Drilling EngineeringWell Control
Surface Pressure During Drill Stem Test Formula
Surface Pressure During Drill Stem Test calculates surface pressure during drill stem test for well control workflows in drilling engineering.
How engineers use this formula
Use this formula when the listed inputs (h, EMW, SG) 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 2,558.14 psi.
hft
10000
EMWppg
12
SGfraction
0.85
Inputs
h
ftTotal Vertical Depth
EMW
ppgEquivalent Mud Weight for Formation Pressure
SG
fractionOil Specific Gravity
Outputs
P
psi
Surface Pressure During Drill Stem Test
h
ft
Total Vertical Depth
EMW
ppg
Equivalent Mud Weight for Formation Pressure
SG
fraction
Oil Specific Gravity
Source and review
reviewedLapeyrouse, N.J. Formulas and Calculations for Drilling, Production and Workover, 2nd Edition, Page 138.
Source