SWAB Russian patent published in 2008 - IPC E21B43/00 E21B37/04 

FIELD: oil industry, particularly rigs for liquid lifting from wells via production strings by swabbing.

SUBSTANCE: swab comprises check valve, body with axial channel and annular beads and sealing members installed on the body between the beads. Swab also has elastic collar with protective bush and cavity between the collar and the body. The cavity is communicated with space over swab. Said cavity is additionally communicated with space over swab through axial channel of the body. Check valve is arranged in axial channel of the body below the collar. Check valve is made as rod and inverted cup having end provided with peripheral orifices and connected to rod from below. Inner cup surface has annular extension located below cup end. Safety valve is pressed to the annular extension with controllable force from below. Radial orifices are created in the cup below annular extension.

EFFECT: possibility of swab usage for liquid lifting along with pipe string wall cleaning of possible deposits, prevention of accidents, decreased metal consumption and labor inputs for swab removal from well.

2 cl, 1 dwg