This term, often used in relation to EOR flooding, describes the effect of one fluid flowing through a porous media and displacing fluid of a different viscosity.

This term, often used in relation to EOR flooding, describes the effect of one fluid flowing through a porous media and displacing fluid of a different viscosity.

• A. Spreading
• B. Channeling
• C. Displacement
• D. Fingering

Answer: (D)

Viscous fingering describes what happens when a fluid with lower viscosity moves through a porous medium containing a more viscous fluid. The viscosity contrast makes the interface between the two fluids unstable, so the displacing fluid doesn’t push the other fluid out evenly. Instead, it forms finger-like streams that advance ahead of the rest, bypassing much of the fluid and creating an irregular front. In EOR flooding, this leads to poor sweep efficiency because the displacing fluid channels through high-permeability paths and leaves behind oil in the banked regions. The term specifically captures that irregular, branched front pattern, which is why it’s the best fit. Spreading implies a smoother, more uniform expansion; channeling points to flow through preferential paths but doesn’t inherently describe the instability with a viscosity contrast; displacement is a general word for one fluid pushing another and doesn’t name the unstable front pattern.

Viscous fingering describes what happens when a fluid with lower viscosity moves through a porous medium containing a more viscous fluid. The viscosity contrast makes the interface between the two fluids unstable, so the displacing fluid doesn’t push the other fluid out evenly. Instead, it forms finger-like streams that advance ahead of the rest, bypassing much of the fluid and creating an irregular front. In EOR flooding, this leads to poor sweep efficiency because the displacing fluid channels through high-permeability paths and leaves behind oil in the banked regions. The term specifically captures that irregular, branched front pattern, which is why it’s the best fit. Spreading implies a smoother, more uniform expansion; channeling points to flow through preferential paths but doesn’t inherently describe the instability with a viscosity contrast; displacement is a general word for one fluid pushing another and doesn’t name the unstable front pattern.