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This leads to the effect of Porosity Shrinkage.
Since the pore compressibility is very low (~ cϕ = 0.5 ÷ 1.5 GPa-1) and has a weak dependence on reservoir pressure for subsurface rocks in petroleum reservoirs the
can be written as:LaTeX Math Block Reference anchor pher
| LaTeX Math Block | ||||
|---|---|---|---|---|
| ||||
\phi_e(\mathbf{r}, \ p) = \phi_{ei}(\mathbf{r}) \cdot \left[ 1 + c_\phi \, (p-p_i) + 0.5 \, c_\phiphi^2 \, (p-p_i)^2 \right] |
Most Subsurface E&P Disciplines (except Petrophysics) usually omit index "e" and denote Effective porosity as
.LaTeX Math Inline body \phi = \phi_e
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