In reservoir engineering, what term describes the extra pressure drop near the wellbore due to skin effects?

• A. Mobility
• B. Viscosity
• C. Skin factor
• D. Porosity

Answer: (C)

Near a well, disturbances in the flow due to damage, perforations, filtration, or stimulation create an extra pressure drop that isn’t explained by the bulk reservoir properties alone. This additional loss is captured by the skin factor, a dimensionless number added to the radial-flow pressure equation. A positive skin increases the pressure drop near the well, while a negative skin indicates stimulation and reduced drop. Mobility, viscosity, and porosity influence overall flow but don’t quantify this extra near-wellbore loss. So the term describing the extra pressure drop due to skin effects is the skin factor.