# Horizontal well critical rate correlations - Efros

## Input(s)

\(\rho_{o}\): Oil Density \((\mathrm{g} / \mathrm{cc})\)

\(\rho_{w}\): Water Density \((\mathrm{g} / \mathrm{cc})\)

\(y_{e}\): Half of Horizontal Well Spacing (ft)

\(\mathrm{h}\): Oil Column Thickness (ft)

\(\mu_{o}\): Oil Viscosity (cP)

\(B_{o}\): Oil Formation Volume Factor (RB/STB)

\(k_{h}\): Horizontal Permeability \((\mathrm{mD})\)

L: Length of Reservoir ( \(\mathrm{ft}\) )

## Output(s)

\(q_{o}\): Critical Oil Rate (STB/day)

## Formula(s)

\[
q_{o}=\left(4.888 * 10^{-4}\right) * k_{h} * h^{2} *\left(\rho_{w}-\rho_{o}\right) * \frac{L}{B_{o} * \mu_{o} *\left(\left(2 * y_{e}+\left(2 * y_{e}\right)^{2}+\frac{h^{2}}{3}\right)^{0.5}\right)}
\]

## Reference(s)

Horizontal Well Technology, Joshi, Page: 286-295.