Drilling EngineeringWell Control
Surface Test Pressure Required to Frac the Formation Formula
Surface Test Pressure Required to Frac the Formation calculates surface test pressure for well control workflows in drilling engineering.
How engineers use this formula
Use this formula when the listed inputs (FG, D, rho_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_ST equals 2,260 psi.
FGpsi/ft
0.85
Dft
10000
rho_mppg
12
Inputs
FG
psi/ftFracture Gradient
D
ftDepth
rho_m
ppgMud Density
Outputs
P_ST
psi
Surface Test Pressure
FG
psi/ft
Fracture Gradient
D
ft
Depth
rho_m
ppg
Mud Density
Source and review
reviewedCementing Handbook, Suman, G.O. Jr., Ellis, R.C. (1977)
Suman, G.O. Jr. and Ellis, R.C. 1977. Cementing Handbook, World Oil, Page 69.
Source