Rotation of maximum principal stress near wellbore (Zoback \ Day-Lewis)
Input(s)
A: Constant a Value (dimensionless)
\(\Delta\): Fault Orientation (degrees)
q: Ratio of Pore Pressure to Differential Stress (dimensionless)
Output(s)
\(\gamma\): Stress Rotation (radian)
Formula(s)
\[
\gamma=0.5 * \operatorname{atan}\left(\mathrm{A} * \mathrm{q} * \frac{\sin (2 * \Delta)}{1+\mathrm{A} * \mathrm{q} * \cos (2 * \Delta)}\right)
\]
Reference(s)
Mark D. Zoback, Reservoir Geomechanics, Cambridge University Press, UK, Page: 393.