What is the dimensionless factor that determines the production efficiency of a well, where positive values indicate damage and negative values indicate enhanced productivity?

What is the dimensionless factor that determines the production efficiency of a well, where positive values indicate damage and negative values indicate enhanced productivity?

• A. Skin
• B. Porosity
• C. Permeability
• D. Formation Thickness

Answer: (A)

Skin factor is the dimensionless parameter that captures how the near-wellbore region affects production. It quantifies pressure losses or gains caused by damage, fines plugging, or incomplete cleanup around the well, and conversely by stimulation that improves flow. Positive values indicate extra resistance near the well, reducing production, while negative values reflect enhanced productivity from stimulated flow paths. In the standard radial-flow equation for a well, the production rate depends on the pressure drop divided by μ times [ln(r_e/r_w) + s], where s is the skin. This term acts as an extra, dimensionless adjustment to the flow path length, effectively changing the ease with which fluids move toward the well. Because it is added to a logarithmic term and can be either positive or negative, it embodies a sign-changing, dimensionless measure of near-wellbore conditions. The other properties—porosity, permeability, and formation thickness—affect overall reservoir potential but do not function as the near-well, sign-changing adjustment described by the skin factor.

Skin factor is the dimensionless parameter that captures how the near-wellbore region affects production. It quantifies pressure losses or gains caused by damage, fines plugging, or incomplete cleanup around the well, and conversely by stimulation that improves flow. Positive values indicate extra resistance near the well, reducing production, while negative values reflect enhanced productivity from stimulated flow paths. In the standard radial-flow equation for a well, the production rate depends on the pressure drop divided by μ times [ln(r_e/r_w) + s], where s is the skin. This term acts as an extra, dimensionless adjustment to the flow path length, effectively changing the ease with which fluids move toward the well. Because it is added to a logarithmic term and can be either positive or negative, it embodies a sign-changing, dimensionless measure of near-wellbore conditions. The other properties—porosity, permeability, and formation thickness—affect overall reservoir potential but do not function as the near-well, sign-changing adjustment described by the skin factor.