US Patent 11180977 Plunger lift method

A plunger includes a sleeve having a passage therethrough and a valve member in the passage. When the plunger falls in a production string of a hydrocarbon well, the valve member is open and allows gas flow through the plunger. When the plunger contacts a liquid slug in the production string, the valve closes so that pressure from below reverses movement of the plunger so it pushes liquid above the plunger toward the earth's surface and ultimately to a well head where liquid and gas are separated.