Abstract: Liquid is lifted from a well by a fluid displacement device moves within a production tubing and which maintains a seal against the production tubing during movement. The fluid displacement device is moved up and down within the production tubing between the well bottom and the earth surface by applying gas to create opposite relative pressure differentials across the fluid displacement device. Preferably the pressure differential is obtained from gas supplied from the well of supplied at natural formation pressure.

Abstract: Liquid is accumulated above fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing, and upward movement of the fluid displacement device is initiated to pump liquid and gas from a well, by different magnitudes of differential pressure created at the well bottom. Preferably the different magnitudes of differential pressure are created by fluid passageway is having different cross-sectional areas.