Conventional DST design without a water cushion (collapse pressure calculation)

Input(s)

$\mathrm{g}_{\mathrm{w}}$: Water Gradient $(\mathrm{psi} / \mathrm{ft})$

$\mathrm{W}_{\mathrm{m}}$: Mud Weight (lbm/gal)

$\mathrm{D}_{\mathrm{c}}$: Depth $(\mathrm{ft})$

$\mathrm{F}_{\mathrm{d}}$: Design Factor (dimensionless)

$\mathrm{W}_{\mathrm{w}}$: Water Weight (lbm/gal)

Output(s)

$\mathrm{p}_{\text {collapse: }} \quad$ Collapse Pressure (psi)

Formula(s)

$$ \mathrm{p}_{\text {collapse }}=\frac{\mathrm{g}_{\mathrm{w}} * \mathrm{~W}_{\mathrm{m}} * \mathrm{D}_{\mathrm{c}} * \mathrm{~F}_{\mathrm{d}}}{\mathrm{W}_{\mathrm{w}}} $$

Reference(s)

Lee, J., Rollins, J. B., \& Spivey, J. P. (2003). Pressure Transient Testing (Vol. 9). Richardson, Texas: Society of Petroleum Engineers, Page: 153.