WELLHEAD FACILITY FOR EXTRACTING PIPE STRING FROM BOREHOLE Russian patent published in 2010 - IPC E21B31/113 

FIELD: oil and gas production.

SUBSTANCE: disclosed here facility consists of lifter connected with damper made in form of pressure tight cylinder with piston, internal cavity of which is filled with gas, and of generator of vertical pulses made in form of tubular case. The case of the generator consists of a successively coupled power cylinder, on top connected with a piston rod of the damper, and of a hollow chamber positioned below. The power cylinder, under piston cavity of which is communicated with a pressure pump, is equipped with a piston connected with a pipe string via a discharge tee by means of a hollow rod. The hollow rod is equipped with a system of radial apertures, an upper row of which is arranged in the under piston cavity of the power cylinder, while a middle and lower rows are arranged with a bridge between them in the hollow chamber plugged from atop. The generator of hydraulic pulses is made in form of a hollow bushing with an internal cylinder groove pressure tight put on the hollow rod overlapping the lower row of radial apertures and communicating with the middle and lower rows of apertures simultaneously, when the hollow chamber travels downward relative to the hollow rod.

EFFECT: design of facility increases forces directed upward along axis of pipe string which raises efficiency of stuck pipe string extraction from borehole and also decreases metal consumption and cost of facility fabrication.

1 dwg