Drilling EngineeringDrilling Hydraulics
Bit-to-Surface Lag Time from Annular Volume Formula
Bit-to-Surface Lag Time from Annular Volume calculates lag time for drilling hydraulics workflows in drilling engineering.
How engineers use this formula
Use this formula when the listed inputs (V_AV, PO, SPM) are known and the assumptions behind the cited drilling hydraulics relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Default example
Using the default inputs, t_lag equals 42.301166 min.
V_AVbbl
378.9
PObbl/stk
0.0914
SPMstrokes/min
98
Inputs
V_AV
bblAnnular Volume
PO
bbl/stkPump Output per Stroke
SPM
strokes/minPump Speed
Outputs
t_lag
min
Lag Time
V_AV
bbl
Annular Volume
PO
bbl/stk
Pump Output per Stroke
SPM
strokes/min
Pump Speed
Source and review
reviewedDrillingFormulas. Lag Time for Drilling Business and How to Calculate Theoretical Lag Time; AAPG Wiki Wellsite Math.
Source