Normalised dimensionless difference between the sandface bottomhole pressure (BHP)
and the
sandface r
eservoir pressure | LaTeX Math Inline |
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| body | \displaystyle p({\bf r}, t) |_{{\bf r} \in \Gamma_s} |
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at the boundary
of
damaged reservoir zone :
| LaTeX Math Block |
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S = \frac{2 \pi \sigma}{q_t} \cdot \left[ p_{wf}(t) - p({\bf r}, t) |_{{\bf r} \in \Gamma_s} \right] |
where
It quantitatively characterises permeability change in a thin layer around the well or fracture plane caused by stimulation or deterioration during production, injection or well intervention.
It contributes to the total skin estimated in transient well testing.
For the radial-symmetric permeability change around the well it can be estimated from Hawkins equation:
| LaTeX Math Block |
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S_M = \left ( \frac{k}{k_s} - 1 \right ) \ \ln \left ( \frac{r_s}{r_w} \right ) |
where
Definition suggest that
The most popular practical range of skin-factor variation is
.
Formula | LaTeX Math Block Reference |
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| anchor | pwf |
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| page | 1DR pressure diffusion of low-compressibility fluid |
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provides a good example how mechanical skin-factor affects pressure dynamics.
