Which term describes the threshold at which gas begins to contribute to flow in a gas-oil system?

Which term describes the threshold at which gas begins to contribute to flow in a gas-oil system?

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

Answer: (D)

The main idea being tested is when the gas phase becomes mobile enough to contribute to flow in a gas-oil system. In a porous reservoir, gas must form a connected pathway through the pore space so it can move and carry flow; this happens only after the gas saturation reaches a certain level where the gas relative permeability becomes appreciable. That specific level is the critical gas saturation—the threshold at which gas starts to flow and influence production, not merely exist as isolated pockets. So gas begins to contribute to flow once the gas saturation crosses this critical point, allowing gas to form continuous channels and displace oil toward the well.

The main idea being tested is when the gas phase becomes mobile enough to contribute to flow in a gas-oil system. In a porous reservoir, gas must form a connected pathway through the pore space so it can move and carry flow; this happens only after the gas saturation reaches a certain level where the gas relative permeability becomes appreciable. That specific level is the critical gas saturation—the threshold at which gas starts to flow and influence production, not merely exist as isolated pockets.

So gas begins to contribute to flow once the gas saturation crosses this critical point, allowing gas to form continuous channels and displace oil toward the well.