Circulation times: surface to bit, bottoms up, full circulation
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.
n_sb = V_s / q; t_sb = n_sb / Nn_bu = V_a / q; t_bu = n_bu / Nn_c = n_sb + n_bu; t_c = t_sb + t_buSurface lines are not included. Cuttings rise slower than the mud (slip), so the actual lag is longer — check it with a carbide or tracer test.
Source: Volume balance; IWCF/IADC kill sheet (surface-to-bit and bottoms-up strokes)
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
Unit converter for this formulaLiquid volume · Time
- m³1
- 10³ m³0.001
- 10⁶ m³1·10⁻⁶
- L1,000
- bbl6.28981
- Mbbl0.00628981
- MMbbl6.28981·10⁻⁶
- ft³35.3147
- US gal264.172
- n_bu — Bottoms-up strokes–strokes
- t_sb — Surface-to-bit time–
- n_sb — Surface-to-bit strokes–strokes
- t_c — Full circulation time–
- n_c — Full circulation strokes–strokes
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.
Average mud velocity in the annulus between the hole (or casing) and the pipe at a given pump rate.
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.