Wellbore Skin Effect

by Glenn M. Duffield, President, HydroSOLVE, Inc.


Moench (1997) provides a useful definition of wellbore skin for a finite-diameter well that derives from the heat flow literature. According to Moench, "the spatial average of head in the well bore, hw, is related to the average head in the aquifer adjacent to the pumped well screen, h*," by the following equation:

Wellbore skin equation

where Ks is wellbore skin hydraulic conductivity, ds is wellbore skin thickness, Kr is radial hydraulic conductivity in the aquifer, and rw is well radius. In this definition, the storage capacity of the skin is neglected.

Moench (1997) also defines a dimensionless wellbore skin factor as follows:

Sw = Krds/Ksrw

See also: pumping tests