UNLATCHING JOINT Russian patent published in 2010 - IPC E21B17/06 

FIELD: oil and gas industry.

SUBSTANCE: unlatching joint includes upper and lower reducers connected to each other by means of fixture and vessel with corrosive fluid in relation to fixture. Bottom part of vessel is located above fixture and provided with a channel. Reducer is equipped with seat for waste valve, which is movable in axial direction, fixed in initial position against upward movement with the stopper, and against downward movements - with spring; at that, seat is provided with protrusion for covering the channel at bottom part of vessel. At that, seat body consists of two parts and provided with annular groove on outer surface forming together with upper reducer the cavity for arrangement of vessel with corrosive fluid. In case of sticking of tools from surface there released is valve which covers the seat passage channel. After that seat is lowered under pressure of washing fluid, protrusions of seat open the vessel channel and corrosive fluid enters the fixture zone and destroys it. After that pipe column is released from stuck part without application of torque moment and lifted.

EFFECT: device improves reliability and efficiency of works at elimination of accidents related to sticking of tools in well.

3 cl, 1 dwg