Efros Horizontal Well Critical Rate Formula
Efros Horizontal Well Critical Rate calculates critical oil rate for well performance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (rho_o, rho_w, y_e, h, mu_o, B_o, k_h, L) 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, q_o equals 10.174011 STB/day.
0.8
1.0
500
50
2
1.2
100
1000
Inputs
rho_o
g/ccOil Density
rho_w
g/ccWater Density
y_e
ftHalf of Horizontal Well Spacing
h
ftOil Column Thickness
mu_o
cPOil Viscosity
B_o
RB/STBOil Formation Volume Factor
k_h
mDHorizontal Permeability
L
ftLength of Reservoir
Outputs
q_o
Critical Oil Rate
k_h
Horizontal Permeability
L
Length of Reservoir
B_o
Oil Formation Volume Factor
mu_o
Oil Viscosity
rho_w
Water Density
rho_o
Oil Density
Source and review
reviewedJoshi, S.D. 1991. Horizontal Well Technology. Tulsa, Oklahoma: PennWell Publishing Company, pages 286-295.
Source