Pore pressure increase due to given fluid activity contrast (Mody and Hale)
Input(s)
\(\mathrm{E}_{\mathrm{m}}\): Membrane Efficiency (dimensionless)
\(\mathrm{R}\): Gas Constant (dimensionless)
\(\mathrm{T}\): Temperature \((\mathrm{K})\)
\(\mathrm{V}\): Molar Volume of Water \((\mathrm{L} / \mathrm{mol})\)
\(\mathrm{A}_{\mathrm{p}}\): Pore Fluid Activity (dimensionless)
\(\mathrm{A}_{\mathrm{m}}\): Mud Activity (dimensionless)
Output(s)
\(\mathrm{dP}\): Pore Pressure Increase (psi)
Formula(s)
\[
\mathrm{dP}=\mathrm{Em} *\left(\mathrm{R} * \frac{\mathrm{T}}{\mathrm{V}}\right) * \log \left(\frac{\mathrm{Ap}}{\mathrm{Am}}\right)
\]
Reference(s)
Mark D. Zoback, Reservoir Geomechanics, Cambridge University Press, UK, Page: 105.