Steady-State Radial Liquid Flow Rate Calculator
Enter reservoir permeability, net pay, pressure drawdown, viscosity, formation volume factor, radii, and skin. The calculator returns radial liquid flow rate.
Calculation context and source notes
Steady-state radial liquid flow rate estimates oil or liquid inflow toward a well from permeability, thickness, pressure drawdown, viscosity, formation volume factor, drainage radius, wellbore radius, and skin.
Use it for quick radial-flow inflow screening when boundary pressure is stable and single-phase liquid assumptions are acceptable.
Solves for
q_o (STB/day)
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Formula, variables, and sourceRelated source-backed guides
Formula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns q_o = 735.844574 STB/day. Defaults demonstrate the implementation; they are not recommended field values.
100
50
3000
2500
2
1.2
1000
0.328
2
Input definitions
k
mDPermeability
h
ftNet Pay Thickness
p_e
psiExternal Boundary Pressure
p_wf
psiFlowing Bottom-Hole Pressure
mu_o
cPOil Viscosity
B_o
bbl/STBOil Formation Volume Factor
r_e
ftDrainage Radius
r_w
ftWellbore Radius
s
dimensionlessSkin Factor
Output definitions
q_o
Oil Flow Rate
Engineering use, assumptions, and limits
Use it for quick radial-flow inflow screening when boundary pressure is stable and single-phase liquid assumptions are acceptable.
Assumptions
- Flow is steady state, radial, and single-phase liquid.
- Reservoir pressure and flowing bottomhole pressure define a representative drawdown.
- Permeability, thickness, viscosity, formation volume factor, and skin are representative around the well.
Limitations
- Does not handle transient flow, multiphase IPR curvature, boundary-dominated decline, or tubing/surface constraints.
- Accuracy depends strongly on radius and skin assumptions.
Common mistakes
- Using wellhead pressure instead of flowing bottomhole pressure.
- Ignoring skin when near-wellbore damage or stimulation is important.
- Applying steady-state assumptions before the reservoir has reached steady behavior.
Source and record status
Source metadata identifies the relationship implemented by the calculator. Check the cited edition, unit basis, and scope against the engineering case before operational use.
Lyons, W.C. 2010. Working Guide to Reservoir Engineering. Darcy radial liquid-flow equation.
Open source reference