Rotation of maximum principal stress near wellbore

Input(s)

A: Stress Field Direction (dimensionless)

$\mathrm{P}_{\mathrm{p}}$: Change in Pore Pressure $(\mathrm{psi})$

$\theta$: Fault Orientation (degrees)

$\mathrm{S}_{\mathrm{hmax}}$: Maximum Principle Stress (psi)

$\mathrm{S}_{\mathrm{hmin}}$: Minimum Principle Stress (psi)

Output(s)

$\gamma$: Rotation (degrees)

Formula(s)

$$ \gamma=0.5 * \operatorname{atan}\left(\frac{\mathrm{A} * \mathrm{P}_{\mathrm{p}} * \sin (2 * \theta)}{\mathrm{S}_{\mathrm{hmax}}-\mathrm{S}_{\mathrm{hmin}}+\mathrm{A} * \mathrm{P}_{\mathrm{p}} * \cos (2 * \theta)}\right) $$

Reference(s)

Mark D. Zoback, Reservoir Geomechanics, Cambridge University Press, UK, Page: 393.