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.