Part of the bulk rock volume V_r containing the hydrodynamically connected fluids (also called free fluids) within each pore element with total volume V_f:
| (1) | \phi_e = \frac{V_f}{V_r} |
Although the fluid inside the pore is movable but some pores maybe isolated from each other and do not contribute to rock permeability.
This splits the effective pore volume into two components: open pore volume and closed pore volume:
| V_\phi = V_{\rm open} + V_{\rm closed} |
The log name is PHIE.
Effective porosity is a function of reservoir pressure at a given location
p({\bf r})
| (2) | \phi(\mathbf{r}, \ p) = \phi_0(\mathbf{r}) \exp \left[ - \int_{p_i}^p c_r(p) \, dp \right] |
where
See also
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petrophysics (PP) / Volumetric Rock Model
[ Basic reservoir properties ]