Patent ID: 7140429

Claim:
An apparatus for cutting of slot-shaped key seats in a well by a hydro-sandblasting method, the apparatus comprising: a tube housing rigidly and hermetically joined with an end of a pumping compressing tube: an inner tube moveably and coaxially mounted inside the tube housing, the inner tube being spring-loaded from below with a cock spring; a top plug rigidly joined with the housing and moveable joined with the inner tube, and a bottom plug moveably joined with the housing and the inner tube; a hydro-abrasive perforator and a lower ball valve mounted at a lower end of the inner tube, the ball valve being disposed below the perforator; a hydro-brake comprising two vertical hermetic chambers disposed between the top plug and the bottom plug, the two chambers being divided by a piston with a self-adjusting channel for cross-flowing of a fluid between the two chambers, the piston being rigidly joined with the inner tube and moveably joined with the housing; the self-adjusting channel being formed between a matrix and a punch elastically pressed against each other and made as mutually coinciding recesses and protrusions, which are larger in size than the recesses.