Pressure required to break circulation - Annulus

Input(s)

y: Gel strength of drilling fluid $\left(\mathrm{lb} / 100 \mathrm{ft}^{2}\right)$

$\mathrm{L}$: Length of Drill String $(\mathrm{ft})$

Dh: Diameter of hole (in.)

Dp: Diameter of drill pipe (in.)

Output(s)

$P_{g s}$: Pressure to overcome mud's gel strength inside annulus (psi)

Formula(s)

$$ P_{g s}=\frac{y}{300 *(D h-D p)} * L $$

Reference(s)

Formulas and Calculations for Drilling, Production and Workover, Second Edition, Lapeyrouse, Page: 79.