Dimensionless value characterising permeability change in a thin layer around the well or fracture plane caused by stimulation or deterioration.

It contributes to the total skin estimated in transient well testing. 

For the radial-symmetric permeability change around a well it can be represented by Hawkins equation:

Definition suggest that
 

• deteriorated near-well reservoir zone  $//<![CDATA[ \begin{array}{l}k_s < k\end{array} //]]>$ is characterized by a positive skin-factor  $//<![CDATA[ \begin{array}{l}S>0\end{array} //]]>$,
   
• improved near-well reservoir zone   $//<![CDATA[ \begin{array}{l}k_s > k\end{array} //]]>$ is characterized by a negative skin-factor  $//<![CDATA[ \begin{array}{l}S< 0\end{array} //]]>$.

Motivation