Which process involves injecting gas under a column of liquid (usually above a standing valve) to displace that slug of liquid to the surface?

Which process involves injecting gas under a column of liquid (usually above a standing valve) to displace that slug of liquid to the surface?

• A. Gas Lift
• B. Intermittent Gas Lift
• C. Foam Propulsion
• D. Gas Washing

Answer: (B)

The idea being tested is how gas lift creates lifting force by forming and pushing liquid slugs with gas that is injected in pulses. In intermittent gas lift, gas is injected under a column of liquid and is often trapped above a standing valve. The trapped gas builds pressure until it pushes a slug of liquid upward to the surface. When that slug reaches surface, the gas releases and the cycle repeats, creating a rhythmic lifting of liquid up the well. This differs from continuous gas lift, where gas is injected steadily and the lift comes from a lighter, continuous gas–liquid column rather than discrete slugs. Foam propulsion and gas washing aren’t used to move slugs like this in well lifting scenarios. So, the process described—injecting gas in bursts under the liquid to displace a slug to surface—is intermittent gas lift.

The idea being tested is how gas lift creates lifting force by forming and pushing liquid slugs with gas that is injected in pulses. In intermittent gas lift, gas is injected under a column of liquid and is often trapped above a standing valve. The trapped gas builds pressure until it pushes a slug of liquid upward to the surface. When that slug reaches surface, the gas releases and the cycle repeats, creating a rhythmic lifting of liquid up the well.

This differs from continuous gas lift, where gas is injected steadily and the lift comes from a lighter, continuous gas–liquid column rather than discrete slugs. Foam propulsion and gas washing aren’t used to move slugs like this in well lifting scenarios.

So, the process described—injecting gas in bursts under the liquid to displace a slug to surface—is intermittent gas lift.