics
Output per stroke and flow rate of a single-acting triplex or quintuplex pump from the liner size, stroke length, pump speed and volumetric efficiency.
Total flow area (TFA), jet velocity, bit pressure drop, hydraulic power at the bit and per unit of hole area (HSI), jet impact force.
Pump strokes and time to pump the string and annulus volumes: when the mud reaches the bit, when the bottoms-up (cuttings, gas) reaches surface, and how long a full circulation takes.
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.