Critical velocity for change in flow regime
Input(s)
PV: Plastic Viscosity (cP)
YP: Yield Stress or Yield Point \(\left(\mathrm{lb} / 100 \mathrm{ft}^{2}\right)\)
\(\rho_{\mathrm{m}}\): Mud Density (ppg)
\(\mathrm{D}_{\mathrm{i}}\): inside Diameter of Pipe (in.)
Output(s)
\(\mathrm{V}_{\mathrm{c}}\): Critical Velocity \((\mathrm{ft} / \mathrm{s})\)
Formula(s)
\[
\mathrm{V}_{\mathrm{c}}=\frac{(1.08 * \mathrm{PV})+\left(1.08 *\left(\mathrm{PV}+12.34 * \rho_{\mathrm{m}} *\left(\mathrm{D}_{\mathrm{i}}^{2}\right) * \mathrm{YP}\right)^{0.5}\right)}{\rho_{\mathrm{m}} * \mathrm{D}_{\mathrm{i}}}
\]
Reference(s)
Samuel. E Robello. 501 Solved Problems and Calculations for Drilling Operations. Sigma Quadrant. 2015. Houston, Texas, Page: 220.