Stress at edge of wellbore breakout
Input(s)
\(\mathrm{C}_{\mathrm{o}}\): Wellbore Strength (psi)
\(\mathrm{P}_{\mathrm{p}}\): Pore Pressure \((\mathrm{psi})\)
P: Drawdown Differential in Pressure (psi)
\(\sigma_{\mathrm{t}}\): Thermally Induced Stress (psi)
\(\mathrm{w}_{\mathrm{b}}\): Wellbore Breakout (degrees)
\(\mathrm{S}_{\mathrm{hmin}}\): Minimum Horizontal Stress (psi)
Output(s)
\(\theta_{\mathrm{b}}\): Breakout Angle (degrees)
\(\mathrm{S}_{\mathrm{hmax}}\): Maximum Principle Stress (psi)
Formula(s)
\[
\begin{gathered}
2 \theta_{\mathrm{b}}=\pi-\mathrm{w}_{\mathrm{b}} \\
\mathrm{S}_{\mathrm{h} \max }=\frac{\left(\left(\mathrm{C}_{\mathrm{o}}\right)+2 * \mathrm{P}_{\mathrm{p}}+\mathrm{P}+\sigma_{\mathrm{t}}\right)-\mathrm{S}_{\mathrm{h} \min } *\left(1+2 * \cos \left(\theta_{\mathrm{b}}\right)\right)}{1-2 * \cos \left(\theta_{\mathrm{b}}\right)}
\end{gathered}
\]
Reference(s)
Mark D. Zoback, Reservoir Geomechanics, Cambridge University Press, UK, Page: 223.