Vertical well critical rate correlations - Craft and Hawkins method

Input(s)

b: Penetration Ratio, $\left(h_{p} / \mathrm{h}\right)$ (dimensionless)

$r_{e}$: Radius of Drainage $(\mathrm{ft})$

$r_{w}$: Radius of Wellbore $(\mathrm{ft})$

$h_{p}$: Thickness of Perforated interval (ft)

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

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

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

$k_{o}$: Effective Oil Permeability $(\mathrm{mD})$

$p_{w s}$: Static Well Pressure Corrected to the Middle of the Producing Interval (psi)

$p_{w f}$: Flowing Well Pressure at the Middle of the Producing Interval (psi)

Output(s)

PR: Productivity Ratio (dimensionless)

$q_{o}$: Critical Rate (Maximum Oil Rate without Coning) (STB/day)

Formula(s)

$$ \begin{gathered} P R=b *\left(1+7 *\left(\frac{r_{w}}{2 * b * h}\right)^{0.5} * \cos \left(b * 90^{\circ}\right)\right) \\ q_{o}=\frac{0.007078 * k_{o} * h *\left(p_{w s}-p_{w f}\right)}{\mu_{o} * B_{o} * \ln \left(\frac{r_{e}}{r_{w}}\right)} * P R \end{gathered} $$

Reference(s)

Joshi, S. D. 1991, Horizontal Well Technology. Tulsa, Oklahoma: PennWell Publishing Company. Chapter: 8 , Page: 254.