Plunger lift is an economical artificial lift method to solve the liquid loading problem in gas wells. Because of the inevitable annular gap between plunger and tube wall, the liquid above plunger may leak downward and the gas may slip upward during lifting process. How to quantitatively describe the gas-liquid counter-current flow sealing property is still challenging to optimize the plunger lift method. In this paper, the liquid leakage and gas slippage were observed experimentally. The transient physical models for gas and liquid leakage were proposed and verified.
Most gas wells produce liquid such as water and hydrocarbon condensate throughout the life cycles. Both gas and liquid are originally produced to wellhead if the gas velocity is high enough to lift the coproduced liquids up the tubing1. With gas field becoming mature and gas production rate reducing below the critical rate, liquid accumulates in the bottom of the well and imposes a back pressure on the reservoir, which is called liquid loading in oil and gas industries2–4.