API RP 14E Two-Phase Flowline Pressure Drop Formula
API RP 14E Two-Phase Flowline Pressure Drop calculates two-phase flowline pressure drop per 100 ft for well performance workflows in production engineering.
How engineers use this formula
Use this formula when the listed inputs (f, W, D_i, rho_m) are known and the assumptions behind the cited well performance 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, DeltaP_100 equals 3.9896 psi/100 ft.
0.0196
46482.8
3.15
11.5
Inputs
f
dimensionlessMoody Friction Factor
W
lb/hrTotal Liquid Plus Vapor Weight Flow Rate
D_i
inPipe Inside Diameter
rho_m
lb/ft3Gas-Liquid Mixture Density
Outputs
DeltaP_100
Two-Phase Flowline Pressure Drop per 100 ft
f
Moody Friction Factor
W
Total Liquid Plus Vapor Weight Flow Rate
D_i
Pipe Inside Diameter
rho_m
Gas-Liquid Mixture Density
Source and review
reviewedAPI RP 14E Section 2.5 pressure-drop equation for gas/liquid two-phase steel piping.
Source