Ball plunger lift system for high deviated wellbores

The invention generally relates to a plunger lift system that can be used in all type of oil and gas wells including wells of vertical, highly deviated, S-curved or horizontal bores. The plunger lift system has a ball-shaped plunger. Multiple ball plungers may be used for a single operation to lift liquid out of a wellbore. Certain embodiments further include a surface lubricator, associated piping and valve systems in communication with a pipeline, a surface control system and related equipment, a downhole bumper spring assembly and/or retrieval device having a magnet to retrieve the ball plunger of the wellbore if and when needed. The invention also relates to ball-shaped plungers and to methods for lifting liquid out of a wellbore employing such ball-shaped plunger. In certain embodiments, the ball plunger comprises a hole or a plurality of holes to aerate the fluid load.