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

FIELD: oil and gas production.

SUBSTANCE: disclosed facility consists of lifter connected to damper and of generator of vertical pulses coupled with pipe string below. The damper corresponds to a cylinder with a piston, internal cavity of which is filled with gas under the piston. The generator of vertical pulses is made in form of a tubular case consisting of successively coupled power cylinders and of the damper connected above with a piston rod. The power cylinders are equipped with pistons successively connected by means of hollow rods so, that under piston cavities of the power cylinders are communicated between them and with the generator of hydraulic pulses via a distributor. The lower rod of the power piston is plugged from below and is connected to the pipe string. The distributor consists of the cylinder case with two chambers and is divided with a partition furnished with a one-stage valve for supply of liquid from a pump and with a back valve for discharge of liquid from the power cylinders. A safety valve is positioned between the distributor and a generator of hydraulic pulses; it is communicated with a buffer reservoir. All valves can operate with variations within wide pressure range.

EFFECT: facilitating selection of optimal mode of operation resulting in higher efficiency of stuck pipe string extracting from borehole, also facility is simple in design, not expensive in fabrication and low metal consuming.

1 dwg