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S = \frac{p_{wf\rm ref}(t, r_w) - p_{\rm refwf}(t, r_w)}{ \left[ r \cdot \frac{\partial p_{\rm ref}}{\partial r} \right]_{r=r_w} } |
It can be interpreted as the dimensionless ratio of linear-average pressure gradient between wellbore axis () and wellbore radius to the actual pressure gradient at wellbore radius:
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S = \frac{left[ \frac{p_{wf\rm ref}(t, r_w) - p_{\rm refwf}(t, r_w)}{ r_w } }{\right]
\Big/
{ \left[ \frac{ \partial p_{\rm ref}}{\partial r} \right]_{r=r_w}} |
By definition the skin-factor is a pressure adjustment at the well-reservoir contact and does not affect pressure distribution in reservoir away from wellbore
.
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S_T = S_G + \frac{A_w}{A_{wrc}} \cdot S_M |
where
Based on definition the wellbore pressure dynamics
of the well with
skin-factor can be writen as:
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p_{wf}(t) = - \frac{q_t}{2 \pi \sigma} \, S + p_{\rm ref}(t,r_w) |
where
See Also
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Petroleum Industry / Upstream / Subsurface E&P Disciplines / Well Testing / Pressure Testing
[ Well & Reservoir Surveillance ]
[ Skin-factor (geometrical) ][ Skin-factor (mechanical) ]