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.