Pore pressure increase due to fluid activity (Mody and Hale)
Input(s)
\(E_{m}\): Membrane Efficiency (dimensionless)
R: Gas Constant (psi/mol K)
T: Temperature \((\mathrm{K})\)
\(\mathrm{V}\): Volume \(\left(\mathrm{ft}^{3}\right)\)
\(A_{p}\): Pore Fluid Activity (dimensionless)
\(A_{m}\): Mud Activity (dimensionless)
Output(s)
\(\delta P\): Pore Pressure Increase \((\mathrm{psi})\)
Formula(s)
\[
\delta P=\mathrm{E}_{\mathrm{m}} *\left(\frac{\mathrm{R} * \mathrm{~T}}{\mathrm{~V}}\right) * \ln \left(\frac{\mathrm{A}_{\mathrm{p}}}{\mathrm{A}_{\mathrm{m}}}\right)
\]
Reference(s)
Mark D. Zoback, Reservoir Geomechanics, Cambridge University Press, UK, Page: 321.