Which factor is explicitly listed as influencing relative permeability but is not a typical fluid property?

• A. Pore Geometry
• B. Wettability
• C. Saturations/Saturation History
• D. Fluid Distribution

Answer: (C)

Relative permeability depends on how the pore space is occupied by each fluid and how that occupancy came to be. Saturations tell you how much of the pore space is filled with a given fluid, and saturation history describes the sequence of events (drainage or imbibition) that led to that occupancy. This history matters because it changes the connectivity of the fluid phases and creates hysteresis in the flow behavior—so the same saturation can yield different relative permeabilities depending on how you got there. These factors are not intrinsic fluid properties like viscosity or density; they’re properties of the fluid–rock system. Pore geometry and wettability set the rock’s framework, while fluid distribution is a consequence of saturation and capillary effects. Because saturations and saturation history directly influence relative permeability and are not typical fluid properties, they’re the best fit.