Which of the following is NOT listed as a cause of positive skin?

• A. Partial completion
• B. Phase changes relative permeability reduction to main fluid
• C. Turbulence
• D. Low reservoir temperature

Answer: (D)

Positive skin reflects extra pressure drop caused by damage or obstruction in the near-wellbore region that reduces how easily fluids can move into or out of the formation. Partial completion creates barriers or bypassed zones near the well, adding resistance and increasing the skin value. When phase changes occur and relative permeability to the main produced fluid drops, the effective permeability near the well diminishes, again raising the skin. Turbulence from high flow rates can cause formation damage or fines movement around the wellbore, contributing to a positive skin as well. Low reservoir temperature, by itself, doesn’t form the near-wellbore damage mechanisms that define positive skin, so it isn’t listed as a cause in the standard factors.