@wikipedia
A pore volume
fraction of bulk rock volume containing the hydrodynamically connected fluids (also called free fluids) within each pore element:| LaTeX Math Block |
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\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 | LaTeX Math Inline |
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| body | --uriencoded--\phi_%7B\rm opn%7D |
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subject to condition:
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\phi_e = \phi_{\rm opn} + \phi_{\rm cls} |
Effective porosity is a function of reservoir pressure at a given location
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\phi_e(\mathbf{r}, \ p) = \phi_{e0}(\mathbf{r}) \exp \left[ \int_{p_i}^p c_r(p) \, dp \right] |
where
Since the pore compressibility is very low (~ cr = 0.5 ÷ 1.5 GPa-1) for all subsurface rocks in petroleum reservoirs the | LaTeX Math Block Reference |
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can be written as:
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\phi_e(\mathbf{r}, \ p) = \phi_{e0}(\mathbf{r}) \cdot \big[ 1 + c_r(p) \, (p-p_i) \big] |
Most Subsurface E&P Disciplines (except Petrophysics) usually omit index "e" and denote Effective porosity as .
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 ]
