Patent ID: 8181706
Filing Date: 2012-05-22
Classification: E21B,F04B

Abstract:
1. A plunger lift system for lifting formation liquids from a well producing through a wellbore communicating with a hydrocarbon formation, comprising: (a) a free piston with a sleeve including an open end, an opposite end, a hollow passage therebetween to accumulate the formation liquids and a piston face on the opposite end, the piston face being an end wall that extends across the entirety of the opposite end to close the hollow passage; (b) the free piston having an external diameter that is substantially similar to the inner diameter of the wellbore; (c) the free piston being moveable between a top of the wellbore and a lower portion of the wellbore; and (d) the free piston including at least a portion thereof formed of a material that is buoyant relative to the formation liquids.