A plunger lift is a type of pumping system used in natural gas wells. These lifts serve as one of the most popular gas well deliquification techniques, and are designed to remove liquid and other contaminants from the gas. Without some type of deliquification to remove moisture, gas wells eventually slow or cease production entirely.
Each plunger lift consists of a steel cylinder, or plunger, which is inserted within the well casing. To start removing fluid from the well, workers use a special surface valve to shut down all drilling and pumping operations. When the well is turned off, the natural gas builds up beneath the plunger, leading to an increase in pressure within the well. This pressure forces all liquid to remain above the plunger, and the plunger itself acts as a natural plug to separate the gas from moisture.
Once pressure within the well has reached a specified level, the valve is reopened to resume drilling and pumping. The excess pressure creates a tremendous force, which lifts the plunger rapidly to the top of the casing. As it rises, it forces any liquid or moisture out through a vent or exhaust area. The plunger blocks the gas from escaping through this vent, and instead forces it through a standard processing pipe for collection or sale. After the gas is released from the well, the plunger lift drops back down into the well casing to repeat the process.
A plunger lift may rely on a variety of operating principles. Some utilize a simple timer, which opens and closes the valve at specific intervals to release gas and fluid. Others incorporate a more advanced microprocessor to time the plunger lift more precisely. These processors measure factors like gas flow rate, temperature, and pressure to determine the optimal time to open the valve and lift the plunger. This helps to maximize natural gas production while minimizing problems with fluid within the well.
Plunger lift systems offer many advantages over traditional deliquification techniques. By removing moisture and keeping it away from the natural gas, these lifts extend the life of a well and keep it from "running dry." They are also cheaper and easier to operate than alternative methods, such as blowback systems. Finally, a plunger lift helps to product the environment by limiting methane gas emissions from the well. Methane gas is a greenhouse gas, which means it contributes to problems with the ozone layer and global warming.