On a gas-oil relative permeability curve at what point will gas relative permeability begin to increase above 0?

On a gas-oil relative permeability curve at what point will gas relative permeability begin to increase above 0?

• A. Onset Gas Permeability
• B. Gas Breakthrough
• C. Gas Saturation Point
• D. Critical Gas Saturation

Answer: (B)

The key idea is that relative permeability to a phase becomes nonzero only when that phase forms a continuous path through the rock. Early on, gas exists as disconnected pockets, so there’s no connected path for gas to flow and the gas relative permeability is effectively zero. The moment the injected gas creates a continuous path from input to output—i.e., it breaks through to the outlet—the gas can flow, and the relative permeability to gas begins to rise from zero. So the point at which the curve first shows gas relative permeability > 0 is the breakthrough point, the moment the gas path spans the core. The other terms describe related thresholds, but breakthrough captures the actual onset of macroscopic gas flow observed in the curve.

The key idea is that relative permeability to a phase becomes nonzero only when that phase forms a continuous path through the rock. Early on, gas exists as disconnected pockets, so there’s no connected path for gas to flow and the gas relative permeability is effectively zero. The moment the injected gas creates a continuous path from input to output—i.e., it breaks through to the outlet—the gas can flow, and the relative permeability to gas begins to rise from zero. So the point at which the curve first shows gas relative permeability > 0 is the breakthrough point, the moment the gas path spans the core. The other terms describe related thresholds, but breakthrough captures the actual onset of macroscopic gas flow observed in the curve.