Fluids cause formation damage under which condition?

Fluids cause formation damage under which condition?

• A. Increase in reservoir pressure
• B. Increase in sodium concentration
• C. Change in apparent viscosity of the oil phase or a change in relative permeability
• D. Decrease in formation porosity

Answer: (C)

Formation damage happens when fluids change how easily fluids can move through the rock. The clearest way this occurs is when the oil’s apparent viscosity changes, or when the relative permeability to the oil–water two-phase system changes. If the injected or invading fluid makes oil appear more viscous or shifts the relative permeability so that the oil mobility is reduced (or water mobility increases), flow is hindered and permeability near the wellbore or in the invaded zone decreases. This impairment of flow, not a simple loss of pore space, is what we mean by formation damage in this context.

Formation damage happens when fluids change how easily fluids can move through the rock. The clearest way this occurs is when the oil’s apparent viscosity changes, or when the relative permeability to the oil–water two-phase system changes. If the injected or invading fluid makes oil appear more viscous or shifts the relative permeability so that the oil mobility is reduced (or water mobility increases), flow is hindered and permeability near the wellbore or in the invaded zone decreases. This impairment of flow, not a simple loss of pore space, is what we mean by formation damage in this context.