A pore volume V_\phi fraction of bulk rock volume V_r containing the hydrodynamically connected fluids (also called free fluids) within each pore element:
\phi_e = \frac{V_\phi}{V_r} |
The log name is PHIE.
The reason to introduce this concept is that a part of the actual inter-grain void is filled with shale thus reducing the actual volume available for fluids.
It splits into two components: open porosity \phi_{\rm con} and closed porosity \phi_{\rm cls}:
\phi_e = \phi_{\rm con} + \phi_{\rm cls} |
Effective porosity is a function of reservoir pressure at a given location
p({\bf r})
(1) | \phi(\mathbf{r}, \ p) = \phi_0(\mathbf{r}) \exp \left[ - \int_{p_i}^p c_r(p) \, dp \right] |
where
c_r(p) | pore compressibility (see also Pore compressibility @model ) |
p_i | initial formation pressure |
See also
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petrophysics (PP) / Volumetric Rock Model
[ Basic reservoir properties ] [ Pore volume ] [ Connected pore volume ] [ Closed pore volume ] [ Porosity ] [ Open porosity ] [ Closed porosity ]
[ Pore compressibility @model ]