TABLE OF CONTENTS Plunger lift operates on a relatively simple cycle as illustrated in Figure 7-4. Figure 7-5 shows in more detail the casing and tubing and bottomhole pressures throughout one complete plunger cycle. The numbers on top of Figure 7-4 labeling the steps of the cycle are also provided on the figure for clarity.
The well is closed, and pressure in the casing is building. When the pressure is enough to lift the plunger and the liquids to the surface at a reasonable velocity ( 750 fpm) against the surface pressure, the surface tubing valve will open
The valve opens, and the plunger and liquid slug rise. The gas in the annulus expands into the tubing to provide the lifting pressure. Also, the well is producing some during the rise time to add to the energy required to lift the plunger and liquid.
The liquid reaches the surface and travels down the flowline. The plunger is held at the surface by pressure and flow. The gas is allowed to flow
The flow velocity begins to decrease, and liquids begin to accumulate in the bottom of the well. The casing pressure begins to rise, indicating a larger pressure drop in the tubing. If flow is allowed to continue too long, a "too large" liquid slug will accumulate in the bottom of the well, requiring a high casing buildup pressure to lift it
The valve is shut, and the plunger falls. The liquids are mainly at the bottom of the...
