Which parameter describes the rock's ability to transmit a single fluid in the presence of other fluids?

Which parameter describes the rock's ability to transmit a single fluid in the presence of other fluids?

• A. Effective permeability
• B. Absolute permeability
• C. Porosity
• D. Intrinsic permeability

Answer: (A)

The idea being tested is how to quantify flow in a rock when multiple fluids share the pore space. In a single-fluid (single-phase) case, permeability that matters is the absolute (or intrinsic) permeability—the rock’s inherent ability to transmit that fluid. But when other fluids are present, not all pores are available for the fluid you’re considering, so the actual flow capability is reduced. That real, usable conductivity is captured by the effective permeability: it combines the rock’s absolute permeability with the reduction caused by the other fluids, through the relative permeability for that fluid. In other words, effective permeability = absolute permeability × relative permeability for the fluid, and it represents how easily that particular fluid can move through the rock under multiphase conditions. Porosity describes how much pore space exists, not how easily fluids move through it. Intrinsic permeability is another name for the rock’s inherent ability to transmit a fluid when the rock is fully saturated with that fluid, which ignores the presence of other fluids. So the parameter that best describes transmitting a single fluid in the presence of others is the effective permeability.

The idea being tested is how to quantify flow in a rock when multiple fluids share the pore space. In a single-fluid (single-phase) case, permeability that matters is the absolute (or intrinsic) permeability—the rock’s inherent ability to transmit that fluid. But when other fluids are present, not all pores are available for the fluid you’re considering, so the actual flow capability is reduced. That real, usable conductivity is captured by the effective permeability: it combines the rock’s absolute permeability with the reduction caused by the other fluids, through the relative permeability for that fluid. In other words, effective permeability = absolute permeability × relative permeability for the fluid, and it represents how easily that particular fluid can move through the rock under multiphase conditions.

Porosity describes how much pore space exists, not how easily fluids move through it. Intrinsic permeability is another name for the rock’s inherent ability to transmit a fluid when the rock is fully saturated with that fluid, which ignores the presence of other fluids. So the parameter that best describes transmitting a single fluid in the presence of others is the effective permeability.