HYDRAULIC CATCHER Russian patent published in 2006 - IPC E21B31/113 

FIELD: drilling equipment, possible use for freeing drilling column if it is stuck in the well.

SUBSTANCE: hydraulic catcher includes tubular body and hollow spindle, connected together without possible rotation. Upper and lower stopping collars are formed on spindle, between which a ring-shaped piston is mounted. Internal surface of body is made in form of cylindrical surface with a band of extended diameter for interaction with piston. Between body and spindle, seals of moving and immoveable connections are mounted, and also forcing and damping chambers are formed, filled with working liquid. Buffer hollow is formed in the body on the side of damping chamber. Piston ring is mounted in damping chamber with possible sliding, isolating damping chamber from buffer hollow. Between body and spindle, throttling channel is formed and a caging device is contained, and also a metering device, letting through a limited volume of working liquid during movement in throttling channel. Caging device is made in form of overflow bushing, positioned inside the piston, and packing bushing, positioned on the side of damping hollow. Metering device is made in form of at least one throttling groove on the end of piston between ends of piston and packing bushing in contact with each other. Packing bushing forms a circular running channel together with the body. Overflow bushing contains external circular collar in forcing chamber. Piston contains internal circular collar on the side of damping chamber. Overflow bushing in middle part is made with longitudinal slits. Drive of piston from the end of packing bushing, contacting the overflow bushing to external circular collar of overflow bushing exceeds distance from the end of overflow bushing, directed towards the damping chamber, up to close edge of each longitudinal slit.

EFFECT: increased efficiency when freeing pipes, increased reliability and resource.

4 cl, 6 dwg