Drilling EngineeringWell Control
Hydrostatic Pressure in Annulus Due to Slug Formula
Hydrostatic Pressure in Annulus Due to Slug calculates hydrostatic pressure for well control workflows in drilling engineering.
How engineers use this formula
Use this formula when the listed inputs (V_a, V_s, W_s, W_m) are known and the assumptions behind the cited well control 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, P equals 416 psi.
V_aft/bbl
100
V_sbbl
20
W_sppg
16
W_mppg
12
Inputs
V_a
ft/bblAnnular Capacity as Length per Barrel
V_s
bblSlug Volume
W_s
ppgSlug Weight
W_m
ppgMud Weight
Outputs
P
psi
Hydrostatic Pressure
V_a
ft/bbl
Annular Capacity as Length per Barrel
V_s
bbl
Slug Volume
W_s
ppg
Slug Weight
W_m
ppg
Mud Weight
Source and review
reviewedLapeyrouse, N.J. 2002. Formulas and Calculations for Drilling, Production and Workover, 2nd Edition, Page 36.
Source