WELLHEAD FACILITY FOR EXTRACTING PIPE STRING FROM BOREHOLE Russian patent published in 2010 - IPC E21B31/00 

FIELD: oil and gas production.

SUBSTANCE: invention refers to oil and gas production, particularly to wellhead facilities for extraction of emergency pipe string. The facility consists of a damper installed between a lifter generator of vertical pulses coupled with pipe string below. The damper corresponds to a vertical pressure tight cylinder with a piston, internal cavity of which is filled with gas. The generator is made as a tubular case consisting of successively coupled a power cylinder on top - with a rod of the damper piston and below - with a hollow chamber. The power cylinder is equipped with a power piston via a drain T-joint coupled with the pipe string by means of a hollow rod. An upper row of radial holes is located in a sub-piston cavity of the power cylinder, while middle and low rows of radial holes are located in a hollow chamber. Inside the holes are divided with a partition and they pass through the hollow chamber. The hollow chamber has an internal cylinder recess below. The sub-cavity of the power cylinder is equipped with the piston pump. A generator of hydraulic pulses corresponds to a hollow bushing pressure tight screwed into a lower part of the internal cylinder recess of the hollow chamber and put on the hollow rod overlapping the lower row of radial holes. The internal cylinder recess of the hollow chamber communicates with the middle row of radial holes and also communicates with the middle and low rows of holes when the hollow chamber with the hollow bushing travels downward relative to the hollow rod.

EFFECT: simplification of structure, reduced cost of fabrication and reduced metal input.

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