Reservoir EngineeringWell Performance

Giger-Karcher Horizontal Well Critical Rate Formula

q_c=\frac{k_hh^2g\Delta\rho}{B\mu L}\left[1-\frac{1}{6}\left(\frac{h}{L}\right)^2\right]

Giger-Karcher Horizontal Well Critical Rate calculates critical oil rate for well performance workflows in reservoir engineering.

Calculate

How engineers use this formula

Use this formula when the listed inputs (k_h, h, g, Delta_rho, B, mu, 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_c equals 65.360233 m3/day.

k_hmD

100

gm/s2

9.80665

Delta_rhog/cc

0.2

BRB/STB

1.2

mumPa s

500

Inputs

k_h

Horizontal Permeability

h

Oil Column Thickness

g

m/s2

Acceleration of Gravity

Delta_rho

g/cc

Specific Gravity Difference

B

RB/STB

Oil Formation Volume Factor

mu

mPa s

Oil Viscosity

L

Distance Between Lines of Horizontal Wells

Outputs

q_c

m3/day

Critical Oil Rate

k_h